TPM/IPM Weekly Report

Transcription

1 TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture June 10, 2016 In This Issue... - Eastern tent caterpillars - Ambrosia beetles - Fletcher scale - Cottony camellia/taxus scale - Japanese maple scale - Lilac borer - Bagworm activity - Emerald ash borer - Aphids on river birch - Insect control on hollies - White pine weevil - Azalea leaf gall 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. Please include location. 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) Eastern Tent Caterpillars on Skip Laurel By: Stanton Gill Here is interesting insect damage that showed up this year. When we held the IPM Pest Walk at Hood College two weeks ago, we saw a skip laurel with caterpillars feeding on the foliage. On close examination, we found that eastern tent caterpillars had migrated and the late instar stages were feeding on the foliage of the laurel. Last Friday, I received an from Connie Bowers, Garden Makeover Company, with caterpillar damage on skip laurel in Silver Spring. Eastern tent caterpillars are usually found feeding on crabapples and cherry trees. When they reach the 4th and 5th instar stage, they often migrate off the original host plants and become general feeders. This change occurs just before pupation. At this point, the caterpillars have Late instar eastern tent caterpillars migrate off the original host and become general feeders; this tent is on skip laurel Photo: Connie Bowers, Garden Makeover Company spun their cocoons and are pupating. They will emerge as adults in early July. The females will lay egg masses on host trees in early to mid- July.

2 Ambrosia Beetle Update By: Stanton Gill Normally, I would say we were past the flight activity time of the Xylosandrus species of ambrosia beetles, but the wet, cool spring appears to have extended their flight activity time. We are receiving samples from alcohol traps in central and western Maryland that contain Xylosandrus germanus and X. crassiusculus. On Wednesday, I received an from an Eastern Shore grower who had three paw paw trees with fresh frass tubes coming out of the trunk. The grower is sending in the adults to our lab for identification this week. Brian Haga, Scientific Plant Service, found a heavy infestion in Phoenix last week at a residence. Meanwhile, if you have susceptible trees, I would suggest monitoring closely. It might be wise to make another application of either bifenthrin or permethrin to the the trunks of susceptible species such as styrax, dogwoods, yellowwood, and redbuds. Frass tubes show the continued activity of Xylosandrus species of ambrosia beetles Photo: Brian Haga, Scientific Plant Service Xylosandrus species of ambrosia are also a problem on paw paws Photo: Grower submission Maryland Department of Agriculture: Pesticide Container Recycling Program MDA has posted its schedule of collection sites for the 2016 Pesticide Container Recycling Program. Triplerinsed (or equivalent) will be colleted on the scheduled days and times at the sites. See the brochure for details. 2

3 Fletcher Scale (Parthenolecanium fletcheri) By: Nancy Harding Fletcher scale crawlers (egg hatch) were found June 10 in College Park on bald cypress (Taxodium distichum. This native soft scale prefers arborvitae (Thuja spp.) and yew (Taxus spp.). However, it has also been reported to attack juniper and cypress. Fully grown adult females are hemispherical in shape to slightly elongate (3/16 long) and can range in color from yellowish brown to tan to dark reddish brown. Fletcher scale can easily be confused with European fruit lecanium scale (Parthenolecanium corni); however, the host plant may aid with identification as this scale is largely found on deciduous trees while Fletcher scale infests conifers. First instars (crawlers) are smaller, flatter, yellowish in color and often feed on needles. One generation is produced each growing season in Maryland. Crawlers are active on Fletcher scale in College Park Photo: Nancy Harding, UMD Monitoring: The Degree Days in College Park as of June 9 were 852 DD. If the Degree Days in your area are similar to College Park s look for crawlers on terminal twigs and needles. In heavy infestations, large amount of honeydew and sooty mold will be produced. Control: Use Talus or Distance mixed with.05% horticultural oil when crawlers are present and if infestation warrants control. Cottony Camellia/Taxus Scale Jessica Frakes, Thrive, Inc., found crawlers of cottony camellia/taxus scale on Foster holles in D.C. on June 10. Chris Ward, John B Ward & Co., found crawlers on Sarcococca (sweetbox) in Gladwyne, PA on June 7. Monitoring: Look for yellowing of foliage and plant dieback in severe infestations. This soft scale produces large amounts of honeydew on which sooty mold will grow. The scale tends to accumulate on the undersides of foliage. There is one generation a year. Control: When you find crawlers, treat with pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5-1% horticultural oil. The fluffy egg masses are now producing crawlers of cottony camellia/taxus scale Photo: Chris Ward, John B Ward Co. Look for yellow crawlers by the fluffy egg masses Photo: Jessica Frakes, Thrive, Inc. 3

