TPM/IPM Weekly Report

Transcription

1 TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture May 15, 2015 In This Issue... - Lace bugs - Ambrosia beetles - European pine sawfly - Carpenter ants - Spittlebugs - White pines browning - Slugs and snails - Fall cankerworms - Aphids - Maple tip borer - Pine needle scale - Powdery mildew - Watering plants - Phlox plant bug - Winter damage - Fungicides on fruit trees Beneficial of the Week Weed of the Week Plant of the Week Phenology Degree Days Announcements IPMnet Integrated Pest Management for Commercial Horticulture extension.umd.edu/ipm If you work for a commercial horticultural business in the area, you can report insect, disease, weed or cultural plant problems found in the landscape or nursery to sklick@umd.edu Coordinator Weekly IPM Report: Stanton Gill, Extension Specialist, IPM for Nursery, Greenhouse and Managed Landscapes, sgill@umd.edu (office) or (cell) Regular Contributors: Pest and Beneficial Insect Information: Stanton Gill and Paula Shrewsbury (Extension Specialists) and Nancy Harding, Faculty Research Assistant Disease Information: Karen Rane (Plant Pathologist) and David Clement (Extension Specialist) Weed of the Week: Chuck Schuster (Extension Educator, Montgomery County) Cultural Information: Ginny Rosenkranz (Extension Educator, Wicomico/ Worcester/Somerset Counties) Fertility Management: Andrew Ristvey (Extension Specialist, Wye Research & Education Center) Design, Layout and Editing: Suzanne Klick (Technician, CMREC) Lace Bug Activity Colin Stewart, USDA- APHIS, reported second and a few third instar azalea plant bugs (Rhinocapsus vanduzeei) nymphs on azaleas in Washington, D.C. on May 10. Marie Rojas, IPM Scout, is finding lace bugs feeding on the leaves of Amelanchier Autumn Brilliance in Central Maryland. Jessica Frakes and John Ford, Thrive, Inc. found The underside of this serviceberry leaf has lace bug nymphs and black fecal spots lace bug nymphs on azalea and crape myrtle in Bethesda on May 12. Lace bugs are also active on pieris in Washington D.C. this week. These different lace bugs have multiple generations per year in Maryland. Eggs overwinter inserted in plant tissue. Monitoring: Look for yellow stippling of new growth. Look on the underside of foliage for nymphs, adults, and black fecal spots. Damage on new growth indicates eggs have hatched and the new generation has started to feed. Control: Get good coverage of horticultural oil on the underside of foliage to reduce populations. Many products are labeled for lace bugs.

2 Ambrosia Beetles By: Stanton Gill, UME It has been a slow start for ambrosia beetle activity, but now the number of electronic pictures I am receiving is starting to pick up. We put out a special alert in early May and within a days we had nursery owners and landscapers calling in with reports of activity on their trees. Hopefully, most of you have caught this pest early. After we put out the alert on Monday we received calls and s reporting damage on plants in garden centers, landscapes and nurseries. Yellowwood appears to be a favorite of ambrosia beetles. Redbud Alleghany is reported to be one of the preferred hosts. A nursery owner from New Jersey called to report activity in their nursery and said that dogwoods that had been treated with bifenthrin were still being attacked. It my be the ambrosia beetle activity was so high that it became a numbers game where some were being killed, but some were managing to get through the barriers. Ambrosia beetles continue to be active this week. We have received multiple reports of ambrosia beetles infesting apple trees, not only in an orchard (Harford County), but also in container trees sold at big box stores and at a garden center in Anne Arundel County and one in Charles County. At the big box stores, ambrosia beetles were also in Japanese maples, plums, dogwoods, and cherries. A garden center has reported that it has heard from customers that ambrosia beetles are infesting crape myrtles in the landscape. These infestations are most likely largely related to winter damage, especially after two severe winters in a row. The number of adult beetles dropped in our alcohol traps on Wednesday through Friday as the temperatures dipped. It is supposed to warm up on Saturday and Sunday and be warm and humid. This weather encourages flight activity of Xylosandrus ambrosia beetles. Be watchful for their boring activity this weekend. Control options include permethrin (e.g. Astro) in landscapes only or bifenthrin which is now available as OnyxPro (same as Onyx which is being replaced, but the new product has new nursery, golf, and sod farm site use language). OnyxPro is for both landscape and nursery use. European Pine Sawfly Todd Franklin, The Brickman Group, found these European pine sawfly larvae in huge numbers on a row of pines in NW D.C. on May 7. They had completely defoliated two shrubs and were working on the rest of the row. Monitoring: Larvae are gray green. Look for them on two and three needle pines. Control: There is only one generation per year and in most areas these sawflies are late instars at this point in time so it might not be worth applying any control measures. If larvae are still small, Conserve (spinosad) or Orthene (acephate) can be applied to foliage. Squishing works or remove growth with clustering larvae. Look for the gray green larvae of European pine sawfly on two and three needle pines; they blend in well Photo: Todd Franklin, The Brickman Group 2

