WEEDWATCH STANDING SENTINEL TO PROTECT PLANT HEALTH BROUGHT TO YOU BY

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1 WEEDWATCH

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3 WEEDWATCH CONTENTS American burnweed...34 Annual bluegrass...14 Annual lespedeza...7 Annual sowthistle...27 Barnyardgrass...24 Black medic...32, 62 Black mustard...59 Bristly oxtongue...47 Broadleaf plantain...9 Buckhorn plantain...22 Bull thistle...25 California burclover...45 Canada thistle... 8, 48 Carolina geranium...22 Carpetweed...17 Catchweed...50 Chamberbitter...52 Chicory...31 Common burdock...54 Common chickweed... 3, 15 Common cocklebur...57 Common dandelion...51 Common groundsel...13 Common lespedeza...19 Common purslane...21 Common sowthistle...9 Common vetch...48 Corn speedwell...16, 46 Creeping beggarweed...23 Creeping woodsorrel...13 Crowfootgrass Curly dock...12 Dallisgrass...26 Dandelion...6, 18, 31, 39, 51 Dogfennel...44 Dollarweed/pennywort... 5, 61 Downy brome...43 Eclipta...40 English lawn daisy...42 False dandelion...45, 51 Field sandbur...33 Goosegrass...11, 20 Goldenrod...59 Ground ivy...11, 23 Hairy bittercress...10, 49 Hairy leabane...49 Hairy galinsoga...40 Hairy nightshade...57 Hairy willowherb...58 Henbit...3, 26, 36 Horseweed...28, 44 Japanese stiltgrass...30 Kikuyugrass...19 Kyllinga...7 Large crabgrass...4, 16, 29 Large hop clover...18, 62 Lawn burweed...28 Lesser swinecress...41 London rocket...58 Matchweed...54 Mouse-ear chickweed...14 Narrowleaf hawksbeard...47 Orchardgrass...37 Parsley piert...15 Pearlwort...24 Pennsylvania smartweed...33 Pineappleweed...34 Prickly lettuce...27 Prostrate knotweed...21 Purple cudweed...50 Purple deadnettle...36 Red clover Red sorrel...61 Shepherd s purse...12 Slender aster...42 Smooth crabgrass... 5, 52 Smutgrass...55 Southern brass buttons...41 Southern crabgrass...43 Spurge... 8, 20 Stinkgrass...55 Threelower dwarf beggarweed..38 Tropical signalgrass...29 Virginia buttonweed...35 Virginia pepperweed...35 White clover... 4, 17 Wild carrot...32 Wild garlic Wild violet... 6, 46 Yellow foxtail...37 Yellow woodsorrel...10, 25 Weeds Postemergent Control Tips...56 Winter Preparation Tips LANDSCAPEMANAGEMENT.NET WEED WATCH

4 Dow Gallery Dow Gallery COMMON CHICKWEED Stellaria media HENBIT Lamium amplexicaule Low-spreading, prostrate winter annual or perennial has weak, shallow roots. Succulent plant grows in dense patches almost anywhere. Similar in growth habit and appearance to mousear chickweed (Cerastium glomeratum). Common chickweed leaves are less hairy and light green in color; mousear chickweed has dark green or gray-green leaves covered with soft hairs. For optimum control, apply as a pre-emergent in late summer/early fall. For post-emergent control, apply a two-, threeor four-way product that contains an active ingredient such as luroxypyr, triclopyr or clopyralid. Keep in mind that effectiveness is reduced as weeds mature. For optimum post-emergent control, apply to actively growing, immature weeds in the fall. If a spring application is made, you may need more than one application. Winter annual has square, lowering stems to nearly 10 in. tall. Commonly confused with purple deadnettle (Lamium purpureum). Deadnettle also has square stems, but its upper leaves have petioles (henbit does not) and its upper leaves are distinctly red- or purple-tinted. Henbit features mint-like pink to purple lowers. Prefers thin, nutrient-rich soil. Apply in late summer/early fall for pre-emergent control, before the weed germinates. For post-emergent control, apply a two-, three- or four-way product that contains one an active ingredient such as luroxypyr, triclopyr or clopyralid. For optimum postemergent control, applications should be made to actively growing, immature henbit in the fall. If a spring application is made to mature weeds, more than one application may be needed. For more information regarding these and other turf weeds, and related control technologies and tips, please visit or call 800/ PHOTOS COURTESY: RONALD CALHOUN (LEFT); SHAWN ASKEW JANUARY 2010 LANDSCAPEMANAGEMENT.NET 3

5 Dimension WHITE CLOVER Trifolium repens Gallery LARGE CRABGRASS Digitaria sanguinalis Low growing, creeping winter perennial with stems that root at nodes. Elliptical leaves in groups of three that usually have a light-green or white band like a watermark, plus some toothing on edges. White to pink-tinged lower clusters grow from long stems that usually rise above the leaves. Active growth from seeds or plants begins with cooler temperatures and increased moisture. Apply a in late winter or early fall before the white clover seeds germinate. Clean up any clover that may have survived the winter frosts with a spring application of a two-, three- or four-way post-emergent product that contains an active ingredient such as luroxypyr, triclopyr or clopyralid. Crabgrass is a bunchtype grass, light green in color, with seedhead spikelets in two to nine finger-like branches along the stalk. Summer annual germinates when soil temperatures reach a consistent 55 F. Tall, membranous ligule has jagged edges and no auricles. Leaves are rolled in the bud, and the collar is broad with long hairs. It grows under close mowing and prefers open areas with thin turfgrass. When soil temperatures reach 55 F in the spring, apply a pre-emergent grass. Choose the formulation that works best for your operation. There are several liquid, granular and fertilizer granule options. Consult the appropriate product label for recommended rates for your area, reseeding and overseeding recommendations. For more information regarding these and other turf weeds, and related control technologies and tips, please visit or call 800/ PHOTOS COURTESY: FRED YELVERTON (LEFT); SHAWN ASKEW 4 LANDSCAPEMANAGEMENT.NET FEBRUARY 2010

6 Dimension LockUp DOLLARWEED/PENNYWORT Hydrocotyle spp. SMOOTH CRABGRASS Digitaria ischaemum Green, glossy leaves, round in shape with scalloped edges. Long, slender petiole is attached to the center of the leaf, forming an umbrella-like appearance. Not to be confused with dichondra, in which the petiole is attached to the edge of a kidney-shaped leaf. Clusters of white lowers form in summer. Plants reproduce from rhizomes and seeds. Most often found in moist to wet sites or anywhere moisture is in excess. Minimize irrigation. Most turfgrasses can survive with less moisture than dollarweed can. Apply a post-emergent granule or liquid when dollarweed is actively growing. Dollarweed is a difficult weed to control for an entire growing season. Repeat spring or fall applications may be necessary. This summer annual germinates when soil temperatures reach a consistent 55 F. Offers prostrate growth habit, with leaves and sheaths that do not have hairs. Rolled vernation. It can be distinguished from Large crabgrass (Digitaria sanguinalis; see page 24 of the February 2010 issue) by the absence of hairs on the leaves and sheaths. Both species will grow under close mowing, but smooth crabgrass can survive and set seed at heights as low as 1/4 in. Seedhead features two to six finger-like spiked branches. When soil temperatures reach 55 F in the spring, apply a pre-emergent grass. Choose the formulation that works best for your operation. There are several liquid, granular and fertilizer granule options. Consult the appropriate product label for recommended rates for your area, as well as reseeding and overseeding recommendations. PHOTOS COURTESY: SHAWN ASKEW (LEFT); RONALD CALHOUN MARCH 2010 LANDSCAPEMANAGEMENT.NET 5

7 Turflon Ester Gallery WILD VIOLET Viola papilionacea DANDELION Taraxacum oficinale Small, pansy-like lowers feature five blue-violet, lilac or white petals. Heart-shaped leaves with scalloped edges are often cupped toward the petiole to form a funnel shape. It grows in bunches, reaching a height of 2 to 5 in. It s most often found in cool, shady, moist, fertile soil. Wild violet is difficult to control because of its aggressive growth and resistance to many s. Apply a post-emergence broadleaf as soon as violets reach the two-leaf stage of growth. The best control is provided by triclopyr, either alone or in two- and three-way combinations with other broadleaf s. Bright yellow blossoms of many petals are followed by puffball seed carriers. Long, hairless leaves with jagged teeth grow from low rosettes. Lealess, hollow stems emit a white, milky sap when broken. It grows all summer long in most conditions and soils, but thrives in thin turf. When soil temperatures are below 60º F in early fall or late winter, apply a broadleaf pre-emergence. It s good turf maintenance to reduce thin turf to help prevent spread. For more information regarding these and other turf weeds, and related control technologies and tips, please visit or call 800/ PHOTOS COURTESY: RONALD CALHOUN (LEFT); FRED YELVERTON 6 LANDSCAPEMANAGEMENT.NET APRIL 2010

8 Dimension LockUp ANNUAL LESPEDEZA Lespedeza striata KYLLINGA Cyperus brevifolius Summer annual features small, inconspicuous purple lowers and three slender oval leaves per node, with pronounced and pinnate veins. Hairs on stems point down. Grows all summer and blooms from August through October. Prostrate in structure, it thrives in areas where turf is thin. It grows so close to the ground that it is rarely cut with a mower. In early spring, apply a pre-emergent labeled for lespedeza control. Maintain a dense, actively growing turf through proper mowing, fertilizing and watering practices. If you use a postemergent, it is best to apply in late spring or early summer to allow the turfgrass a greater chance to fill in areas previously occupied by this weed. Dark-green, narrow, ridged leaves have a shiny, grass-like appearance. Tightly bunched round seed heads sit on spikes. Flowers bloom from May to October on three-sided triangular stems. This perennial plant forms dense mats, and thrives with low mowing preferring wet, poorly drained soils. Control soil moisture, because excessive moisture encourages growth and germination. Low, routine mowing heights reduce its persistence. Make multiple post-emergent applications of an arsonate like MSMA, or sulfonylurea- type s like halosulfuron or penoxsulam. PHOTOS COURTESY: NCSU TURF CENTERE S BRIDGET ROBINSON LASSITER (LEFT) AND FRED YELVERTON MAY 2010 LANDSCAPEMANAGEMENT.NET 7

9 Lontrel Snapshot CANADA THISTLE Cirsium arvense SPURGE Euphorbia maculata This creeping perennial s extensive rhizome system can extend up to 3 ft. It features smooth, oblong, irregularly lobed leaves with spiny margins. Pink or purple lowers bloom in late June through September, growing in 3/4-in.-diameter clusters. Unlike musk and bull thistles, the stems and lowers do not have spines or prickles. It colonizes in tall clusters (1 to 3 ft. in height), particularly in open areas. After the first lower buds are formed and before the first lowers open, apply foliar s, which move down through the plant and injure the root system. Repeat applications on regrowth may be needed. Removing shoots can stimulate growth on underground buds, which can generate new shoots a year or more after top-growth has been destroyed. Hand-pulling or mowing just spreads the growth of this problematic plant. Red- or purple-tinged stems host opposite leaves, and emit milky juice when broken. Oblong leaves are smooth or sparsely hairy, from reddish-green to dark green in color often with a maroon or purple spot in the center. The prostrate structure forms mats by branching from the base. This warm-season annual is found in disturbed soil, such as in gardens and lower beds, along sidewalks, and in open turf areas. Apply a broadleaf, pre-emergence in late spring. If you have germinated spurge, apply a post-emergent when the plants are small. Mulching of beds, adequate soil moisture and good fertility help control this species. Hand-pulling plants when they re small will minimize the seed deposits. PHOTOS COURTESY: SHAWN ASKEW 8 LANDSCAPEMANAGEMENT.NET JUNE 2010

10 Turflon Ester Ultra Lontrel COMMON SOWTHISTLE Sonchus oleraceus BROADLEAF PLANTAIN Plantago major This annual is hard to distinguish from perennial sowthistle (Sonchus arvensis) because both species are tall weeds with yellow, dandelion-like lowers and stems that produce a milky sap. Common sowthistle has a taproot and reproduces only by seed. Leaves are bluish-green alternate, clasping the stem with prominent, rounded spiny lobes. Bright yellow lowers bloom from June through August and turn into white puffballs similar to dandelions. Identify whether you have annual or perennial sowthistle. Herbicides registered for control of one form of sowthistle may not control the other. Check the label carefully. Clopyralid controls both annual and perennial sowthisthle. Tillage and low mowing help control annual sowthistle. This plant has a short, thick taproot that forms a rosette of leaves that lay lat to the ground. The broad, oval-shaped leaves have three to five prominent parallel veins, and are attached to the root system by a fibrous, celery-shaped petiole. Flowers appear on leafless, unbranched stalks that originate from the base of the plant. It adapts well to most sites including dry or wet conditions, heavy soils and very low mowing heights. This species typically requires repeat applications of triclopyr or twoor three-way mixtures of 2,4-D containing products. Helpful turf management practices include conducting soil aeration, avoiding overwatering, and using the proper mower cutting height for each turf species. Once under control, dense stands of turf and ornamentals will shade the soil surface making establishment of new plantain seedlings more difficult. PHOTOS COURTESY: DR. RUSS KLEINMAN, WESTERN NEW MEXICO UNIVERSITY DEPARTMENT OF NATURAL SCIENCES AND THE DALE A. ZIMMERMAN HERBARIUM (LEFT); DR.RONALD CALHOUN JULY 2010 LANDSCAPEMANAGEMENT.NET 9