4 Japanese Maple Scale We received a report on June 9 that Japanese maple scale has just started to produce crawlers in central Maryland. Crawlers of this scale are active over a long period of time and often overalp with the next generation. Use a hand lens to look for the light purple crawlers. Double-sided tape can be wrapped around trunks of trees and then checked regularly to determine when crawlers are active. Control: Applications of 0.5-1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) should be made when crawlers are detected. This treatment should have about 2-3 week residual activity. At that time monitor your plants again to see if crawlers are still active. The twice-stabbed lady bird beetle provides some biological control of this scale. Japanese maple scale are small, but being purple helps make them easier to spot Lilac Borer Bob Mead, Mead Tree, sent a photo of a lilac borer pupa remaining on the trunk of an ash tree on June 6. Lilac borers also infest all ash and Syringa species including S. reticulata, S. villosa and S. chinensis. With the cool and wet weather, there has been a longer emergence time this spring. You might still find a pupal case of lilac borer on ash and lilacs; the emergence period is longer than usual this spring Photo: Bob Mead, Mead Tree Bagworm Activity Ron Rubin, Thrive Inc., is finding bagworms feeding on arborvitae in the City of Fairfax in VA. Marie Rojas, IPM Scout, is finding bagworm emergence in Laytonsville, Beallsville, and Gaithersburg. Contine to monitor your customers sites this week for bagworms on susceptible plants such as arborvitae, spruce, and Leyland cypress. Bagworms also infest deciduous trees, but the damage is usually less evident. Control: Check to make sure eggs have hatched before making any treatments. Bt (Dipel, Caterpillar Attack), Spinosad (Conserve) or Acelepyrn will all give good control of young larvae. Monitor susceptible trees closely for the small bagworms Photo: Ron Rubin, Thrive, Inc. 4

5 Emerald Ash Borer Adult emerald ash borer adults are still active. Craig Greco, Yardbirds, Inc., found emerald ash borer adults in ash in Hamilton, VA (western Loudon County) last week. Kolby Corrigan, Davey Tree, found adults emerging from their holes today in NW D.C. Kolby noted that the tree is heavily damaged and will be removed. These emerald ash borer adults were found under a treated ash tree Photo: Craig Greco, Yardbirds, Inc. Caught in the act - this emerald ash borer is emerging from the ash tree Photo: Kolby Corrigan, Davey Tree Aphids on River Birch Jim Harris, Wood Acres Tree Specialists, found aphid damage on weeping river birch on May 26 in Potomac. If aphid populations are high enough to warrant treatment, consider horticultural oil or Endeavor which have minimal impact on beneficials. With the sunny warm weather this week, syrphid fly activity has increased significantly. The larvae feed on aphids as well as other small insects. Lady bird beetles are also common predators of this aphid. Monitor birches regularly for spiny witchhazel gall aphids Photos: Jim Harris, Wood Acres Tree Specialists 5