3 Carpenter Ants By: Stanton Gill, UME A landscaper brought a bottle of large black ants to our office this week. The ants were all over a customer s kitchen counters. The customer was obviously upset and wanted action. The ants that they brought in were carpenter ants, Camponotus pennsylvanicus (DeGeer). In their natural habitat, carpenter ants aid in the decomposition of dead, decaying trees. They normally nest in logs, stumps, and hollow trees. In May and June, I commonly get calls about these ants invading people s home, usually in kitchens and bathrooms. The large, dark-colored workers often invade homes in search of food. The name carpenter ants implies to many that they are going to cause structural problems to their house, like termites. Not true. The carpenter ants do not have the protozoa in their gut that is found in termites that allow them to digest cellulose (wood). Carpentar ants nest in wet wood. If you have a leaking faucet under the kitchen sink and the wood remains wet for extended periods then possibly carpenter ants might nest in the wood. Repairing the leak and replacing the wood with dry wood is all that is generally necessary. Often they are not nesting in the house but are found out in the landscape nesting in a rotting tree stump or a cavity in a tree. These ants seldom tunnel into dry, sound wood, but they may excavate moist, rotting wood and other soft materials (such as foamed plastic insulation board) to make satellite nests. Rarely will the expansion of a nest into a building s wooden timbers cause structural damage. Spittlebugs Ginny Rosenkranz, UME, found spittlebug nymphs on pine last week. We have a few spittlebugs on herbaceous plants around the research center here in Ellicott City. Adults do not produce spittle and quickly jump and fly if disturbed. Occassionally, we have years where this insect is found in high numbers. However, most of the time, it is not an insect that warrants control measures. A close-up of a carpenter ant Photo: Mohammed El Damir, Pest Management, Bugwood.org Nymphs produce spittle as protection from predators and desiccation Photo:Ginny Rosenkranz, UME White Pines Browning David Clement and Steve Algeier, UME, have both noted that a lot of white pines growing near highways are showing a lot of needle scorching in May. This scorching is probably an after effect of the salts applied to the roadways. White pines are very sensitive to salt injury. There is not much you can do at this time of year. 3