11 Dimension HAIRY BITTERCRESS Cardamine hirsuta Snapshot YELLOW WOODSORREL Oxalis stricta The leaves on this winter or summer annual consist of two to four pairs of round lealets arranged alternately along the stem, up to 12 in. high. Individual lealets are round in outline. Small white lowers occur in clusters at the end of stems. It s often found in wet, disturbed areas such as landscape beds, containers or poorly drained turf. Hairy bittercress can have multiple genera-tions per year, and is spread by seed that projects when the plants are disturbed. Pre-emergent s are considered to be the best way to maintain control of this weed. When putting in landscape beds, start with weed-free soil. A few weeks after transplanting, apply a pre-emergent and cover with a layer of mulch. Be sure to read and follow the pre-emergent label to ensure all of your desirable plants are tolerant of the product. This perennial features hairy stems and reproduces via seeds and rhizomes. Leaves alternate along the stem with three heart-shaped lealets. Bright yellow lowers have five petals that lare outward. It prefers moist to slightly dry conditions in rich loamy soil. Yellow woodsorrel is not easily controlled with two-, three- or four-way post-emergence s. Repeat spring applications are usually needed. Ideally, a pre-emergence should be used to keep woodsorrel from becoming a problem. Check the product label to see whether woodsorrel is controlled. Perennial broadleaf weeds are capable of living more than two years. Proper turf maintenance is the key to controlling this weed. Fertilize, mow and water turf to encourage dense growth. PHOTOS COURTESY: DR. SHAWN ASKEW 10 LANDSCAPEMANAGEMENT.NET AUGUST 2010

12 Dimension * GROUND IVY Glechoma microcarpa Turflon Ester Ultra GOOSEGRASS Eleusine indica This prostrate creeping perennial has square stems several feet long that root at the nodes. Its rounded, scalloped leaves and small, funnel-shaped purple lowers grow in clusters. All plant parts feature a strong mint odor. It prefers moist, shady sites, and can tolerate low mowing heights. Fall is an excellent time to treat ground ivy; applications in spring (when it is in lower) are also a good time to get effective control. Research has shown that products containing triclopyr are effective in spring and fall, and more effective than 2, 4-D-based products during the diffi-cult summer period. Combinations of shade, wet soils and poor fertility favor ground ivy. Try and alleviate these conditions to maintain control. This prostrate-growing summer annual grows in a clump, with the base of the leaves being distinctively white to silver. Leaves are folded, and may be smooth or have a few hairs. It features a strong, extensive root system and readily invades hard, compacted soils found in high-traffic areas. Be sure your turfgrass is maintained properly so it grows vigorously and thickly. If you have had goosegrass previously, apply a pre-emergent labeled for goosegrass. Consider putting out two applications of pre-emergent each year in early and late spring. * The state of Arizona has not approved Turlon Ester Ultra for use on sod farms. ** State restrictions on the sale and use of Dimension apply. PHOTOS COURTESY: DOW AGROSCIENCES (LEFT); DR. RONALD CALHOUN SEPTEMBER 2010 LANDSCAPEMANAGEMENT.NET 11

13 Dimension CURLY DOCK Rumex crispus Confront SHEPHERD S PURSE Capsella bursa-pastoris This taproot perennial develops a rosette of wavy-margined leaves. It features a membranous sheath at the leaf base and usually swollen nodes. Flowers occur in greenish clusters at the top of the main stem, and become reddish-brown as they mature. Stems are unbranched, thick, without hairs, ridged and often reddish in color. It usually grows in wet areas, such as those caused by overwatering or standing water in low areas. It s best controlled post-emergence in the fall or spring, with two-, three- and four-way broadleaf s. Perennial weeds are capable of living more than two years, and thrive in weak, thin turf. Proper turf maintenance is the key to maintain control. Properly fertilize, mow and water to encourage dense growth. This winter annual forms a basal rosette and tall stems. It prefers disturbed soil on many growing sites. Leaves range from smooth to deeply lobed (more lobed as they mature). The lowering stalk produces lat, heart-shaped seed capsules and tiny white lowers. Because it spreads by seed, the plant dies quickly after producing its seedhead. Proper mowing will reduce seed production, as the seedhead is erect. It does not compete well with actively growing turf. Maintaining a healthy turf stand is the best control option. It will develop in areas that have been damaged over the summer and have not filled in during the fall. Apply a pre-emergent labeled for control of shepherd s purse prior to germination in fall or spring. * State restrictions on the sale and use of Confront and Dimension apply. PHOTOS COURTESY: DR SHAWN ASKEW; DR. RONALD CALHOUN 12 LANDSCAPEMANAGEMENT.NET OCTOBER 2010

14 Gallery Dimension COMMON GROUNDSEL Senecio vulgaris CREEPING WOODSORREL Oxalis corniculata This plant, which prefers cool, rich, moist soils, is a winter or summer annual. It can also be a biennial in coastal areas. It features a single stem or branched upright growth, 6 to 18 in. tall, and its yellow lowers bloom nearly year-round. Leaves are highly variable, from hairless to lightly covered with long wavy or cotton-like hairs. Groundsel reproduces by seed; each plant may produce three to four generations of seeds in one season. Because the seed is easily spread and can potentially deposit numerous seeds throughout the season, the best option for control is an earlyseason application of a pre-emergent broadleaf with at least three months residual, such as one containing the active ingredient isoxaben. To prevent common groundsel infestation, use good sanitation practices supplemented with preemergence broadleaf s. This summer perennial contains a slender, shallow taproot and roots at nodes along the creeping, slightly hairy stems. Leaves are deeply loped, heart-shaped and may be green to reddish-purple. Flowers are small and bright yellow, with five petals, and form in clusters of one to five at the end of slender stems. Mowing, fertilizing or irrigating turf is not an effective method of control * State restrictions on the sale and use of Dimension apply. this plant can actually be spread through such practices. If lawn mowers are used where creeping woodsorrel is growing, wash or air-spray mowers to remove seeds and clippings before moving to a weed-free turf. Once established, it is very competitive. Application of a pre-emergent labeled for Oxalis control in the fall is a good option. Two applications, four to six weeks apart, may be needed to get all the seedlings. PHOTOS COURTESY: DR. SHAWN ASKEW (LEFT); FOREST & KIM STARR, U.S. GEOLOGICAL SURVEY, BUGWOOD.ORG NOVEMBER 2010 LANDSCAPEMANAGEMENT.NET 13

15 Gallery Dimension MOUSE-EAR CHICKWEED Cerastium vulgatum ANNUAL BLUEGRASS Poa annua This spreading, matforming perennial prominently features hairy, prostrate stems. Its small white lowers have five notched petals that bloom in late spring. Leaves are noticeably hairy or fuzzy, long and narrow, and grow opposite; like the weed s common name, they resemble mouse ears. Commonly found in lawns, pastures and cultivated fields, mouseear chickweed spreads by seed, but can root at the nodes. Preventive practices can discourage infestation. Improve soil drainage and decrease shade if possible. Nitrogen fertility, liming and aeration will encourage a dense stand of turf, minimizing potential for mouse-ear chickweed establishment. Apply a pre-emergent broadleaf such as isoxaben prior to germination. This erect, or clumpforming, annual grass tolerates close mowing. It is light green in color, especially compared to the dark green of related turfgrasses. Leaves are keeled, and feature a distinctive boatshaped tip. Once soil temperatures fall below 70 Fahrenheit, germination of Poa annua will begin. * State restrictions on the sale and use of Dimension apply. Develop a dense, healthy turf to reduce sunlight at the soil surface. Keep soil phosphorous levels in the low-tomedium range. Cultural practices can reduce Poa annua, but s are needed for superior control. Poa annua produces most of its seedheads in the spring. Apply a pre-emergent grass, such as dithiopyr, prior to germination of seedlings. PHOTOS COURTESY: DR. FRED YELVERTON 14 LANDSCAPEMANAGEMENT.NET DECEMBER 2010

16 Dimension * Confront COMMON CHICKWEED Stellaria media PARSLEY PIERT Alchemilla microcarpa This low-spreading, prostrate winter annual succulent features oppositely arranged, small elliptic-shaped leaves, pointed at the tip and stems with rows of hairs. It grows in dense patches, and thrives in moist, shaded areas. It s similar in growth habit and appearance to mouse-ear chickweed (Cerastium vulgatum). Common chickweed leaves are less hairy and light green in color; mouse-ear chickweed has dark green or gray-green leaves covered with soft hairs. Apply a pre-emergent containing dithiopyr or isoxaben prior to germination in fall/winter. For post-emergent control, apply a two-, three- or four-way product that contains an ingredient such as triclopyr, luroxypyr or clopyralid. For optimum postemergent control, apply to actively growing, immature weeds in the fall/winter. If a spring application is made, you may need more than one application. This low-growing winter annual spreads by seed. Fan-shaped leaves alternate on the stems. The leaves contain three lobes, and each lobe is subdivided again into three to four lobes. The lowers are inconspicuous in the leaf axis. Apply a pre-emergent containing dithiopyr or simazine prior to germination in fall/ winter. This weed can be a major problem on nutrient-deficient lawns or lawns that are mown too closely. Manage with a good fertility program and keep mow height optimum for respective turfgrass. * Confront is not for sale or use in Nassau and Suffolk counties, New York. Other state restrictions on the sale and use of Confront apply. ** State restrictions on the sale and use of Dimension apply. PHOTOS COURTESY: DR. RONALD CALHOUN (LEFT); NORTH CAROLINA STATE UNIVERSITY TURFFILES JANUARY 2011 LANDSCAPEMANAGEMENT.NET 15

17 Dimension * Confront CORN SPEEDWELL Veronica arvensis LARGE CRABGRASS Digitaria sanguinalis This low-growing winter annual thrives in open turf, and becomes upright as it matures. Corn speedwell has small lower leaves that are rounded and toothed; the upper leaves are pointed. The plant, which is entirely covered in fine hairs, grows small bright blue lowers with white throats. A distinctive heartshaped seedpod grows below the lowers. It does not typically last long after lowering, and cannot live in high temperatures. Increase turfgrass density and minimize open turf areas by fertilizing, mowing and irrigating. Control winter annual broadleaf weeds before seed set. Treat early stages of growth with a product containing multiple broadleaf s, such as 2,4-D; MCPP; dicamba; clopyralid or triclopyr. Apply a pre-emergent broadleaf such as isoxaben in late summer. * Confront is not for sale or use in Nassau and Suffolk counties, New York. Other state restrictions on the sale and use of Confront apply. This light green, bunchtype grass features seedhead spikelets in two to nine finger-like branches along the stalk. The summer annual germinates when soil temperatures reach a consistent 55 F. Its tall, membranous ligule has jagged edges and no auricles. Leaves are rolled in the bud, and the collar is broad with long hairs. It grows under close mowing, and prefers open areas with thin turfgrass. When soil temperatures reach 55 F in the spring, apply a pre-emergent crabgrass. Choose the formulation that works best for your operation. There are several liquid, granular or fertilizer granule options. Consult the appropriate product label for recommended rates for your area, as well as reseeding and overseeding recommendations. ** State restrictions on the sale and use of Dimension apply. PHOTOS COURTESY: DR. FRED YELVERTON (LEFT); DR. SHAWN ASKEW 16 LANDSCAPEMANAGEMENT.NET FEBRUARY 2011

18 Snapshot WHITE CLOVER Trifolium repens LockUp CARPETWEED Mollugo verticillata This low-growing, creeping winter perennial has stems that root at nodes. Its tooth-edged elliptical leaves, in groups of three, usually have a light-green or white band like a watermark. White to pink-tinged lower clusters grow from long stems that usually rise above the leaves. Active growth from seeds or plants begins with cooler temperatures and increased moisture. Mechanical or physical removal is not recommended. Stolons may break, which increases the potential for more infestation. Apply a post-emergent granule labeled for white clover control, ideally prior to lowering in fall or late winter. Follow the label directions for appropriate timing and spread rates. This late-germinating, heavily branched summer annual forms circular patches several feet in diameter. Light-green leaves are smooth in whorls of three to eight at each node widest above the middle and tapering to the base. Stems are smooth and branched, lying on the ground with tips ascending. Small, white lowers cluster with slender, long stalks. Apply a pre-emergent prior to germination (before the soil temperatures reach 65 F) in the spring. Most pre-emergent s will control a broad range of species, so be sure to select a product labeled for carpetweed control. In a lawn setting, maintain a proper turfgrass mowing height. A base fertilizer program will encourage a lush lawn to compete with carpetweed. * State restrictions on the sale and use of LockUp and Snapshot apply. Consult the label before purchase or use for full details. PHOTOS COURTESY: DR. FRED YELVERTON (LEFT); DR. SHAWN ASKEW MARCH 2011 LANDSCAPEMANAGEMENT.NET 17