6 Tight Hollies = Poor Insect Control By: Stanton Gill The continuous rain periods for the last 10 weeks have resulted in excellent growth on American and Chinese hollies. The new growth on American hollies is 8-10 in length this season in several nurseries. Many nursery managers are busy in mid-june having their field workers shearing the holly plants. A puzzling and bizarre practice is being used by some nursery managers who have decided that American and Chinese hollies have to be sheared as a tight growth plant. Often, they are shaped in rectangles, triangles, and other highly ridged shapes. When I was visiting nurseries in Germany and Holland, I saw similar heavy handed shearing being used repeatedly. These growers seemed to have forgotten what the natural beautiful form of holly are all about. These sheared plants look like cookie-cutter plants that were manufactured rather than grown. Some managers have told me this shaping is what landscape architects have put in their plans and it looks good at transplant time. American and Chinese hollies have a natural, beautiful spreading form that tends to be more open and graceful rather than an artificial sheared appearance. Aesthetics aside, this servere shearing is creating a problem when it comes to insect control. A tightly sheared growth pattern sets up control measures for failure of some of the major scales that infest holly plants. The biggest scale problems we have seen crop up on hollies over the last decade include cottony camellia/taxus scale, white prunicola scale and Japanese maple scale. The problem is that when plants are sheared into tight forms, it becomes extremely difficult to penetrate the canopy with most sprayers to make contact with the scale with an insecticide. You can hit the scale on the outer perimeter of the holly but fail when it comes to penetrating the interior. I am not suggesting giving up on shearing, but try doing it so the plant is a little more open in the canopy. If you develop a scale insect population, you can use Talus or Distance or horticultural oil. White Pine Weevil Marie Rojas, IPM Scout, found white pine weevil larvae in the terminals of Douglas firs at a Christmas Tree Farm in central Maryland. White pine weevils commonly infest pines and spruces. Larvae pupate in late July within the infested terminal. Adults emerge in late July and August and overwinter in leaf litter. There is one generation per year. Control: At this time of year, prune out flagging terminals. Next year, monitor for adult activity in March and April. To prevent damage the insect growth regular called Dimilin can be applied to terminal growth when the adult activity is noted among your conifers. Check flagging terminals of pine, spruce and Douglas fir for white pine weevil larvae Photos: Marie Rojas, IPM Scout Azalea Leaf Gall We are receiving reports of azalea leaf galls. Jim McWilliams found it on a property in Reisterstown. Stan Quillen, Waynesboro Garden Center, received a sample of it this week as well. Karen Rane discussed this gall in the May 20, 2016 IPM Report. 6

7 Beneficial of the Week By: Rebeccah and Paula Shrewsbury While identifying the insects trapped on yellow sticky cards used in my conservation strip experiment (see 29-April issue for more details), I had to carefully examine every small piece of what looked like detritus just in case it was an insect. Some of the tiniest insects on my yellow sticky cards were much smaller than even the most smallest of herbivores, thrips! I am referring to fairyflies or fairy wasps (Order: Hymenoptera). I was always pleasantly surprised when I encountered these tiny insects. However, these insects are not true flies. They are tiny parasitic wasps that are also called mymarids (Family: Mymaridae). In North America, there are about 145 species of mymarids, and body sizes of most of these are between mm long. A very large mymarid is considered to be 2.5 mm! Unlike closely related parasitic wasps, mymarids do not have a metallic sheen and are all matte yellow, brown, or black. Important diagnostic characters (viewable with a high magnification hand lens) include relatively long antennae that are at least as long as the head and half of the thorax combined. Many other similar-looking parasitic wasps have antennae that are no longer than the head. Secondly, the hindwings of mymarids are stalked, unlike most other insects with wings that are broadly attached to the body. Usually, a fringe of long setae (hairs) surrounds the wing tips, giving them a feathery appearance. All mymarids are egg parasitoids of other insects, and especially of eggs that are concealed or inserted in plant tissue or soil. Some scientists know the specific host egg from which a mymarid species emerge (known as a host record). The most common hosts (45%) of mymarids based upon verified host records are the eggs of cicadas, leafhoppers, planthoppers, treehoppers, and froghoppers (=spittlebugs). Both armored and soft scales as well as the eggs of plant bugs and lace bugs are next most frequently attacked. Relatively few eggs of insects that undergo complete metamorphosis, or holometabolous development, are attacked, however, of those the most common families include weevils and predaceous diving beetles! (from: Chalcidoidea Database) A close-up view of a mymarid wasp, possibly a Mymar species, trapped on a yellow sticky card. Note that the length of the antennae are longer than the head and thorax and combined. Hind wings are present but reduced to narrow filaments. In our area, wasps in this genus are egg parastioids of leafhoppers and planthoppers. Photo: R.Waterworth, UMD A photo of the same mymarid specimen under the lowest magnification. For scale, there is a dance fly (left) and a house fly (right) below. Photo: R. Waterworth There are many examples of the deliberate importation of mymarid wasps to areas invaded by serious exotic agricultural pests. This method of pest management is referred to as classical biological control. In a recent 7