4 Slugs and Snails By: Stanton Gill, UME The warm weather and cool nights that cause moisture to settle on plants is making perfect conditions for slugs and snails. They are chewing holes on several herbaceous annuals and perennials in the nursery and in the landscape in early May. In nurseries, sprays containing mesurol can be used. Bait containing mesurol or metaldehyde will also control slugs and snails. I received an interesting Facebook message from my brother-in-law who is stationed in South Korea as a colonel in the U.S. Army. He sent an article on a new facial treatment in which they use snail mucus to treat human facial skin. It is supposed to take out wrinkles and remoisten skin. He is visiting us this July so if you want to place your orders for snail mucus ointment let me know and I will see what I can do for you. Fall Cankerworms Aaron Cook, Maryland Forest Service, is getting phone calls from landowners in southern Washington County about the damage being done by cankerworms again this spring. He noted: They have grown quickly this spring, and areas along Elk Ridge, Red Hill, and South Mountain are being defoliated. This is the second spring that cankerworm has been an issue in our County. We suspect the population to remain high for another year or two. The warm, dry weather is likely going to negatively impact trees that are already stressed from previous defoliation, poor site class, and advanced age, as they attempt to regrow leaves. Cankerworms are doing a lot of damage to trees in Washington County again this year. Look for defolation on trees (photo above) and fecal droppings on plants low to the ground (left photo) Photos: Aaron Cook, Maryland Forest Service 4

5 Spirea and Other Aphids Steve Sullivan, The Brickman Group, is finding aphids on spirea this week. We also have spirea aphids on Spirea prunifolia here in Ellicott City. Ants are present and tend the aphids to get them to produce honeydew as a food for them. The ants then protect the aphids from predators. The aphids are tiny and green so they might be hard to see. If you see a lot of ants along the stem, look closely for the aphids. Paul Wolfe, Integrated Plant Care, is finding aphids on a variety of plants including birch in Rockville and Bethesda. The aphids are producing honeydew which is dropping onto surfaces below. Sooty mold can then grow on the honeydew. Control: Predators such as lady bird beetles and syrphid flies feed on these aphids. Monitor for ant and predator populations. Often, control is not necessary. If you do treat, choose a material with minimal impact on beneficials. Black Cherry Aphid: If you have customers with sweet cherries in their landscapes, check the tip growth for black cherry aphids. Activity is starting now. The honeydew they produce drops onto the fruit on which sooty mold can grow. Look for twisted and curled new tip growth. Control: Insecticidal soap can be used. Steve Sullivan, The Brickman Group, found and photographed a heavy infestation of aphids on spirea Ants protect the aphids; the aphids produce honeydew as food for the ants Maple Petiole Borer Marie Rojas, IPM Scout, is finding that maple petiole borer is active on Acer rubrum Red Sunset on May 15. The damage usually occurs in the spring on new tip growth on 1 to 2 year old maples. Control: Prune out damaged branches. Look for the damage from the maple petiole borer in the spring Photo: Marie Rojas, IPM Scout 5

6 Pine Needle Scale, Chionaspis pinifoliae (armored scale) By: Nancy Harding, UMD Monitoring pine needle scale on Pinus mugo in Bowie on May 11 found the start of the first generation of crawlers. The Degree Days in Bowie on May 11 were 310DD. If degree day accumulations in your area are close or above 310DD, you should closely monitor plants infested with pine needle scale. If crawlers are active and populations are high enough to warrant control, it is time to treat. Crawlers will settle and feed on the previous year s foliage. Settled crawlers are flattened and yellow (see photo). There are two generations of pine needle scale: the first generation eggs hatch when Cornus kousa first blooms at approximately 283DD (~mid-may) and can continue to Immature & mature females & newly-hatched, hatch over a 7-10 day period; the second generation summer brown crawlers of the next generation Photo: E. Bradford Walker, Vermont Department of produced eggs begin hatching at approximately 1648 DD Forests, Parks and Recreation, Bugwood.org (~late July) and may hatch over a period of two to three weeks. We will continue to monitor this scale and report on its second generation crawler activity. Control: Many lady beetles and parasitic wasps feed on this pest; therefore, careful monitoring of predators and parasitoids, as well as using pesticides with little effect on beneficials, can allow biological control to suppress the population. However if control is warranted, use a summer rate of horticultural oil or an insect growth regulator (IGR) such as Distance or Talus to target crawlers. Powdery Mildew Marie Rojas, IPM Scout, is reporting that powdery mildew is just getting going on the leaves of Cornus florida Cherokee Princess and Physocarpus Center Glow in central Maryland. Bright, sunny days and cool nights promote powdery mildew infection. Look for powdery mildew on dogwood foliage as well as other plants in the nursery and landscape Photo: Marie Rojas, IPM Scout Watering Landscape Plants There is a chance of rain in the forecast over the weekend and early next week. If we don t get much or any rain, be sure to keep watering new landscape plantings to ensure plant survival and reduce plant stress. 6