19 Lontrel Confront LARGE HOP CLOVER Trifolium campestre DANDELION Taraxacum oficinale This winter annual has trifoliate leaves similar to white clover (see March, page 46). Lealets have prominent veins, with the terminal lealet on a short stem. Short, hairy, slender stems are reddish in color and have a tendency to sprawl. Bright yellow lowers grow in clusters; each produces a single seed. Apply a post-emergent when clover is young and actively growing. All clover species are particularly susceptible to products containing clopyralid or luroxypyr. Good turf maintenance ensures a thick stand of grass and will help keep clover from recurring. Consider adjusting your fertility program to include more nitrogen and less phosphorous. This perennial weed thrives in weak, thin turf. Bright yellow blossoms have many petals, followed by puffball seed carriers. Long, hairless leaves have jagged teeth growing from a low rosette. Lealess, hollow stems emit a white milky sap when broken. A post-emergent application of two-, three- or four-way broadleaf s are most effective in spring or fall. Thick, healthy turf is important for managing this weed species. Properly mow, water and fertilize lawn to encourage healthy growth and minimize thin turf. * Confront is not for sale or use in Nassau and Suffolk counties, New York. State restrictions on the sale and use of Confront and Lontrel apply. Consult the label before purchase or use for full details. PHOTOS COURTESY: DR. SHAWN ASKEW (LEFT); DR. FRED YELVERTON 18 LANDSCAPEMANAGEMENT.NET APRIL 2011

20 Dimension KIKUYUGRASS Pennisetum clandestinum This aggressive perennial grass is adapted to warm, temperate climates. The prostrate plant spreads by producing a network of thick, leshy stems that can form a thick mat above the soil. Its leaves are folded in the bud. The ligule is a fringe of hairs, and there are no auricles. Growth begins in late spring, and a rapid growth rate continues through summer and into fall. Carbohydrates, stored in the stems, can be used for regrowth after cultivation. Turflon Ester Ultra Clean up the infested area with a product containing triclopyr. Multiple applications four to six weeks apart may be required. Clean mowing equipment to remove any seeds or stem sections before taking equipment from an infested site, as it is easily spread. Dense turfgrass and mulched ornamental areas block out sunlight and reduce the vigor of kikuyugrass. COMMON LESPEDEZA Lespedeza striata This prostrate, freebranched summer annual features inconspicuous purplish lowers. Leaves are trifoliate, with lance-shaped stipules and hairs along the leaf margins. Small single lowers grow from the leaf axils on most of the nodes on the main stems. Commonly found on soils with low fertility, it grows close to the ground in thin turf and dry, compacted areas. * State restrictions on the sale and use of Dimension products and Turlon Ester Ultra apply. Consult the label before purchase or use for full details. One of the best control options for this summer annual is to keep it from germinating. In spring, apply a pre-emergent labeled for control of common lespedeza. A product containing dithiopyr will control your grassy weeds, as well as lespedeza and many other broadleaf weeds. If turf is thin or compacted, alleviate compaction, raise your mowing height, and keep the soil s ph and fertility levels within appropriate guidelines for your turf. PHOTOS COURTESY: FOREST & KIM STARR, FOR THE HAWAIIAN ECOSYSTEMS AT RISK PROJECT, HEAR.ORG (LEFT); NCSU TURF CENTERE S BRIDGET ROBINSON LASSITER MAY 2011 LANDSCAPEMANAGEMENT.NET 19

21 Dimension GOOSEGRASS Eleusine indica SPURGE Euphorbia spp. (pictured: E. maculata) Dimension This annual emerges a few weeks after crabgrass, and continues well into the summer. The coarse, bunch-type grass features dark green leaves that form a basal rosette of prostrate to upright lattened stems. Compressed stems near the base are silver or white in color. Flowers contain two to 10 lattened, finger-like spikes that resemble a zipper. The strong, extensive root system invades hightraffic areas like athletic fields or golf courses. Improving turfgrass health and vigor through proper fertilization and maintenance is most advantageous. If possible, alleviate compaction and minimize traffic. For complete control, apply a pre-emergent such as dithiopyr just prior to crabgrass germination. This timing will provide season-long control of both crabgrass and goosegrass. Red- or purple-tinged stems and opposite leaves are common. All species emit milky sap when broken. Oblong leaves are smooth or sparsely hairy, reddish green to dark green in color often with a maroon or purple spot in the center. The prostrate structure forms mats by branching from the base. This warm-season annual is found in disturbed soil, such as gardens and lower beds, along sidewalks, and in open turf areas. Spurge plants are prolific seed producers. Apply a spring treatment of a pre-emergent that offers residual broadleaf weed control, such as dithiopyr. Spurge germination is prominent in compacted soils, so alleviating compaction, or the reasons behind compaction (such as poor drainage or nematode infestations) will help keep spurge infestations from occurring. * State restrictions on the sale and use of Dimension products apply. Consult the label before purchase or use for full details. PHOTOS COURTESY: DR. RONALD CALHOUN (LEFT); DR. SHAWN ASKEW 20 LANDSCAPEMANAGEMENT.NET JUNE 2011

22 GoalTender Gallery COMMON PURSLANE Portulaca oleracea PROSTRATE KNOTWEED Polygonum aviculare (Pictured: Polygonum aviculare ssp buxiforme) This prostrate summer annual grows rapidly in warm months, and tolerates poorly compacted soils and drought. Its distinct leshy, succulent foliage sets it apart from other weed species. Seedlings are oblong, succulent and hairless. Leaves are alternate, rounded at the apex and narrowed to the base. Young leaves are maroon on the lower surface. Small, yellow lowers bloom from May through September on hot, sunny days. Apply labeled for your use site, for preand post-emergence control. Oxyluorfen is most effective when applied as a post-emergent to seedling purslane, and will deliver residual control of emerging seeds. Once the area is free from purslane, use good management practices to prevent reinfestation. Clean cultivation and seeding equipment that may have been used in infested areas. Remove any purslane escapes before they set seed to minimize reinfestation. This prostrate summer annual is commonly found in pathways, sports fields and other compacted areas of turfgrass. Cotyledons are narrow, linear and often mistaken for grass. Stems below the cotyledons are often reddish in color. Leaves are arranged alternately along the stem. Short petioles and a distinctive, thin membranous sheath encircle the stem at the leaf base. Small, inconspicuous white to pinkish lowers grow in the area between the stems and leaves. As soon as temperatures warm up in the spring, apply a pre-emergence, such as isoxaben, labeled for knotweed control. Maintain a dense, healthy turf that will compete well with knotweed by the proper use of fertility, maintaining an appropriate mowing height for your turfgrass, uniform watering and compacted soil aerification. PHOTOS COURTESY: DR. RONALD CALHOUN (LEFT); STAN SHEBS JULY 2011 LANDSCAPEMANAGEMENT.NET 21

23 Confront Snapshot CAROLINA GERANIUM Geranium carolinianum BUCKHORN PLANTAIN Plantago lanceolata This winter annual or biennial is often called crane s bill because of the shape of the fruit. Leaves are deeply dissected and divided into five to nine toothed segments. As it matures, the basal rosette experiences stem elongation and branching. The densely hairy stems are erect, usually pink to red in color. Whitish-pink to purple lowers help differentiate this weed from smaller geranium species. Fall applications are recommended. Hand-pull any existing geraniums. Apply a pre-emergent broadleaf labeled for use on your ornamental beds. Products containing isoxaben are effective, and are labeled for ornamental plant tolerance on more than 630 ornamental species. This perennial turfgrass weed is commonly found in maintained turf, agricultural land and other disturbed sites. Leaves are footballshaped and spiral around a short stem, clustering around the base of the plant. It has narrower leaves and shorter lower stalks than broadleaf plantain (Plantago major). Flower heads consist of lealess, slender spikes of inconspicuous lowers clustered densely along the upright lowering head. Open lowers have protruding white stamens. In spring or fall, apply a post-emergent broadleaf with good translocation properties to thoroughly control the root system of this plant. Two- and three-way auxinic products provide thorough control. Properly fertilize, mow and water to maintain lush turf growth and minimize the potential for buckhorn plantain to establish itself. * Confront is not for sale or use in Nassau and Suffolk counties, New York. PHOTOS COURTESY: DR. SHAWN ASKEW (LEFT); DR. FRED YELVERTON 22 LANDSCAPEMANAGEMENT.NET AUGUST 2011

24 Confront GROUND IVY Glechoma hederacea Turflon Ester Ultra CREEPING BEGGARWEED Desmodium incanum This prostrate creeping perennial, featuring a strong mint odor, has square stems several feet long that root at the nodes. Rounded, scalloped leaves and small, funnelshaped purple lowers grow in clusters. It prefers moist, shady sites and can tolerate low mowing heights. Fall is an excellent time to treat ground ivy. Applications in spring, when the ground ivy is in lower, are also effective for control. Products containing triclopyr have proven to be highly effective in spring and fall, and more effective than 2,4-D-based products during the difficult summer period. Alleviate shade, wet soil and poor fertility to help maintain control. This perennial broadleaf weed, featuring pink lowers, is found across the Southeast United States. It develops from a large taproot and has many branched runners capable of rooting at nodes along the stems. Leaves are composed of three lealets elliptic in shape, pointed at the tip and rounded at the base. Both stems and leaves are hairy. Creeping beggarweed spreads by seeds, stolons or segments of the taproot. Creeping beggarweed can reproduce and spread in multiple ways. Two or more applications of a post-emergence may be needed. When beggarweed is young and actively growing, apply a two- or threeway product that will translocate through the foliage and root system. Keep proper mowing height, fertility and moisture to facilitate healthy, dense turf that can compete with beggarweed s aggressive nature. * Confront is not for sale or use in Nassau and Suffolk counties, New York. State restrictions on the sale and use of Confront and Turlon Ester Ultra apply. PHOTOS COURTESY: DOW AGROSCIENCES (FAR LEFT); FOREST & KIM STARR SEPTEMBER 2011 LANDSCAPEMANAGEMENT.NET 23

25 Snapshot BARNYARDGRASS Echinochloa crus-galli Team Pro PEARLWORT Sagina procumbens Ligules are absent in this summer annual. Rolled in the shoot, leaves have a distinct white mid-vein that becomes keeled toward the basal portions of the leaf. Its thick stems are tinted maroon at the base, and are often branched at the lower nodes. It may reach 5 ft. in height. Seedheads form terminal panicles comprised of individual spikelets. Apply a pre-emergent labeled for barnyardgrass control in mid to late spring for optimal control. One barnyardgrass plant can produce thousands of seeds, so preventing germination of the seed is critical. These seeds germinate and thrive in moist conditions in soils with high nutrient content. Cultural practices that will help reduce germination include proper fertilization and watering for the soil and turfgrass species present. Light, frequent irrigation increases the potential for barnyardgrass seed germination. This native, perennial broadleaf weed resembles moss, and typically inhabits disturbed sites or areas of moist, frequently irrigated turf. Prostrate to ascending stems root at nodes and form a mat. Leaves are narrow and hairless with pointed stems. They run opposite along the stem, but appear to be arranged in whorls. Seeds are spread by water splash and foot traffic. * State restrictions on the sale and use of Snapshot apply. Prevention and early eradication of this weed is important because of the prolific nature of the plant to set seed and the ease of which the seeds can be spread. Two- and three-way s that contain luroxypr will eradicate existing plants. Proper maintenance of turf will keep lawns healthy and diminish bare spots where pearlwort will thrive. A a pre-emergent containing isoxaben prevents germination. PHOTOS BY: RASBAK (FAR LEFT); MICHAEL BECKER 24 LANDSCAPEMANAGEMENT.NET OCTOBER 2011

26 Dimension Lontrel YELLOW WOODSORREL Oxalis stricta L. BULL THISTLE Cirsium vulgare This perennial weed is commonly found in greenhouses, ornamentals and turfgrass. Leaves are divided into three heart-shaped lealets with small yellow lowers. The presence of underground rhizomes helps distinguish yellow woodsorrel from creeping red woodsorrel (Oxalis corniculata), where the stolons are above ground. Five-petal lowers occur in clusters that grow from long stalks at the leaf axils. This weed is most effectively controlled by appropriately labeled pre-emergent s. In container and landscape settings, products containing dithiopyr or isoxaben provide excellent control. Yellow woodsorrel is not easily controlled by post-emergent s. Two-, three- or four-way mixes provide minimal postemergent control. This invasive, noxious biennial can form large infestations, especially along trails, roads and vacant fields. Plants grow erect, with spines on the leaves and stems. Arranged alternately on the lowering stem, leaves are lanceolate with deeply cut margins. They are coarsely hairy on the upper side, and contain softer, whitish hairs below. Rose to reddish-purple lowers grow at the ends * State restrictions on the sale and use of Dimension and Lontrel apply. of the branches, surrounded by spiny-tipped bracts. The invasive nature of this weed dictates early detection and control. It reproduces only by seed, so application prior to seed set is most effective. For optimum control, apply a post-emergent containing clopyralid in fall or early spring, when the thistle is in the seedling to rosette stage. PHOTOS BY: DR. SHAWN ASKEW (FAR LEFT); DR. RONALD CALHOUN NOVEMBER 2011 LANDSCAPEMANAGEMENT.NET 25