8 case, glassy-winged sharpshooter (a large leafhopper that feeds on xylem) had invaded Tahiti and threatened agriculture and native biodiversity. Densities of nymphs and adults were so large that their excretions literally rained from the sky. A local French name for this pest was mouche pisseuse or pissing fly. After the introduction of a mymarid wasp imported for its control, populations of sharpshooters declined by 90% within six months of the final release (Grandgirard et al. 2008). Now that s good biological control! Closer to home, mymarids are also primary parasitoids of potato leafhopper. While this species is a key pest of nurseries, it also is a significant problem in alfalfa. Work with mymarids in July 1994 demonstrated that nearly 70% of leafhopper eggs were parasitized (Lovinger et al. 2000). Female wasps located eggs by walking along alfalfa stems and laying a single egg within the egg of the leafhopper. The developing larvae of the wasps then feed on the contents of the egg, and leafhopper nymphs fail to hatch. So remember, all black dots are not created equal and look closely (very closely in the case of mymarids). Some are species of important biological control agents. Weed of the Week By: Chuck Schuster Geranium carolinianum (Carolina geranium, wild geranium) is found throughout the United States most often as a biennial, but it can also be a winter or summer annual. Starting from a basal rosette, the stem will elongate and have several branches. This weed has a shallow taproot with a fibrous support system. Stems will branch often and grow erect up to 24 inches in height. The stem varies in color from a pink to red, and will be densely hairy. Leaves are hairy on both upper and lower surfaces, alternate near the base, but become opposite above, round in appearance, palmate (like a hand), and divided into 5 to 9 segments, with each segment being toothed or lobed. The flowers are white to pink in color, found in groups of two or more clusters at the tips of branches, and contain 5 petals. Control of this weed can be obtained using many of the broadleaf herbicides in turf, and using product combinations containing trifluralin + isoxaben (Snapshot) as a pre emergent in landscapes. Carolina geranium has palmate leaves and a shallow taproot Photos: Chuck Schuster, UMD 8

9 Plant of the Week By: Ginny Rosenkranz Oenothera fruticosa (Southern sundrop) is a native herbaceous perennial in the evening primrose family. Plants grow inches tall and have bright green lance-shaped leaves and a hairy stem. Unlike Ozark sundrops, Southern sundrops are upright clump forming plants rather than sprawling, and produce terminal clusters of bright yellow flowers in May, June and sometimes to July. Each flower starts out as a red bud which opens to flowers that are 2 inches wide with 4 sunny yellow petals and bright yellow stamens. Flowers are short-lived, but as the flowers bloom in succession, the plant will show off their bright yellow flowers for almost 2 months. Sphinx moths and other moths, ruby throated hummingbirds, and bees pollinate the flowers or enjoy their nectar. The flowers are followed by club-shaped brown seed capsules. The plants grow and flower best in full sun, but will tolerate some shade. They prefer average to moderately fertile, medium well drained soils. Southern sundrops are tolerant of poor sandy or shallow rocky soils, salt, deer and cold tolerant from USDA zones 4-8. In winter, the basal leaves are evergreen reddish rosettes. Plants spread slowly and combine well with Asclepias tuberosa (butterfly weed), Coreopsis, Liatris and summer phlox. An old fashioned, pass-along plant that is coming back into popularity with the renaissance of native plants, Southern sundrop has no serious insect or disease pests. Southern sundrop plants produce bright yellow flowers for several months Photo: Ginny Rosenkranz, UMD Plant Phenology Indicators PLANT PLANT STAGE (Bud with color, LOCATION First bloom, Full bloom, First leaf) Asclepias tuberosa Bud Ellicott City (June 10) Cotinus coggygrias First bloom Glenelg (June 7) Pycnanthemum tenuifolium First bloom Ellicott City (June 7) Salvia officinalis First bloom Ellicott City (June 7) Stachys byzantina (lamb s ear) First bloom Ellicott City (June 7) Stewartia pseudocamellia First bloom Ellicott City (June 6) 9