7 Phlox Plant Bug Jessica Frakes, Thrive, Inc., is finding nymphs of phlox plant bug on summer phlox. This first generation rarely does significant damage. The second generation later in summer can be a serious problem when plants are in bloom. Look for the yellow stippling and distorted foliage caused by this feeding. The feeding by this plant bug can stunt plant. Control: For control, you can use any systemics (e.g. acephate) work. The first generation of phlox plant bug nymphs are now active on phlox Photo: Jessica Frakes, Thrive, Inc. More on Winter Damage Jean Scott sent in photos of winter damage on Leyland cypress on the Eastern Shore. She noted how it shows an amazing contrast of the browning! Jean Scott photographed this winter damage on Leyland cypress on the Eastern Shore Fungicides Applied to Fruit Trees We have had several questions on when it is best to apply fungicides to fruit trees before a rain or right after. Cassandra Swett and Kari Peter, Extension Fruit Pathologists, wrote these comments: There have been several small rain events in the evenings with threats of larger rainstorms that have, up to this point, failed to manifest. With rain events comes the question: is it better to spray before or after it has rained? The conundrum: if you spray before, the plants are better protected but the product may wash off. If you spray after, the plants may get in infected before you can get in to spray, but you know that the product is there. The take home message from this article: it s harder to wash off chemicals that you might think. Although a lot gets washed off, what sticks around really sticks and still works. It takes 1-2 inches to wash off enough fungicide to see a reduction in disease control, according to Dr. Annemiek Shilder s studies at Michigan State. 7

8 Beneficial of the Week By: Paula Shrewsbury, UMD Leafcutter bees: Good guys or bad? Leafcutter bees are a common group of solitary bees in the family Megachilidae. Megachilid bees have their pollen-carrying structure, called a scopa, on the ventral or underside of their abdomens. Most other families of bees carry pollen in baskets on their hind legs. Megachilid bees nest in hollow stems of plants or galleries in wood left by wood boring insects. Some will chew galleries in wood that is soft and rotting on the inside. Megachilid bees divide their nests into cells with each cell being rationed with a pollen-nectar mix upon which an egg is laid. The major groups of megachilid bees are either mason bees that use soil to build their nest cells, or leafcutter bees that use leaves to build their nest cells. We discussed mason bees in the April 3 rd newsletter. Today I want to discuss leafcutter bees because adult leafcutter bees usually start activity around this time of year. Leafcutter bees line their nest cavity and separate it into cells with circular leaf sections that they cut from various plants. You have likely noticed vary discrete circular sections cut from the edges of rose and redbud foliage, in addition to other plants that they use to construct their nests. If you find a leafcutter nest it reminds you of a cigar. Leafcutter nests usually consist of several cells. Eggs hatch within the cell, feed on the pollen left by its mother throughout the season, and usually pupate late in the season and spend the winter in the nests as newly emerged adults. Adults emerge from nests in the spring. Leafcutter bees are important pollinators of wildflowers, fruits, vegetables, and other crops. Some of the most significant native species of leafcutter bees are Osmia spp. which are used commercially as pollinators for alfalfa and blueberries. Leafcutter bees really are good guys they provide a valuable ecosystem service by pollinating numerous native and non-native plants. Removal of leaf discs by leafcutter bees may affect the aesthetics of plants but they cause no plant health issues and should be tolerated. Conservation of pollinators of all types is critical to maintain pollinator diversity and abundance to meet food pollination demands and support natural ecosystems. The adult leafcutter bee is feeding on the floral resources of Echinacea. Note the heavy load of pollen in the scopa (pollen carrying structure on the abdomen of Megachilid bees) of this bee. Photo: M. Raupp, UMD Circular pieces of leaves were removed from this redbud by leafcutter bee adults. Photo: Kimberly Steinmann, California Dept. of Pesticide Regulation, Bugwood.org Other Predator Activity We are receiving various reports of lady bird beetles feeding on aphids. Assassin bugs have been hatching over the past few weeks. And, now is the time to be looking for hatching of praying mantids. We usually see them in this are in mid to late May. All are generalist predators feeding on different insects, including plant pests, in landscapes and nurseries. 8