27 Dimension Gallery HENBIT Lamium amplexicaule DALLISGRASS Paspalum dilatatum This winter annual has square, lowering stems that grow up to 10 in. tall. Henbit features mint-like pink to purple lowers, and prefers thin, nutrient-rich soil. It is commonly confused with purple deadnettle (L. purpureum), but deadnettle s upper leaves have petioles (henbit does not) and are distinctly red- or purple-tinted. Apply a labeled, preemergent in late summer/early fall before the weed germinates. For post-emergence control, apply a labeled two-, three- or four-way product that contains luroxypyr, triclopyr, clopyralid or similar active ingredient. Post-emergence applications should be made to actively growing, immature henbit in fall. If a spring application is made to mature weeds, multiple applications may be needed. This abundantly seedproducing perennial grows in clumps with a tall, membranous ligule. Leaves are rolled in the bud and lack auricles. They also are without hairs except for several long, silky hairs that grow in the collar region. The seedhead is produced on a terminal stalk with three to five finger-like spikes branching from the center. Each spikelet is covered in black silky hairs. * State restrictions on the sale and use of Dimension apply. If present, the best way to eradicate dallisgrass is by digging out the clumps prior to formation of rhizomes or seed set. Dallisgrass seed begins to emerge when soil temperatures reach 60 F. For optimal control, apply dithiopyr in the spring just prior to these soil temperatures being reached. If dallisgrass is a problem in ornamental beds, apply a layer of mulch over the top of your pre-emergent. PHOTOS COURTESY: DR. SHAWN ASKEW 26 LANDSCAPEMANAGEMENT.NET DECEMBER 2011

28 Snapshot Gallery PRICKLY LETTUCE Lactuca serriola ANNUAL SOWTHISTLE Sonchus oleraceus This winter annual s leaves form in a basal rosette. It produces an upright step with alternating, deeply lobed leaves, which feature a row of spines along the mid-vein of the lower surface. Its deep tap root will secrete a milky sap. Small, yellow lowers appear in late spring to early summer. Prickly lettuce is a weed commonly found in container plantings and nurseries. For optimum weed control and plant safety on a broad range of ornamentals, apply a pre-emergent that contains isoxaben. Till the area prior to planting, or pull any existing seedlings prior to pre-emergent application. * State restrictions on the sale and use of Snapshot apply. This annual s bluish/ green leaves form a rosette, deeply lobed with prickly spines on the margin. Yellow lowers, similar to dandelion, appear in mid- to late summer but they form on a branched stalk vs. a hollow, solitary stem. Has a tap root, and all plant parts exude a milky sap when broken. It s often confused with prickly lettuce, but does not have spines along the mid-vein. For optimum control, apply a pre-emergent, such as isoxaben, that is labeled for control of annual sowthistle. Pre-emergence s must be applied before weeds germinate. Any existing annual sowthistle must be physically or chemically removed prior to pre-emergent application. Tilling of a landscape bed prior to planting and application will improve control of annual sowthistle. PHOTOS COURTESY: FREEBIGPICTURES.COM (FAR LEFT); FOREST & KIM STARR, STARR ENVIRONMENTAL, BUGWOOD.ORG JANUARY 2012 LANDSCAPEMANAGEMENT.NET 27

29 Snapshot LAWN BURWEED Soliva sessilis Gallery HORSEWEED Conyza canadensis This low-growing, freely branched, winter annual germinates when temperatures begin to cool. This weed reproduces by seed. In early spring, it begins to grow rapidly, forming spine-tipped burs in the leaf axis. It has opposite, sparsely hairy leaves, twice divided into narrow segments, or lobes. Small lowers bloom in the spring. Its burs are often hard to see, but easily felt. Maintain a healthy lawn by fertilizing and mowing at the proper height and frequency. Healthy grass can outcompete burweed for light, water and nutrients to reduce the level of infestation. Once this weed develops its burs, it is difficult to control and may need multiple applications of a post-emergent. Apply a labeled preemergence in the fall, before burweed germinates. Activate with 0.5 in. of rainfall or irrigation. Also known as marestail, this winter or summer annual can reach 6 ft. tall. Seedlings develop a basal rosette; young leaves are egg-shaped with toothed margins. Mature plants leaves are entirely without petioles. They are alternate with entirely or slightly toothed margins. White, pink or yellow inconspicuous lower heads occur at the top central stem of this prolific seed producer. * State restrictions on the sale and use of Snapshot apply. Glyphosate- and ALSresistant biotypes of this species have been confirmed in the United States, and are spreading across the country. As an annual weed that can produce more than 200,000 seeds per plant, pre-emergence s may provide the best option for control and will limit the spread of the resistant biotypes. Make a fall and early spring application of an appropriately labeled preemergent. PHOTOS COURTESY: DR. SHAWN ASKEW (FAR LEFT); DR. RONALD CALHOUN 28 LANDSCAPEMANAGEMENT.NET FEBRUARY 2012

30 Dimension Dimension LARGE CRABGRASS Digitaria sanguinalis TROPICAL SIGNALGRASS Urochloa subquadripara This light green, bunchtype grass features seedhead spikelets in two to nine finger-like branches along the stalk. The summer annual germinates when soil temperatures reach a consistent 55 F. Leaves are rolled in the bud, and the collar is broad with long hairs. Its tall, membranous ligule has jagged edges and no auricles. It grows under close mowing, and prefers open areas with thin turfgrass. When soil temperatures reach 55 F in the spring, apply a pre-emergence crabgrass. If you have missed the preemergent timing, you can apply an labeled for post-emergent control. Look for the active ingredient dithiopyr, which provides season-long preand early post-emergence control of crabgrass. There are several liquid, granular or fertilizer granule options. Consult the appropriate product label for recommended rates for your area, as well as for reseeding and overseeding. Commonly mistaken for bull paspalum or crabgrass, this blanketlike grass has relatively long spikelets, 3.5mm to 4mm. Crabgrass spikelets are narrower and not more than 3mm long. It roots from the nodes and has more papery leaves, compared with the soft leaves of crabgrass. The seedhead consists of modified racemes that emerge at right angles to the stem, spaced much like the signal lags used on ships. Once established in turf situations, this grassy weed is extremely difficult to control. Few, if any post-emergent s are effective in selectively removing this species in warm-season turf, where it is commonly found. Several pre-emergent s, such as dithiopyr, prodiamine, oryzalin, benefin + oryzalin or benefin + triluralin, have demonstrated good to excellent pre-emergent control of this species. * State restrictions on the sale and use of Dimension products apply. PHOTOS COURTESY: DR. SHAWN ASKEW (FAR LEFT); FLORIDAGRASSES.ORG MARCH 2012 LANDSCAPEMANAGEMENT.NET 29

31 Dimension Dimension CROWFOOTGRASS Dactyloctenium aegyptium JAPANESE STILTGRASS Microstegium vimineum This bunch-type summer annual is commonly found in sandy soils. Stems bend and root at the lower nodes, and have a spreading, creeping structure. Leaf blades and sheaths are without hair. Leaf margins have long, stiff hairs at the base. The lower head has two to seven spikelets at the tip of the stem. Its seed head resembles a crow s foot, and each plant may produce up to 60,000 seeds. Properly mow, water and fertilize lawn to encourage healthy growth and minimize thin turf. This species can be invasive and is a prolific seed producer. Appropriately labeled pre-emergent s are the most effective method of control. * State restrictions on the sale and use of Dimension products apply. This summer annual, also known as Mary s grass, resembles bamboo. Its leaves are pale green, lance-shaped and asymmetrical with a shiny mid-rib. Slender stalks of tiny lowers are produced in late summer, and dry fruits (achenes) are produced shortly afterward. It spreads by seeds and rooting at joints along the stem. Seeds produced by this plant can remain viable in the soil for at least three years. For non-selective control of established Mary s grass, glyphosate can be used. There are limited choices for complete post-emergent control of this species in established turfgrass. Mary s grass is identified as a class C noxious weed in some areas, so preventing the germination and establishment of it is critical. Apply a pre-emergent in early spring prior to germination. PHOTOS COURTESY: DR. SHAWN ASKEW (FAR LEFT); JAMES H. MILLER & TED BODNER, SOUTHERN WEED SCIENCE SOCIETY, BUGWOOD.ORG) 30 LANDSCAPEMANAGEMENT.NET APRIL 2012

32 Confront Turflon Ester Ultra CHICORY Cichorium intybus DANDELION Taraxacum oficinale This summer perennial develops from a basal rosette. While it looks similar to dandelion in the rosette form, its leaf lobes are not opposite. Bright blue to purple, square-toothed lowers form on stems that can grow up to 3 ft. tall. When cut, stems produce a milky liquid. Each plant can produce up to 3,000 seeds from June through September. It is most troublesome in disturbed areas and thrives in thinner turf, but it can be found in newly established turf. Properly mow, water and fertilize lawn to encourage healthy turfgrass growth, and inhibit the spread of chicory. When chicory is in the rosette stage, apply a systemic post-emergent, labeled for chicory control and your use site. This perennial grows all summer in moist conditions and soils, but thrives in weak, thin turf. Bright yellow blossoms have many petals, followed by puffball seed carriers. Long, hairless leaves have jagged teeth growing from a low rosette. Lealess, hollow stems emit a white milky sap when broken. A post-emergent application of two-, three- or four-way broadleaf s is most effective in spring or fall. Properly mow, water and fertilize lawn to encourage healthy turf growth and minimize thin turf. * Confront is not for sale or use in Nassau and Suffolk counties, New York. State restrictions on the sale and use of Confront and Turlon Ester Ultra apply. PHOTOS BY: L.L. BERRY, BUGWOOD.ORG (FAR LEFT); DR. FRED YELVERTON MAY 2012 LANDSCAPEMANAGEMENT.NET 31

33 Dimension Lontrel BLACK MEDIC Medicago lupulina WILD CARROT Daucus carota This low-trailing summer annual can act as a perennial in some conditions. It is common in lawns stressed from compaction, heat and drought. Often confused with clover, black medic is easily distinguished by the bright yellow lowers and leaf arrangement. The leaf is similar to clover and other legumes with three lealets, but black medic s center lealet is on a separate petiole. Prostrate stems, 1 to 2 in. in length, grow from a taproot. Clean up any established black medic using a post-emergent containing two or more auxinic s, such as clopyralid, triclopyr or luroxypyr. Time your application in spring or fall. Control starts with elimination of seed production, as each plant can produce thousands of seeds. Black medic germinates when soil temperatures are between 50 F and 75 F. Apply a pre-emergent prior to germination, or just after elimination via post-emergent control. This biennial resembles a garden carrot in its first year of growth. Also known as Queen Anne s lace, it produces a rosette of lobed, deeply dissected leaves in the first year of growth. Leaves have long petioles, hairless on the upper surface, but may have hairs on the veins and margins of the lower surface. The foliage has a carrot-like odor. During its second year, the plant starts producing stalks with umbels of numerous small white, lat-topped lowers. Apply a post-emergent when the wild carrot is in the seedling stage. Yearly applications are necessary to control the young seedlings that emerge from the seed bank. This weed species thrives in sandy and undisturbed areas. A well-maintained lawn with thick dense turf can outcompete the establishment of wild carrot. * State restrictions on the sale and use of Dimension and Lontrel apply. PHOTOS BY: DR. SHAWN ASKEW (FAR LEFT); L.L. BERRY, BUGWOOD.ORG 32 LANDSCAPEMANAGEMENT.NET JUNE 2012

34 Dimension Gallery FIELD SANDBUR Cenchrus incertus PENNSYLVANIA SMARTWEED Polygonum pensylvanicum This summer annual grass is commonly found in the Midwest and southeastern United States. Easily identified by the seedhead, which is a spike of tiny burs, it thrives in low-fertility, sandy soils. Sandbur forms in clumps because of a lack of rhizomes and stolons. Leaves are folded in the bud, and the ligule is a fringe of hairs. A pre-emergence program should be used where sandbur is a known problem. Many pre-emergence s used for crabgrass or goosegrass control also will control sandbur. Check the label. Sequential applications, 60 days apart, of a preemergence graminicide will ensure early- and late-germinating control of sandbur. Be sure to get your first application down prior to crabgrass germination. * State restrictions on the sale and use of Dimension products apply. As a member of the buckwheat family, this summer annual can grow up to 4 ft. tall, with multiple branching. Its stems are smooth and reddish purple with swollen nodes. The leaves alternate and are lance-shaped with a red watermark. Bristleless sheaths wrap around the stem at the base of the petioles. Small, bright pink lowers form dense, spike-like clusters on the stems from July through October. Its seeds are encased in glossy black achenes. Smartweed prefers disturbed areas, and tends to grow in moist soil. Ensure good drainage. Correct mowing height and fertility also can help prevent smartweed establishment. Apply a pre-emergence in early spring, prior to germination of summer annuals. PHOTOS COURTESY: DR. FRED YELVERTON (LEFT); DR. SHAWN ASKEW JULY 2012 LANDSCAPEMANAGEMENT.NET 33