10 Degree Days (As of June 8) Annapolis Naval Academy (KNAK) 846 Baltimore, MD (KBWI) 846 College Park (KCGS) 839 Dulles Airport (KIAD) 861 Ellicott City (E3247) 822 Fairfax, VA (D4092) 986 Frederick (KFDK) 714 Greater Cumberland Reg (KCBE) 801 Gaithersburg (KGAI) 741 Martinsburg, WV (C1672) 785 Natl Arboretum.Reagan Natl (KDCA) 1060 Rockville (C2057) 1017 Salisbury/Ocean City (KSBY) 867 St. Mary s City (St. Inigoes, MD-KNUI) 1009 Westminster (KDMW) 852 Important Note: We are now using the Online Phenology and Degree-Day Models site. Use the following information to calculate GDD for your site at the Online Phenology and Degree-Day Models site: Select your location from the map Model Category: All models Select Degree-day calculator Thresholds in: Fahrenheit F Lower: 50 Upper: 95 Calculation type: simple average/growing dds Start: Jan 1 Once you know the GDD and / or plant phenological indicators (PPI, what plants are blooming) in your location, you can go to the Pest Predictive Calendar to determine what pests you can expect to be active soon in that location. Biocontrol Conference for Nursery and Greenhouse Growers By: Stanton Gill We are organizing a Biocontrol conference for August 18, 2016, so mark your calendar. We will put out a complete schedule of topics and speakers in June. The location will be Brookside Gardens in Wheaton, Maryland. We will be bringing in speakers from the Ontario Experiment Station, the Connecticut Experiment Station, BioWorks from Florida, local growers who have adopted biocontrol options, and several University of Maryland Extension faculty. Each will talk about their latest research in biological control options in the nursery, greenhouse and landscape. This program is co-sponsored with MNLGA and they will handle registration for this conference. A New Biofungicide: Olympic Horticulture Products announced last week that they are marketing a biofungicide/bactericide under the name Triathlon. It is an aqueous solution material, which colonizes plant surfaces and prevents the establishment of disease causing fungi and bacteria. With the active ingredient, Bacillus amyloliquefaciens, Triathlon BA provides preventive control of many foliar and soil-borne diseases such as botrytis, powdery mildew, downy mildew, rusts, leaf spots, alternaria, pythium, phytophthora, rhizoctonia, fusarium and bacterial spot. Chris Hayes, BioWorks, will cover this product and others for biocontrol of fungal diseases at the August 18th Biocontrol Conference. Drones and IPM By: Stanton Gill In the Monday issue of The Washington Post they had an article entitled Even Cowboys Get the Drones. The article talked about how drones are being used in Australia on the range to monitor cattle herds instead of using on-the-ground cowboys. This article ties into where we are taking the IPM program. On June 29 we are working with MNLGA in holding an evening session at Milkhouse Brewery in Mt. Airy, MD where we will have a talk on using drones in the horticulture industry. There will also be a live demonstration of drones at this site. The session will be held from 5:00 p.mn. until dark. Visit the MNLGA website to register for this interesting and hopefully, fun evening event. 10

11 2016 Summer Conferences MNLGA Nursery Field Day June 23, 2016 Location: Angelica Nurseries Locust Grove Road Kennedyville, Maryland Contact: Register online at MNLGA Hops and Drones June 29, 2016, 4:00 PM - 8:00 PM Location: Milkhouse Brewery at Stillpoint Farm 8253 Dollyhyde Road Mt. Airy, MD Contact: , office@mnlga.org Register online at MNLGA Maryland Christmas Tree Association Summer Meeting Saturday June 25, 2016 at Thomas Tree Farm, 3501 Hanover Pike, Manchester, MD For info: wayne@thomastreefarm.com Hands-on Perennials Diagnostic Workshop July 20, 2016 Location: Perennial Farm Glen Arm Road Glen Arm, MD Contact: , office@mnlga.org Biological Control for Greenhouses and Nurseries August 18, 2016 Location: Brookside Gardens, 1800 Glenallan Avenue, Wheaton, MD Contact: , office@mnlga.org 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.