9 Weed of the Week By: Chuck Schuster Common Groundsel, Senecio vulgaris L. The weed of the week for this week in May is common groundsel, Senecio vulgaris L. It is currently being found in turf and landscapes. It is a member of the Asteraceae family, which also includes sunflower, dandelion, and thistles, with other names that include birdseed, ragwort, and grimsel. This weed has numerous yellow disk flowers. It is a winter annual, though it may germinate in all seasons. It can be a prolific seed producer, with the ability to produce flowers at temperatures as low as 32 O F. It can produce as many as 1,700 seeds per plant. This weed will grow from 4 to 18 inches in height and has deeply lobed leaves with toothed margins. Upon close examination of the leaves they can be found to be smooth or hairy. Leaves are arranged along the stem in a spiral pattern and are deeply scalloped or lobed in the margin. Stems are smooth. Yellow flowers will appear at the end of stems in clusters and can be one half inch in diameter. The seed head (fruit) which appears is very similar in appearance to dandelion, with a white puff ball that is easily distributed by the wind. This weed thrives in moist landscapes and lawns, and is a prolific seed producer with seeds that do not require cross-pollination. This weed can be toxic, as it contains the alkaloid, senecionine. The first step in control of common groundsel is sanitation. Where possible, prevent germination. If plants do become established, prevent seed production. One plant can produce many seeds that have the ability to move with the air currents. Chemical control of common groundsel is achieved using many preemergent products that include Snapshot and Surflan in the landscape. This weed is developing resistance to some herbicides including simazine (Princep). Post emergent control can be obtained using glyphosate products. Control in turf settings can be achieved using many broadleaf post-emergent products. Views of common groundsel Photos: Chuck Schuster, UME Plant of the Week By: Ginny Rosenkranz There are a number of wonderful rhododendrons from which to choose, but the native cultivar Rhododendron catawbiense Nova Zembla is an outstanding choice. Catawba rhododendrons have deep green leathery textured foliage that covers a densely branched, broadly rounded shrub that grows 6-10 feet tall and feet wide. The leaves are arranged alternately on the gray brown stem but appear to be whorled at the end of a branch. Nova Zembla was bred with an extremely winter hardy parent and as a result is one of the most cold tolerant bright red rhododendrons and it is also one of the most tolerant of warm weather, thriving from USDA zones 4-8. The breeding was a part of the Iron Clad hybrids due to their resistance to many of the diseases to which rhododendrons are susceptible. 9

10 The beautiful foliage is not what makes Rhododendron Nova Zembla a favorite. It is the large 5-6 inch flower clusters or trusses that bloom a deep blue red. The flowers start out as dark red buds that open to a funnel-shaped flower with dark red purple petals; the top petal has dark landing markings for pollinators. The flowers attract butterflies, hummingbirds and bees, and persist on the plant for two or more weeks. Like all Rhododendron, Nova Zembla requires moist, well drained, acidic soils and afternoon shade. In the landscape it can be used successfully as a foundation plant, a specimen plant, as a mass border or as a key ingredient to a woodland garden. It is best to prune off the spent flowers to ensure a beautiful bloom the following year. Insect pests include aphids and lace bugs while Botryosphaeria canker, crown rot, dieback, rust, shoot blight and shoestring root rot are found to be diseases that attack Rhododendron. Buds and open flowers of Rhododendron Nova Zembla Photos: Ginny Rosenkranz, UME Degree Days (As of May 14) Baltimore, MD (BWI) Dulles Airport Frostburg, MD Martinsburg, WV National Arboretum Reagan National Salisbury St. Mary s City To check degree day (DD) accumulations in your local area go to: Note: degree days reported in this newsletter use a base temperature of 50 F, a start date of January 1st, and the date of monitoring as the end date. 10