35 Dimension Confront s* PINEAPPLEWEED Matricaria matricarioides Also known as wild chamomile, this summer or winter annual is commonly found in landscapes and turf, as well as compacted areas like walkways. Its finely dissected leaves emit a pineapplelike scent when crushed. This low-growing plant has a bushy appearance, with smooth, branched stems and alternating, hairless leaves. Greenish-yellow, coneshaped lowers grow at the ends of the stems on short lower stalks. Pineapple weed spreads by seed. Hoe or hand-pull any existing plants prior to bloom. This plant reproduces only by seeds that are released from the fruit at maturity. Apply a preemergent once the area has been cleared and soil has settled from rainfall or irrigation. In spring or late fall, apply a preemergent labeled for its control. * State restrictions on the sale and use of Dimension products and Confront apply. Confront is not for sale or use in Nassau and Suffolk counties, NY. AMERICAN BURNWEED Erechtites hieracifolia This rapid-growing, erect, summer annual is known for its alternate, sharp-pointed leaves with toothed margins. Common in cultivated areas, American burnweed tolerates moderate shade, but requires moist, well-drained soil. Small white or greenish lowers grow in open, terminal clusters. When plants mature, the lowers go to seed, resembling dandelion puffs. Seeds have parachutes attached that aid in wind dispersal and take root in a lawn s thatch layer. Its seeds have the ability to germinate in thatch, which makes the use of preemergent s somewhat problematic. Lowering your mowing height below the growing point of the plant is one method of control. Apply a postemergent, labeled for your use site. PHOTOS: BARBARA TOKARSKA-GUZIK, UNIVERSITY OF SILESIA, BUGWOOD.ORG (LEFT); JAMES H. MILLER & TED BODNER, SOUTHERN WEED SCIENCE SOCIETY, BUGWOOD.ORG 34 LANDSCAPEMANAGEMENT.NET AUGUST 2012

36 LockUp Confront VIRGINIA BUTTONWEED Diodia virginiana VIRGINIA PEPPERWEED Lepidium virginicum This spreading perennial grows along the ground. Stems root at the nodes and can be hairy. Its leaves are opposite and lance-shaped, and often have a yellow molting from the presence of a virus commonly associated with this weed. The seeds are thick and oblong, darker green on the upper surface and lighter green below. Star-shaped, white lowers grow between the leaf and the stem. Removing Virginia buttonweed by hand is often ineffective, because creeping roots or fragments left behind may re-establish. Apply two- or threeway products containing synthetic auxins such as luroxypyr, dicamba or clopyralid. Granular products containing penoxsulam are also labeled for Virginia buttonweed control. Multiple applications of granule or liquid products may be needed for complete control. This annual weed develops as a basal rosette, eventually producing lowering stems with a bottle-brush appearance. Its seedlings, which grow on long petioles, are hairless and ovalshaped. Rosette leaves are lobed along both sides of the leaf. Leaves that grow along the lowering stem are linear and without petioles. Stems are erect and branched, reaching heights of 20 in. Virginia pepperweed germinates in cool soil, and can invade fall plantings of cool-season turf that have not yet developed. Low mowing will prevent seedheads from developing, and minimize the development of new seed. Apply a postemergent to plants that are actively growing in the seedling to lower stage. Some products containing both triclopyr and clopyralid can be applied to cool- and warm-season turfgrass. * Confront is not for sale or use in New York s Nassau or Suffolk counties. State restrictions on the sale and use of Confront and LockUp apply. PHOTOS COURTESY: DR. SHAWN ASKEW SEPTEMBER 2012 LANDSCAPEMANAGEMENT.NET 35

37 Dimension Gallery PURPLE DEADNETTLE Lamium pupureum HENBIT Lamium amplexicaule With square stems and purple-red lowers, this winter annual closely resembles henbit (Lamium amplexicaule). Opposite leaves with pointed tips often have a purple tinge. Leaves grow on short or long petioles dependent on where the leaf is located on the plant unlike henbit, where leaves lack petioles. Purple-red lowers grow in clusters of three to six in the upper leaves. Deadnettle, a member of the mint family, reproduces by seed. Purple deadnettle germinates in the fall and lowers in the spring. It thrives in thin turf and moist, shady sites. Dense, lush turf is the best way to reduce spread and encroachment of winter annuals. Properly mow, fertilize and water in spring and summer to minimize thin turf areas. Apply a preemergent containing dithiopyr prior to germination in the fall. This member of the mint family, from the same genus as purple deadnettle, features a square stem. Commonly confused with deadnettle, henbit leaves are also opposite but circular to heart-shaped, without petioles for attachment but with clasping leaves on the petiole. Pink to purple lowers grow in whorls in the upper leaves without petioles. Primarily found in turfgrass and landscapes, henbit prefers thin, nutrient-rich soil. Henbit germinates in the fall, reproducing by seed and lowers in spring. Dense, lush turf is the best way to reduce spread and encroachment of winter annuals. Properly mow, fertilize and water in spring and summer to minimize thin turf areas. Apply a preemergent containing isoxaben prior to germination in the fall. PHOTOS: DR. SHAWN ASKEW 36 LANDSCAPEMANAGEMENT.NET OCTOBER 2012

38 Dimension * ORCHARDGRASS Dactylis glomerata Kerb YELLOW FOXTAIL Setaria glauca This grassy perennial weed grows in bunches. It develops early and grows quickly, reaching 10 in. in height. In its younger stages, there is a papery membrane where the leaf attaches to the main stem. Mature grass consists of a dense tuft of basal leaves that grows from low vegetative shoots, and slender culms with a few alternate leaves. Culms are light green and hairless; they later become straw colored. Orchardgrass grows best in the cool weather of spring and fall and can adapt to shady areas, as well as frequent mowing. For areas with extensive growth, apply an containing pronamide as a preemergent or early postemergent, depending on the time of year. When there are a few weedy patches, orchardgrass can be removed with a shovel. Be sure to cut down 3 in. to 4 in. into the soil to remove the stems. This clump-forming summer annual has a seedhead resembling a fox s tail. Its leaves are rolled in the bud. Leaf sheaths are hairless, but the leaf blades have long silky hairs on the upper surface near the leaf base. Stems are erect, often lattened and without hairs, with a reddish tint at the base. Its seedhead is a cylindrical bristly panicle, which turns yellow at maturity. Yellow foxtail grows in moist, fertile soil during the mid- to late growing season. Maintain turf density and health through proper cultural control. Avoid close mowing and summer fertilization. Apply a preemergent containing dithiopyr one to two weeks prior to germination in the late spring or summer. Consider a postemergent if the weeds are small and actively growing. * Kerb is a federally restricted-use pesticide. ** State restrictions on the sale and use of Dimension products apply. PHOTOS: DR. SHAWN ASKEW (FAR LEFT); BRUCE ACKLEY, THE OHIO STATE UNIVERSITY, BUGWOOD.ORG NOVEMBER 2012 LANDSCAPEMANAGEMENT.NET 37

39 Confront WILD GARLIC Allium vineale Accord XRT II THREEFLOWER DWARF BEGGARWEED Desmodium triflorum This perennial grows from bulblets that emit a strong garlic or onion smell when crushed. Its seedlings resemble those of a grass but have hollow, round leaves that grow from a bulb. The only stems that occur are lowering stems slender, solid, waxy and unbranched. Small, greenish-white lowers grow from the tops of the lowering stems. Smaller bulblets and fibrous roots may form at the base of the bulbs. Wild garlic is difficult to eradicate because several bulblets will sprout and grow at different times from the same plant. In actively growing turf areas, sequential applications of two- or three-way s containing 2,4- D applied in the winter and very early spring will provide control. Additional treatments the following year may be needed. In completely dormant bermudagrass or in noncrop areas, a glyphosate product can provide control when applied twice in the winter months. This perennial has leaves with three small, heart-shaped lealets. It propagates through seeds and stolons. The prostrate hairy stems root at nodes. It lowers in warm months. Flowers are blue or purplish pink. Its close relative, creeping beggarweed (Desmodium canuum), has leaves with three lealets that vary in size and are elliptic, pointed at the tip and rounded at base. Canuum also has hairy stems ascending to erect. Flow- ers are pink to rose color. It can propagate through seed, stolons or broken taproot. To minimize the establishment and spread of both Desmodium species, maintain a lush lawn with proper mow height, fertility and water management. Repeat applications either pre- or postbloom of a product containing triclopyr and clopyralid are recommended. PHOTOS: DR. FRED YELVERTON (FAR LEFT); FOREST & KIM STARR, STARRENVIRONMENTAL.COM 38 LANDSCAPEMANAGEMENT.NET DECEMBER 2012

40 Defendor Defendor COMMON DANDELION Taraxacum oficinale RED CLOVER Trifolium pratense This perennial overwinters as a small rosette of leaves. Seedlings grow from a taproot, and begin to emerge in early spring when soil temperatures reach 50 degrees F. Solitary, bright yellow blossoms grow on the end of lealess, hollow stalks that emit a white milky sap when broken. It produces a puffball seedhead shortly after mowing, and seeds are easily dispersed by wind. Dandelions prefer moist conditions and soils but thrive in weak, thin turf. For early-season control of weeds that overwintered, apply a labeled, postemergent to turf early in the spring when temperatures are still cool. Properly mow, water and fertilize lawns to encourage healthy growth and minimize thin turf. Florasulam can be applied when the first fertilizer and liquid preemergent applications of the season are made. This cool-season, perennial legume grows from a fibrous root system and is found across the U.S. Stiff, hairy stems root at the nodes, causing this weed to grow erect. Each leaf consists of three elliptical lealets, with a light green or white V-shaped watermark. Round pink to purple lower heads, made up of many small lowers, grow on lower stalks. * State restrictions on the sale and use of Defendor apply. As with any turfgrass weed, proper cultural maintenance of the lawn will greatly reduce the prevalence and presence of this weed. Properly mow, fertilize and water lawns to encourage healthy turf. When red clover is actively growing, apply a postemergent, systemic that will move from the treated foliage throughout the plant and into the extensive root system to completely control this weed roots and all. PHOTOS: JEFF HOWARD (FAR LEFT); SANJA565658, WIKIMEDIA COMMONS JANUARY 2013 LANDSCAPEMANAGEMENT.NET 39

41 Snapshot ECLIPTA Eclipta prostrata This prostrate annual, often called a false daisy, is typically found in the South, lower Midwest and along the East Coast. Stems below the cotyledons are light green to purple. Cotyledons are bald, slightly thickened and show a midvein on the lower surface. In mature plants, leaves are opposite, elliptic to lanceolate in shape and slightly thickened, with short, appressed hairs on both surfaces. Green to reddishbrown stems are freely Gallery branched and can root at the nodes. Small white lowers grow on small stalks at the end of stems or leaf axils. Early control is necessary to prevent rapid Eclipta growth. Apply a preemergent containing isoxaben, followed by 0.5 in. of irrigation. A sequential postemergent may be needed with dense populations. It s most effective when applied to plants less than 2 in. tall. HAIRY GALINSOGA Galinsoga ciliata This abundant seedproducing annual is found primarily in the Midwest and on the East and West Coasts. Young leaves are opposite and triangular, with slightly toothed margins. Hairy galinsoga is easily mistaken for eclipta as a young seedling, but the presence of hairs helps distinguish it. Stems reach 2 ft. in height; they are freely branched, green to maroon in color and covered in hairs. * State restrictions on the sale and use of Snapshot apply. Yellow inner lowers are surrounded by white to light pink outer lowers that grow from terminal stems. Hairy galinsoga can produce many viable seeds. It lacks seed dormancy, and shoots cut during cultivation can root rapidly even in semi-moist soils. Apply a preemergent containing isoxaben and triluralin to control hairy galinsoga in the landscape. PHOTOS: DR. CHARLES BRYSON, USDA AGRICULTURAL RESEARCH SERVICE, BUGWOOD.ORG (FAR LEFT); BRUCE ACKLEY, THE OHIO STATE UNIVERSITY, BUGWOOD.ORG 40 LANDSCAPEMANAGEMENT.NET FEBRUARY 2013

42 Gallery Turflon Ester Ultra SOUTHERN BRASS BUTTONS Cotula australis LESSER SWINECRESS Coronopus didymus This low-growing annual is often confused with swinecress, thanks to its similar leaves and flower heads. Swinecress has a skunk-like odor; brass buttons has no odor. Its seed leaves are long, narrow and fleshy, and the first true leaves are divided into three narrow lobes. Small, pale yellow flowers cluster into heads atop long stalks and bloom from January through May. In mature plants, finely dissected leaves are sparsely covered with short hairs. They re arranged alternately along the stem on short stalks. This member of the sunflower family is commonly found along the coast from California to Washington. Its broad leaves can take over a large area quickly, so it s important to treat this weed early. Apply a preemergent containing isoxaben prior to germination, followed by 0.5 in. of irrigation. This member of the mustard family is a lowgrowing, prostrate winter or summer annual that s often confused with southern brass buttons. First and later leaves alternate along the stems. The edges have one or more rounded, coarse teeth, and there are short hairs on the tips. Its leaves also have a skunk-like odor. Small white, fourpetaled flower clusters bloom from February through October. This quick-spreading weed is often found in lawns and gardens throughout the U.S. and is common in newly seeded fescue. Prolific seed production, tolerance to low mowing and heavy traffic have increased the prevalence of this weed in turfgrass. Apply a preemergent containing isoxaben early in the season or a postemergent containing triclopyr to emerged swinecress in late winter or early spring. * State restrictions on the sale and use of Turflon Ester Ultra apply. PHOTOS: FOREST & KIM STARR, STARR ENVIRONMENTAL, BUGWOOD.ORG MARCH 2013 LANDSCAPEMANAGEMENT.NET 41

43 Gallery Sapphire SLENDER ASTER Eurybia compacta ENGLISH LAWN DAISY Bellis perennis This herbaceous annual weed is commonly found in the southeastern U.S. along the coastal plains in dry, sandy soils. It s a small, erect plant with several stems and a thick, woody base. Left untreated, slender aster can grow 1 to 3 ft. tall. Thick, veined leaves alternate along the stems. Pale violet to reddishpurple ray lorets with pale yellow centers emerge from midsummer to early fall. This spring/summer weed grows in warmer temperatures and easily camoulages itself in lawns and fields, hiding under taller, more aggressive grasses. Its lowers produce tiny seeds, dispersed by wind and water throughout the grass, so it s essential to control this weed before it lowers and goes to seed. Apply a preemergent containing isoxaben or a combination product of isoxaben and triluralin in early spring, before soil temperatures are warm enough to initiate germination. This fibrous rooted perennial has a prostrate, spreading growth habit. Because it spreads through a rapidly advancing rhizome system, it has the potential to root and produce new plants at each node along individual rhizomes. Its basal leaves are nearly smooth, loosely hairy and margined or variably toothed. They are broad at the top and narrow at the base. Flower heads consist of tiny white or pink petals * State restrictions on the sale and use of Sapphire apply. surrounding a yellow center; the lower stalks generally exceed the leaves in length. In California, seedlings germinate from April through September. Postemergent applications of products containing penoxsulam should be applied in late summer to early fall. To optimize control of English lawn daisy, make two to three sequential applications 28 days apart. PHOTOS: CHOESS, WIKIMEDIA.ORG (FAR LEFT); DAVID MONNIAUX, WIKIMEDIA.ORG 42 LANDSCAPEMANAGEMENT.NET APRIL 2013

44 Dimension SOUTHERN CRABGRASS Digitaria ciliaris DOWNY BROME Bromus tectorum Kerb * This annual, warmseason grassy weed reproduces by seed and forms dense stands in open, disturbed or thincanopy sites. It grows along the ground with branched stems that root at the nodes. Leaf blades are rough with no hairs or only a few short hairs near the base of the blade. Long hairs are often on leaf margins near the sheath and on the sheath itself, similar to large crabgrass (D. sanguinalis). Southern crabgrass typically germinates when soil temperatures reach a consistent 55 degrees F. In the absence of frost, Southern crabgrass can overwinter producing new growth and a second crop of seed in spring or early summer. Apply an containing dithiopyr prior to germination or prior to the tillering of crabgrass, which generally corresponds to the time when crabgrass seedlings are easily observed in turf. * State restrictions on the sale and use of Dimension products apply. Downy brome, also known as cheatgrass, has densely hairy leaves and sheaths and drooping seedheads. Its leaves are rolled in the shoot and hairy on both surfaces. Leaves lack auricles and have a membranous ligule that may be fringed with hairs near the top. In late spring/early summer, the seedhead, a soft drooping panicle, changes from green to purple to tan. It often remains purple during the winter months. ** Kerb is a federally Restricted Use Pesticide. Flowers consist of individual spikelets with needlelike awns. Cutting is not a recommended control method for downy brome. If cut prior to seed ripening, it will produce new stems and seeds at the cut height. For smaller infestations in commercial settings, apply an containing pronamide. Make fall application(s) after downy brome seeds have germinated and are beginning to grow. PHOTOS: FOREST & KIM STARR, STARR ENVIRONMENTAL, BUGWOOD.ORG (LEFT); LESLIE J. MEHRHOFF, UNIVERSITY OF CONNECTICUT, BUGWOOD.ORG MAY 2013 LANDSCAPEMANAGEMENT.NET 43

45 Dimension HORSEWEED Conyza canadensis DOGFENNEL Eupatorium capillifolium Lontrel Also known as marestail, horseweed is sometimes mistaken for dogfennel. The immature rosette (pictured) looks much different than the mature plant. Seedlings develop a basal rosette and young leaves are egg-shaped with toothed margins. Mature leaves are hairy, slightly toothed and crowded along the stem. Full-grown plants have leaves without petioles, and they become smaller farther up the stem. A postemergent containing clopyralid alone or clopyralid plus triclopyr will clean up existing horseweed. This annual weed can produce more than 200,000 seeds per plant, so preemergent s may provide the best option for control. Apply a preemergent containing dithiopyr prior to germination in fall or early spring or in tank-mixtures with a postemergent containing clopyralid. This short-lived summer perennial is commonly found in the South and along the East Coast. Unlike horseweed, dogfennel s leaves are divided into thread-like segments, resembling a fern. Leaves will emit a foul odor if broken. The stems are reddish, hairy and grow from a woody base. Small, white lowers grow from branched panicles. Apply a postemergent containing clopyralid, which will translocate throughout the plant, controlling the dogfennel roots and all. For preemergent control of dogfennel, apply an containing isoxaben prior to germination or in a tank-mix with a postemergent labeled for dogfennel control. Dogfennel will not thrive in thick, established turf. Because of its upright growth habit, it will not tolerate low mowing. Properly mow, fertilize and water to encourage dense turf. Trademark of The Dow Chemical Co. ( Dow ) or an affiliated company of Dow. * State restrictions on the sale and use of Dimension products and Lontrel apply. PHOTOS: BRUCE ACKLEY, THE OHIO STATE UNIVERSITY, BUGWOOD.ORG (LEFT); 44 LANDSCAPEMANAGEMENT.NET JUNE 2013

46 Gallery Defendor * CALIFORNIA BURCLOVER Medicago polymorpha This annual low-growing weed is common in thin turf with low nitrogen levels. It contains three oblong, hairless lealets with miniscule teeth along the edges. The center lealet is on its own petiole. Its inlorescence is a cluster of yellow lowers, similar to small hop clover (Trifolium dubium). Burclover reproduces by seeds from burred seedpods, as well as spreading prostrate stolons, which allow the weed to tolerate close mowing. Mechanical removal is not recommended, as stolons may break and sprout, increasing the infestation. Clean up any existing burclover with a postemergent application of a product containing clopyralid or triclopyr. Apply a preemergent containing isoxaben in early fall or any time prior to germination, or immediately after cultivation. Also, consider adjusting your fertility program to include more nitrogen and less phosphorus. FALSE DANDELION Hypochoeris radicata Also known as hairy cat s ear, this perennial weed closely resembles common dandelion (Taraxacum officinale). Leaves are arranged in a basal rosette and are densely hairy with toothed or irregularly lobed margins. This is in contrast to common dandelion, which has highly divided, hairless leaves. Lealess lower stalks are present, with two to seven yellow ray lowers on each stalk. Leaves and lower stalks emit a milky sap when broken. As with any turfgrass weed, proper cultural maintenance of the lawn will greatly reduce false dandelion s prevalence and presence. Properly mow, fertilize and water the lawn to encourage healthy turf. When false dandelion is actively growing, apply a postemergent systemic such as lorasulam that will move from the treated foliage throughout the plant and into the extensive root system. Trademark of The Dow Chemical Co. ( Dow ) or an affiliated company of Dow. * State restrictions on the sale and use of Defendor apply. Always read and follow label directions. REBEKAH D. WALLACE, UNIVERSITY OF GEORGIA, BUGWOOD.ORG (LEFT); TOM HEUTTE, USDA FOREST SERVICE, BUGWOOD.ORG JULY 2013 LANDSCAPEMANAGEMENT.NET 45

47 Dimension * Turflon Ester Ultra * CORN SPEEDWELL Veronica arvensis WILD VIOLET Viola spp. This low-growing winter annual thrives in open turf and often appears in solid stands. It has small lower leaves that are rounded and toothed; the upper leaves are pointed. The plant, which is entirely covered in fine hairs, grows small bright blue lowers with white throats. A distinctive heartshaped seedpod grows below the lowers. Corn speedwell does not typically last long after lowering, and cannot live in high temperatures. Increase turfgrass density and minimize open turf areas with proper fertilization, mowing and irrigation. Because winter annuals germinate in the fall, treat this weed prior to germination in late summer or early fall with a preemergent containing dithiopyr. If speedwell is established, treat early stages of growth with a product containing clopyralid or triclopyr. This low-growing, clumping perennial can reach heights of up to 5 in. It grows from a dense, fibrous root system. Small, pansy-like lowers feature five blue-violet, lilac or white petals. Heart-shaped leaves with scalloped edges are often cupped toward the petiole to form a funnel shape. It s most often found in cool, shady, moist, fertile soil. Wild violet is difficult to control because of its aggressive growth, waxy leaves and resistance to many s. Apply a postemergent broadleaf as soon as violets reach the two-leaf growth stage. Repeat applications may be necessary if the violets are well established. In turfgrass and sites labeled for use, apply a postemergent containing triclopyr, either alone or in two- and three-way combinations with other broadleaf s. Trademark of The Dow Chemical Co. ( Dow ) or an affiliated company of Dow. *State restrictions on the sale and use of Dimension products and Turlon Ester Ultra apply. Consult the label before purchase or use for full details. Always read and follow label directions. PHOTOS: F. YELVERTON (LEFT); ROB ROUTLEDGE, SAULT COLLEGE, BUGWOOD.ORG 46 LANDSCAPEMANAGEMENT.NET AUGUST 2013

48 Gallery * Lontrel * NARROWLEAF HAWKSBEARD Crepis tectorum BRISTLY OXTONGUE Picris echioides This taprooted annual has a basal rosette and leaves similar to dandelion (Taraxacum officinale). Leaves are egg shaped, with the wider portion toward the tip. They are usually dissected or lobed. Basal leaves grow on petioles; stem leaves do not. Stems are erect, without hairs, and branch at the base. Up to 20 yellow lowers bloom in an open cluster at the top of the plant and on stems branching from the leaf axis near the top. This plant is very invasive, particularly in nutrientrich environments. Apply a postemergent containing clopyralid to actively growing weeds. Only weeds that have emerged at the time of application will be affected. Once hawksbeard is under control, mulch landscape beds and encourage strong, healthy turf through proper fertilization, irrigation and mowing. This erect winter or summer annual, or sometimes biennial, broadleaf weed is commonly found in the Northern U.S., as well as in California and Nevada. Its seed leaves are broadly stalked, oval and hairless. The first true leaves are egg shaped and covered with coarse, barbed and bristly hairs, which grow from blister-like swellings. Later leaves become increasingly larger. Until the lower stem develops, plants exist as basal rosettes. Yellow lowerheads resemble dandelion and grow from the top of the lowering stem. Petals have toothed tips. For optimum control, apply a preemergent containing isoxaben prior to germination. Any existing oxtongue must be physically or chemically removed prior to application. Landscape bed tilling and application prior to planting also will help prevent this weed. * Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow. State restrictions on the sale and use of Lontrel apply. Consult the label before purchase or use for full details. Always read and follow label directions. PHOTOS: MICHAEL SHEPHARD, USDA FOREST SERVICE, BUGWOOD.ORG (LEFT); STEMONITIS, WIKIMEDIA.ORG SEPTEMBER 2013 LANDSCAPEMANAGEMENT.NET 47

49 COMMON VETCH Vicia sativa Confront * CANADA THISTLE Cirsium arvense Lontrel * This winter annual vine has leaves that divide into many lealets (eight to 16 per stalk) and form large mats of vegetation. Each lealet is arranged alternately along the stem and grows on a petiole. Lealets are oblong to elliptic in shape and may grow hairs. Toothed stipules occur at the base of the leaf petiole. Older leaves develop tendrils that help in climbing. Stems climb on other vegetation or trail along the ground. Dense, vigorous turf is the best way to reduce the encroachment of winter annual weeds. Properly mow, fertilize and water to encourage dense growth. For postemergent control, apply a two-, three- or four-way containing triclopyr, clopyralid or luroxypyr in the fall or spring. Use the higher labeled rate when applications are made in late summer on mature plants and during periods of drought stress. Cotyledons are clubshaped, dull green and relatively thick. Young leaves are covered in short hairs and leaf margins are wavy with spines. Mature plants feature smooth, oblong, irregularly lobed leaves. Pink or purple lowers bloom in late June through September, growing in 0.75-in.-diameter clusters. Unlike bull thistle (C. vulgare) or musk thistle (Carduus nutans), the stems and lowers do not have spines or prickles. Fall typically is the best time to control Canada thistle. After the first lower buds form and before the first lowers open, apply a postemergent that contains clopyralid. Apply prior to seed set. Repeat applications on regrowth may be needed. Removing shoots can stimulate growth on underground buds, which can generate more shoots after top growth has been destroyed. Hand-pulling or mowing also spreads growth. * Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow. Confront is not for sale or use in Nassau and Suffolk counties, New York. State restrictions on the sale and use of Confront and Lontrel apply. Consult the label before purchase or use for full details. Always read and follow label directions. PHOTOS: ALVESGASPAR, WIKIMEDIA.ORG (LEFT); S. ASKEW 48 LANDSCAPEMANAGEMENT.NET OCTOBER 2013