11 Phenology PLANT PLANT STAGE (Bud with color, LOCATION First bloom, Full bloom, First leaf) Baptisia australis Purple Smoke Full bloom May 14 (Ellicott City) Chionanthus retusus Full bloom May 10 (D.C.) Iris ensata First bloom May 11 (Ellicott City) Iris pseudocorus First bloom May 11 (Ellicott City) Liriodendron tulipifera Full bloom May 10 (D.C.) Prunus serotina Full bloom May 11 (Salisbury) May 14 (Ellicott City) Robinia pseudoacacia First bloom Full bloom May 11 (Ellicott City) May 11 (Salisbury) Upcoming Conferences: MAA Pest Walk May 20, 2015 Location: Irvine Nature Center, Owings Mills, MD Eastern Shore Pest Walk June 3, 2015 Location: Salisbury, MD Contact: Ginny Rosenkranz, Procrastinator s Pesticide Recertification Conference June 5, 2015 Location: Montgomery County Extension Office Contact: Chuck Schuster, A brochure is on-line Eastern Shore Pest Management Recertification Conference June 12, 2015 Location: Wye Research and Education Center, Queenstown, MD Contact: Ginny Rosenrkanz, Elkton, MD Meeting includes a 60th MCTA Anniversary celebration. For more inforamtion: GaverTreeFarm@aol.com or Alternative Greenhouse Crops Conference August 5, 2015 Location: Brookside Gardens, Wheaton, MD LCA Hands-on Training Seminar September 16, 2015 Location: Johns Hopkins Univesity, Mongomery County Campus MNLGA Nursery Field Day June 17, 2015 Location: Clear Ridge Nursery, Union Bridge, MD Greenhouse Tour and MNLGA Picnic June 25, 2015 Location: Greenstreet Growers, Lothian, MD Summer Meeting of the Maryland Christmas Tree Association June 27, 2015 Location: Pine Valley Christmas Trees, 342 Blake Road, 11

12 Come Out and Look at the Active Insects and Diseases on May 20th By: Stanton Gill, UME David Clement, Karen Rane, Mary Kay Malinoski and I will be working with the Maryland Arborist Association conducting an evening IPM Pest ID session in Baltimore County. There will also be presentations on handling pesticide spills by professional arborists with Davey Tree Expert Company and dealing with vines in trees by David Driver of Arbor-X. See the Maryland Arborist Association site for registration information. IPMnet is now on Facebook at CONTRIBUTORS: Stanton Gill Extension Specialist sgill@umd.edu (cell) Paula Shrewsbury Extension Specialist pshrewsb@umd.edu Karen Rane Plant Pathologist rane@umd.edu Chuck Schuster Extension Educator cfs@umd.edu David Clement Plant Pathologist clement@umd.edu Andrew Ristvey Extension Specialist aristvey@umd.edu Ginny Rosenkranz Extension Educator rosnkrnz@umd.edu Nancy Harding Faculty Research Assistant Thank you to the Maryland Arborist Association, the Landscape Contractors Association of MD, D.C. and VA, the Maryland Nursery and Landscape Association, Professional Grounds Management Society, and FALCAN for your financial support in making these weekly reports possible. Photos are by Suzanne Klick or Stanton Gill unless stated otherwise. The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by University of Maryland Extension is implied. University of Maryland Extension programs are open to all citizens without regard to race, color, gender, disability, religion, age, sexual orientation, marital or parental status, or national origin.