50 Snapshot * Gallery HAIRY FLEABANE Conyza bonariensis or Erigeron bonariensis HAIRY BITTERCRESS Cardamine hirsuta This summer annual or biennial broadleaf weed is commonly mistaken for horseweed (C. canadensis or E. canadensis) in the seedling stage; however, hairy leabane leaves are narrower and more crinkled. Its seed leaves are gray-green, twice as long as they are wide and hairless with short stalks. A mature plant can reach up to 4 ft. It is wellbranched, with lanceshaped upper leaves and egg-shaped lower leaves. Because its seed is spread by wind and is common in nursery plants, a preemergent product with an extensive list of tolerant ornamental species is ideal. Make fall and early spring applications of a preemergent containing isoxaben to turfgrass or ornamental settings. For early postemergent control in cool- or warm-season turfgrass, a product containing lorasulam can be used. The leaves of this summer or winter annual consist of two to four pairs of round lealets arranged alternately along the stem. Each leaf grows from a distinctly hairy petiole. Upper leaves are hairy and smaller than the lower basal leaves. Small white lowers grow in clusters at the end of stems. Hairy bittercress is often found in wet, disturbed areas, such as landscape beds, containers or poorly drained turf. This weed can have multiple generations per year and spreads by seed that project when the plant is disturbed. Preemergent s are considered to be one of the best control methods for hairy bittercress. When applying to landscape beds, start with weed-free soil. Several weeks after transplanting, apply a preemergent containing isoxaben and cover with a layer of mulch. Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow. *State restrictions on the sale and use of Snapshot apply. Consult the label before purchase or use for full details. Always read and follow label directions. PHOTOS COURTESY: FOREST & KIM STARR, STARR ENVIRONMENTAL, BUGWOOD.ORG (LEFT); S. ASKEW NOVEMBER 2013 LANDSCAPEMANAGEMENT.NET 49

51 Lontrel Defendor PURPLE CUDWEED Gnaphalium purpureum CATCHWEED Galium aparine Purple cudweed is a lowgrowing winter or summer annual or sometimes biennial, as some plants will survive into the second year to achieve maturity. It overwinters as a basal rosette, but it usually grows from an upright stem in the spring. Seed leaves and first true leaves have white to light gray woolly hairs. Mature plants are sparsely branched and grow 8 in. to 20 in. tall. Flower heads are crowded, spiked and densely arranged on the stems or at the base of leaf stalks. Cudweed is a relatively easy weed to control. First, maintain a dense, actively growing turf through proper mowing, fertilization and irrigation. It s best to control purple cudweed in the spring or fall when actively growing. Two-, three- and four-way s containing clopyralid provide good postemergent control. Apply to the plant before seed stalk formation. Also known as rough bedstraw, this annual is commonly found in moist, shady areas. Seed leaves are oblong to egg-shaped with slightly notched tips. Mature leaves are whorled with six to eight leaves per whorl. Small, downward-curved prickles cover the stems and leaves. Small, four-parted white or greenish-white lowers grow on short branches originating in the leaf axils on the upper parts of the plant. Long-term cultural control requires removing existing plants before they lower and produce viable seed. Hand-weeding, followed by a layer of mulch, works well in landscape settings. To control in turfgrass or bare-ground areas, apply a postemergent containing lorasulam when catchweed is actively growing. Florasulam can be applied at the same time the first fertilizer and liquid preemergent applications of the season are made. Trademark of The Dow Chemical Company ( Dow ) or an affiliated company of Dow. *State restrictions on the sale and use of Defendor and Lontrel apply. Consult the label before purchase or use for full details. Always read and follow label directions. PHOTOS: S. ASKEW (LEFT); ROB ROUTLEDGE, SAULT COLLEGE, BUGWOOD.ORG 50 LANDSCAPEMANAGEMENT.NET DECEMBER 2013

52 Defendor * Defendor * COMMON DANDELION Taraxacum oficinale FALSE DANDELION Hypochaeris radicata this perennial overwinters as a small rosette of leaves. seedlings grow from a taproot and begin to emerge in early spring, when soil temperatures reach 50 F. solitary, bright yellow blossoms grow on the end of lealess, hollow stalks that emit a white milky sap when broken. it produces a puffball seedhead shortly after mowing, and seeds are easily dispersed by wind. Dandelions prefer moist conditions and soils, but thrive in weak, thin turf. For early-season control of weeds that overwintered, apply a postemergent containing lorasulam to turf early in the spring, when temperatures are cool and the dandelions have not yet bloomed. thick, healthy turf is important for managing this weed species. properly mow, water and fertilize lawns to encourage healthy growth and minimize thin turf. Also known as cat s ear/ catsear or latweed, this perennial weed closely resembles common dandelion (Taraxacum oficinale). Leaves are arranged in a basal rosette; they are densely hairy with toothed or irregularly lobed margins. this is in contrast to common dandelion, which has highly divided, hairless leaves. Each lealess stalk has two to seven bright yellow ray lowers. Leaves and lower stalks emit a milky substance when broken. As with any turfgrass weed, proper cultural maintenance of the lawn will greatly reduce false dandelion s prevalence and presence. properly mow, fertilize and water lawns to encourage healthy turf. when false dandelion is actively growing, apply a postemergent, systemic, such as lorasulam, that will move from the treated foliage throughout the plant and into the extensive root system to provide control. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. * State restrictions on the sale and use of Defendor apply. Consult the label before purchase or use for full details. Always read and follow label directions. photos: F. YELVERtoN (LEFt); tom heutte, usda FoREst service, BugwooD.oRg january 2014 LANDSCAPEMANAGEMENT.NET 51

53 Snapshot * Dimension * SMOOTH CRABGRASS Digitaria ischaemum CHAMBERBITTER Phyllanthus urinaria this summer annual germinates when soil temperatures reach a consistent 55 F. it features rolled vernation and a prostrate growth habit. it can be distinguished from large crabgrass (D. sanguinalis) by the absence of hairs on the leaves and sheaths. Both species will grow under close mowing, but smooth crabgrass can survive and set seed at mowing heights as low as 0.25 in. when soil temperatures approach 55 F in late winter or spring, apply a preemergent crabgrass. Look for products containing the active ingredient dithiopyr. it provides season-long preemergent and early postemergent crabgrass control. consult the appropriate product label for recommended rates for your area, as well as reseeding and overseeding recommendations. this summer annual is often found in ornamentals and landscape beds, but has recently become more problematic in turfgrass. it s also known as gripeweed, leaflower or little mimosa, among other names. As a member of the spurge family, chamberbitter reproduces by seed found in the fruit attached underneath the branch. it s a small, erect plant with grooved stems, thin leaves and smooth margins. it grows from a well-developed taproot. in turf, apply a preemergent containing isoxaben prior to germination. For landscape or container-grown ornamentals, use a product containing isoxaben and triluralin. Apply preemergent products labeled for chamberbitter irst in early spring and again two to three months later for season-long control. hand weed any plants that may have emerged prior to application. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. * State restrictions on the sale and use of Dimension products and Snapshot apply. Consult the label before purchase or use for full details. Always read and follow label directions. photos: R. calhoun (LEFt); REBEkAh D. wallace, university of georgia, BugwooD.oRg 52 LANDSCAPEMANAGEMENT.NET FEBRuARY 2014

54 WEEDS101 WEEDWATCH Defendor * Dimension * ANNUALS annual weeds germinate from seed, grow, mature and die in less than 12 months. Preemergent s containing isoxaben or dithiopyr are excellent control agents for winter and summer annual weeds. apply several weeks prior to germination. WINTER ANNUALS germinate in fall through early spring, when soil temperatures and moisture levels are favorable. mature and lower in the spring and early summer. Set seed and die at the onset of high summer temperatures. Broadleaf winter annuals include henbit, lawn burweed and speedwell. grassy winter annuals include annual bluegrass and downy brome. SUMMER ANNUALS germinate in spring through summer, as temperatures rise and soil moisture is adequate. mature, set seed and die in the fall. Broadleaf summer annuals include common lespedeza (pictured), black medic and spurge. grassy summer annuals include crabgrass, goosegrass and green foxtail. PERENNIALS/BIENNIALS Postemergent s containing lorasulam or clopyralid can provide excellent control of many perennial and biennial weeds. PERENNIALS Perennials, such as white clover (pictured), live for three or more years. most perennial weeds reproduce from seed and/ or vegetative structures, such as roots or tubers. Simple perennials spread by seed. however, if cut, pieces may produce new plants. dandelion, curly dock and plantain are simple perennials that can grow actively during cool and warm weather. BIENNIALS Biennials complete their life cycle within two years. Biennial plants bloom, set seed and die in their second year. the irst year of development is mainly to grow food stores in the roots. common biennial weeds include bull thistle, musk thistle and wild carrot. many biennials are sometimes listed as shortlived perennials because, under certain environmental conditions, they do not complete their life cycle in the second year. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. State restrictions on the sale and use of Dimension products and Defendor apply. Consult the label before purchase or use for full details. Always read and follow label directions. photos: james h. miller & ted BoDNER, southern weed science society, BugwooD.oRg (LEFt); Dow AgRosciENcEs BY ANITA ALEXANDER, DOW AGROSCIENCES FIELD SCIENTIST march 2014 LANDSCAPEMANAGEMENT.NET 53

55 Confront * LockUp * MATCHWEED Lippia nodilora COMMON BURDOCK Arctium minus this mat-forming perennial is commonly found south of the transition zone and along coastal areas. opposite leaves with small teeth at the outer tip grow on hairy branching stems. its stem is angular and rigid when rolled between the ingers. purple to white lowers emerge around the tip of a brown seed stalk, forming a match head appearance. matchweed spreads by seeds and stolons along prostrate stems. For optimum control, use a selective postemergent containing triclopyr and clopyralid when matchweed is in the four leaf to lower stage of growth. maintain a healthy lawn by fertilizing and mowing at the proper height and frequency. healthy grass can outcompete matchweed for light, water and nutrients to reduce the population. matchweed prefers low, moist areas. improve aeration to prevent infestations. Also known as wild rhubarb, this biennial weed reproduces by seed. seedlings emerge in early spring. the light-green, leshy leaves are oval and slightly notched at the tips. in the second year, plants emerge from the root and can grow as tall as 10 feet. Adult leaves are triangular and coarsely veined. the upper surface is green and covered with stiff, straight hairs. the lower surface is whitish and woolly. A branched lower stalk emerges from the center of the rosette. a corolla of rose-purple lowers covered in slender-hooked bracts form at the top of the stalks in late spring to mid-summer. postemergent s containing penoxsulam are most effective when applied in the irst year during the rosette stage. hand-pulling or digging can be an effective control method for small infestations if conducted prior to seed production. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. Confront is not for sale or use in Nassau and Suffolk counties, New York. Other state restrictions on the sale and use of Confront apply. Consult the label before purchase or use for full details. State restrictions on the sale and use of LockUp apply. Consult the labels of products containing LockUp before purchase or use for full details. Always read and follow label directions. PhOTOS: J.m.garg, Wikimedia (left); UniverSiTy Of illinois extension 54 LANDSCAPEMANAGEMENT.NET april 2014

56 Dimension * SMUTGRASS Sporobolus indicus STINKGRASS Eragrostis cilianensis Snapshot * this erect, bunch-type perennial grass commonly is found in warmseason turf and often is identiied by a black fungus growing on the seedheads. its collar is divided into two parts by the midvein, and its sheath is smooth and round. the seedhead is a narrow spikelike panicle. smutgrass spreads by small seeds dispersed in wind and rain and by the transfer of equipment and grass clippings. A preemergent containing dithiopyr will control smutgrass prior to germination of seedlings. Because this weed can be tough to eradicate, consider making two to three sequential applications of dithiopyr, with the irst application in spring and subsequent applications occurring six to eight weeks after the last application. conduct cultural control practices, including proper mowing, fertilization and watering. this grassy summer annual is best identiied by its distinctive odor and grayish-green panicle. seedlings develop into tufted plants relatively quickly. Leaves are rolled in the bud. the lower surfaces are smooth and glossy, while the top of the leaf is rough with hairs along the margins. Auricles are absent, and the ligule is a fringe of hairs. sheaths are round and slightly lattened. for landscape or container-grown ornamentals, apply a labeled product containing both isoxaben and triluralin. Apply labeled preemergent products in early spring and again two to three months later for season-long control. hand-weed any plants that may have emerged prior to application. stinkgrass is not a common problem in well-established turfgrass. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. *State restrictions on the sale and use of Dimension products and Snapshot apply. Consult the label before purchase or use for full details. Always read and follow label directions. PhOTOS: JOhn W. everest, auburn UniverSiTy, BUgWOOd.Org (left); STeve dewey, UTah STaTe UniverSiTy, BUgWOOd.Org may 2014 LANDSCAPEMANAGEMENT.NET 55

57 POSTEMERGENTCONTROLTIPS LockUp * NORTH Weed pictured: Curly dock Turlon Ester Ultra * SOUTH Weed pictured: Dollarweed Postemergent s are most effective in spring or fall (preferred). Use higher rates when hard-to-control species are prevalent, when applications are made in late summer or to mature weeds or during periods of drier weather. Spot treatments with products containing triclopyr ester are particularly effective during these times. Use amine-based formulations of 2,4-D when temperatures are high and volatility is a concern. Do not apply s when the turf is stressed. Extreme weather conditions may inhibit the product s performance. Depending on the level of infestation, multiple applications may be needed for complete control. Two applications two to four weeks apart are ideal. Avoid overwatering. Excessive moisture encourages weed growth and germination. Curly dock and sedges thrive in these conditions. Aerate in spring or fall. Most postemergent s are more effective when applied to weeds that are young and succulent. Early-winter applications target winter annuals. Spring or summer applications control weeds actively growing during these seasons. Fall is a good time for applications to perennial or biannual weeds. Do not apply s when the turf is stressed. Extreme weather conditions may inhibit the product s performance. Adjuvants improve coverage and help penetrate the waxy leaf surfaces of species like broadleaf plantain and dollarweed. Be cautious with these additions to ensure they do not increase the potential for turf damage. Irrigate only when necessary. Deep, infrequent irrigation is better for turfgrass than light, frequent irrigation. Aerate in late spring or early summer. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. State restrictions on the sale and use of LockUp and Turlon Ester Ultra apply. Consult the label before purchase or use for full details. Consult the labels of products containing LockUp before purchase or use for full details. Always read and follow label directions. PHOTOS: S. ASKEW BY JAMIE BREUNINGER, DOW AGROSCIENCES TEChNICAL LEADER 56 LANDSCAPEMANAGEMENT.NET JUNE 2014

58 Confront * Lontrel * COMMON COCKLEBUR Xanthium strumarium HAIRY NIGHTSHADE Solanum physalifolium Rusby This branched, summer annual often is found along roadsides in cultivated ields and in vacant lots. it s especially prevalent in Southern states. The irst pair of leaves is opposite; subsequent leaves alternate. leaf surfaces are rough with short, stiff hairs. in mature plants, its stems are brown to purple with dark spots. it grows distinctive prickly burs in late summer and fall. The burs are covered with hooked prickles, which help facilitate dispersal. Seeds germinate from early spring through summer. early-season control is important, because cocklebur grows rapidly. apply a postemergent containing triclopyr and clopyralid when the cocklebur is shorter than 8 in. Use higher rates when applications are made in late summer to mature weeds and during periods of drought stress. Seed leaves of this summer annual are narrow and egg-shaped. The irst true leaves have wavy edges and prominent veins. mature leaves are increasingly larger and dark green to purple. leaves have visible short hairs, especially along the underside of the main vein, distinguishing it from black nightshade (S. nigrum), which is covered in inconspicuous minute hairs. Two to eight star-shaped, white lowers grow in clusters, typically may through October. control hairy nightshade postemergent before it sets seed to minimize future infestations. Because hairy nightshade is an annual plant, use an integrated management program to prevent seed production and deplete the soil seed bank. apply a postemergent containing clopyralid when hairy nightshade is actively growing. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. Confront is not for sale or use in Nassau and Suffolk counties, New York. State restrictions on the sale and use of Confront and Lontrel apply. Consult the label before purchase or use for full details. Always read and follow label directions. PhOTOS: charles T. BrySOn, USda agricultural research Service, BUgWOOd.Org (left); dr. QUenTin groom, national BOTanic garden Of BelgiUm JUly 2014 LANDSCAPEMANAGEMENT.NET 57

59 Dimension * Dimension * LONDON ROCKET Sisymbrium irio HAIRY WILLOWHERB Epilobium hirsutum this member of the mustard family is a competitive winter annual, commonly found in gardens, turf and other disturbed sites. seedlings are oval, hairless and grow on stalks that are equal in length to the blade. shallow-toothed leaves grow away from the base of the plant and alternate along the stem. Young plants exist as rosettes until they develop lowering stems at maturity. Apply a preemergent containing dithiopyr prior to germination in the fall in turfgrass or landscape settings. London rocket does not compete well with actively growing turf. maintaining a healthy turf stand is the best control option. hand-weeding is a viable control method only if the population is small and isolated. this semiaquatic, perennial weed is commonly found in shady, coastal areas and nursery containers. Axillary buds, found at the base of the stem, produce stolons. the stolons produce adventitious roots, which pull the stolons into the ground and develop into rhizomes. Leaves are opposite, long and toothed. they are also sessile, often clasping at the base. Flower buds develop after 10 to 12 weeks of growth, and the entire plant is covered with rose-purple lowers by mid-summer. small infestations can be dug up, but make sure the rhizomes, and the root fragments are removed as well. it s best to never let this perennial get established. prior to germination, apply a preemergent containing dithiopyr. make sequential applications at three- to four-month intervals for extended control. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. State restrictions on the sale and use of Dimension products apply. Consult the label before purchase or use for full details. Always read and follow label directions. PhOTOS: ZOOfari, Wikimedia (left); frank vincentz, Wikimedia 58 LANDSCAPEMANAGEMENT.NET august 2014

60 Lontrel * GOLDENROD Solidago spp. BLACK MUSTARD Brassica nigra Gallery This genus consists of more than 65 species. most are herbaceous perennials found in open areas. goldenrod often grows in patches. in many cases, a colony of plants is a clone of a single plant. Stems are erect and slender, and can grow up to 8 ft. tall. long, narrow leaves alternate along the stem. most are identiied by golden inlorescences clustered on long stalks. goldenrod usually blooms in late summer or early fall. goldenrod is a very effective colonizer. Wind-blown seeds can widely disperse and quickly establish in bare soil or places where competition from other plants is light. after the irst lower buds form and before the irst lower opens, apply a systemic foliar, which moves down through the plant and injures the root system. Products containing clopyralid or triclopyr work well. also known as shortpod mustard, this winter annual grows profusely and produces allelopathic chemicals that prevent germination of native plants. Stems grow erect, with a slight covering of stiff hairs on the lower portion and a smooth top half. leaves do not clasp around the stem. lower leaves are lobed; upper leaves are toothed. flowers resemble other Brassica or Cruciferae species, having four bright yellow petals. To prevent black mustard, apply a preemergent containing isoxaben in late summer or early fall, prior to germination. a postemergent product containing triclopyr may be applied to small and actively growing plants. ensure good drainage, as black mustard prefers moist soil. Proper mowing height and fertility also can help prevent establishment in turfgrass. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. State restrictions on the sale and use of Lontrel apply. Consult the label before purchase or use for full details. Always read and follow label directions. PhOTOS: rob routledge, SaUlT college, BUgWOOd.Org (left); h. Zell, Wikimedia SePTemBer 2014 LANDSCAPEMANAGEMENT.NET 59

61 WINTERPREPARATIONTIPS Defendor * Gallery CHEMICAL CONTROL CULTURAL CONTROL now is the time to prep turfgrass for the dormant season, especially in the north, where soil temperatures have begun to drop. fall fertilizer applications provide longer-lasting beneits to a lawn than those done at other times of the year. for best results, make one application in early fall and another six to eight weeks later. There are fertilizers designed for speciic seasons, so make sure to use a fall fertilizer that encourages root growth. for troublesome winter annuals and perennials, such as dandelion (pictured, above), chickweed and clover, use a postemergent containing lorasulam. Preemergent applications are also effective in the fall, so winter annuals and perennials have less of a chance to develop or multiply in spring. control henbit (pictured, right), speedwell and lawn burweed with a preemergent containing isoxaben. application timings vary by geography. in the north, fall/winter applications can be done as early as labor day. in warmer climates, they can be applied as late as October. fall is a great time to aerate, reseed and dethatch before the dormant season. dense, lush turf is the best way to reduce the spread and encroachment of winter annuals. aerate turf to help minimize thatch, relieve soil compaction, improve drainage and encourage strong turfgrass roots. Proper aeration helps the root systems become better established for the coming winter. fall is the best time to establish cool-season grass because the soil temperature is cool and there is less weed competition. first, rake the area to help break up the soil. Then mix topsoil and seed in a bucket, spread the mixture over the bare spots, and push it into the ground. lower the mower s cutting height in the fall, when the grass begins to store food reserves. The lower height helps strengthen the plants roots and crowns with nutrients that would have been used by longer grass blades. fall also is a good time to dethatch the lawn, removing the layer of dead vegetation that prevents moisture and nutrients from reaching the roots. * Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. State restrictions on the sale and use of Defendor apply. Consult the label before purchase or use for full details. Always read and follow label directions. PhOTOS: dow agrosciences (left); S. askew BY DAN LOUGhNER, DOW AGROSCIENCES PRODUCT TEChNOLOGY SPECIALIST 60 LANDSCAPEMANAGEMENT.NET OCTOBER 2014

62 LockUp * DOLLARWEED/PENNYWORT Hydrocotyle spp. RED SORREL Rumex acetosella Gallery This warm-season perennial often is found in moist to wet sites or anywhere with excess moisture. its green, glossy leaves are round and scalloped, resembling a miniature lily pad. a long, slender petiole is attached to the center of the leaf, forming an umbrella-like appearance. dollarweed often is confused with dichondra, where the petiole is attached to the edge of a kidney-shaped leaf. avoid excess mois - ture by minimizing irrigation and improving drainage. most turfgrass species can survive with less moisture than dollarweed. apply a postemergent containing penoxsulam when dollarweed is actively growing and in the one-leaf-tolower stage. Dollarweed is a dificult weed to control for an entire growing season. Repeat spring or fall applications may be necessary. this summer perennial grows best in acidic soils, and can be used as an indicator of low soil ph. Leaves alternate and form a basal rosette. mature leaves are arrowhead-shaped, with two basal lobes attached to a petiole. Leaves growing along the stem are more elongated and usually lack the basal lobes. the leaves become thick and leshy over the summer months. the margins of the leaf are smooth. red sorrel grows in undisturbed, poorly drained soils. low nitrogen fertility also encourages the growth of this weed. keep ph and fertility soil levels within appropriate local guidelines. apply a preemergent containing isoxaben, in combination with a postemergent application containing clopyralid, when plants are in the rosette stage. make the same application again in late spring to maximize control. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. State restrictions on the sale and use of LockUp apply. Consult the labels of products containing LockUp before purchase or use for full details. Always read and follow label directions. PHOTOS: S. ASKEW (LEFT); FOREST AND KIM STARR, STARR ENVIRONMENTAL, BUGWOOD.ORG november 2014 LANDSCAPEMANAGEMENT.NET 61

63 Defendor Defendor LARGE HOP CLOVER Trifolium campestre BLACK MEDIC Medicago lupulina this low-growing winter annual has trifoliate leaves similar to white clover (T. repens). Lealets have prominent veins, with the terminal lealet on a short stem. short, hairy, slender stems are reddish in color and have a tendency to sprawl. Bright yellow lowers grow in clusters, each producing a single seed. Active growth begins with cooler temperatures and increased moisture. Apply a postemergent systemic that will move from the treated foliage throughout the plant and into the extensive root system to completely control this weed. consider adjusting your fertility program to include more nitrogen and less phosphorus. proper turf maintenance also will greatly reduce clover s prevalence. in addition to fertilization, proper mowing and watering will encourage healthy turf. this creeping summer annual is common in lawns stressed from compaction, heat and drought. often confused with clover (Trifolium spp.), black medic is distinguished by its bright yellow lowers and leaf arrangement. the leaf is similar to clover and other legumes with three lealets, but black medic s center lealet is on a separate petiole. prostrate stems, 1 in. to 2 in. long, grow from a taproot. clean up any established black medic with a postemergent containing lorasulam. time your application in spring or fall. Black medic germinates when soil temperatures are between 50 F and 75 F. Apply a preemergent containing dithiopyr prior to germination or just after elimination via postemergent control. Nitrogen fertility and aeration also can help encourage a dense turf stand, minimizing black medic establishment. Trademark of The Dow Chemical Company ( Dow ) or an afiliated company of Dow. State restrictions on the sale and use of Defendor apply. Consult the label before purchase or use for full details. Always read and follow label directions. PHOTOS: S. ASKEW 62 LANDSCAPEMANAGEMENT.NET DECEMBER 2014