TPM/IPM Weekly Report

TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture May 4, 2012 In This Issue... - Leaf gall on camellia - Japanese maple scale webinar - Scale update - Needle loss on white pine - Powdery mildew - Sawflies on Lysimachia - Aphids - Cankerworms - Birch problems - Leafroller - Lilac borer - Ticks - Euonymus caterpillar - Wool sower galls - Hawthorn leafminer - Plum curculio - Azalea plant bug (predator) Beneficial of the Week Plant of the Week Phenology Degree Days Conferences Integrated Pest Management for Commercial Horticulture www.ipmnet.umd.edu 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. 301-596-9413 (office) or 410-868-9400 (cell) Regular Contributors: Pest and Beneficial Insect Information: Stanton Gill and Paula Shrewsbury (Extension Specialists) and Brian Clark (Extension Educator, Prince George s County) 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 (Regional Specialist, Wye Research & Education Center) Design, Layout and Editing: Suzanne Klick (Technician, CMREC) Leaf Gall on Camellia Doris Koehler of Branches Tree Experts sent in this lovely photo of leaf gall on camellia, caused by the fungus Exobasidium camelliae. We described this disease in last week s newsletter, but this photo shows the yellowish leaf symptoms very nicely. Leaf gall on camellia Photo: Doris Koehler, Branches Tree Experts Webinar on Japanese Maple Scale On Thursday, May 3, I (Paula) presented a webinar on JMS biology and management. Many people could not listen in at that time. The webinar will be available on-line (it will take a couple of days) at the web site listed below and you can watch it at your leisure. This webinar is part of an IPM webinar series. You may find webinars on other topics of interest on the website too (for example ambrosia beetles, box blight). http://ecoipm.com/ipm-webinar/

Scale Crawler Emergence Update John Speaker brought in several branch samples to our lab at CMREC this Wednesday. The samples were from nurseries on the Eastern Shore. Here is what we found: Minute cypress scale: Many females with eggs and a few with the first crawlers emerging. Control: It is time for Distance or Talus applications. Japanese maple scale: Females were present, but no eggs or crawlers found yet on Burford holly and blue holly. Paula Shrewsbury and Nancy Harding checked maples in College Park that have Japanese maple scale on Wednesday, May 2nd. Like last week, they continued to see adult females with eggs, but NO crawlers as Minute cypress scale of yet. The degree day (DD) monitor on campus reports 575 DD (Jan. 1 May 1). Weatherchannel.com reports 548 DD for College Park. Other areas of the state report females present but no eggs yet. They are cooler than College Park. Data from JMS studies, based on 3 years of studies, indicates 1st generation crawler activity should start around 815 DD. Remember DD are guidelines that tell you when you should be closely monitoring your insects and plants. Control: Applications of 0.5-1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) should be made when crawlers are detected. This 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. Maskell scale: The females were on arborvitae and eggs were visible as were many crawlers. Control: Soil applications of dinotefuran (Safari, Transtect) or buprofezin (Talus) or pryriproxyfen (Distance) applied as a foliar spray will control this scale. Calico scale: Jan van Zutphen, City of Annapolis, sent photos of honey locust trees from a site in Anne Arundel County with a heavy infestation of calico scale that was causing tree dieback. The females were swelling up quite a bit. Control: When crawlers are out, use pryriproxyfen (Distance) or buprofezin (Talus) with 0.5 1% oil. Another option for controlling soft scale is to use a soil injection or soil drench of a systemic insecticide, such as imidacloprid (Merit) or dinotefuran (Safari, Transtect). This material takes 30-60 days to be taken up by the Calico scale is a soft scale that produces copious amounts of honeydew plant before it begins to control the scale. Photo: Jan van Zutphen, City of Annapolis Marie Rojas reported the following scales this week: Cottony camelia scale: Marie found eggs under the wax on Dragon Lady hollies. Todd Franklin, The Brickman Group, reported crawlers on hollies in Washington D.C. last week. Control: When crawlers are active, treat with pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5-1% horticultural oil. Pine needle scale: Marie found eggs under the female scale covers on white pine. Control: Use 0.5 1% horticultural oil and pyriproxyfen (Distance) or buprofezin (Talus) for crawlers. Dinotefuran (Safari, Transtect) is reported to control this scale. 2 Pine needle scale

Needle Loss on White Pine We have received several samples in the clinic of white pines with discoloration of some of last year s needles just below this year s elongating shoots. This symptom is also being observed on white pines throughout the Mid-Atlantic region, based on comments from other diagnosticians. There is no indication of insect pests or disease associated with this needle drop. This may be a response to environmental stress, related to temperature and moisture fluctuations this spring. The new growth on affected trees appears to be normal, and the needle loss should be less noticeable once this year s foliage is mature. Keep an eye out for white pines showing these symptoms, and let us know if the trees grow out of the problem or if current year foliage also shows discoloration later this season we d like to keep tabs on this situation. Powdery Mildew We continue to receive reports of powdery mildew on euonymus. Mark Schlossberg, ProLawn Plus, Inc., reported infection in Pikesville. Sunny, warm days and cool nights provide favorable conditions for this disease. Sawflies on Lysimachia (Creeping Jenny) Marie Rojas reported this week that sawflies are feeding on creeping jenny (Lysimachia) in a client s yard in Laytonsville on April 30. She noted that it continues the three-week-plus early trend of pest activity. Control: Conserve can be used for control. Powdery mildew on euonymus Photo: Mark Schlossberg, ProLawn Plus, Inc. Aphids Marie Rojas, IPM Scout, is finding aphids in very high numbers on the growing tips of Rose of Sharon (Hibiscus). In the photo, note the little ants protecting them and lady bird beetle that feeds on the aphids. Ants provide protection to the aphids in return for honeydew. Dan Nowakowski, Elite Landscaping in New Jersey, sent in a photo of a winged aphid on a rose bud. We have had a few reports of aphids on roses as well recently. Sawfly larvae and damage on Lysimachia Photo: Marie Rojas, IPM Scout Winged aphid on rose Photo: Dan Nowakowski, Elite Landscaping 3 Aphids, ants and a ladybird beetle on hibiscus Photo: Marie Rojas

Cankerworms Chris Klimas, The Davey Tree Expert Company, Inc., reported that while in Richmond last week, he saw oak woodlots stripped by cankerworms and he has received reports of damage in McLean, VA and on the National Mall. So far this year, we have not received reports of cankerworm activity in Maryland. In the past, we have noted heavy infestations concentrated in areas of Anne Arundel County. Is anyone seeing cankerworm activity in Maryland? Please let us know the location if you see the caterpillars and feeding damage. Monitoring: The larvae are light green to sometimes dark brownish green. The light green forms have white lines along the body. Brown forms have a broad black stripe on the back. Fall cankerworms larvae have 3 pairs of prolegs at the end of the abdomen whereas spring cankerworms only have two. The adult female is wingless and lays eggs in the fall. Control: Bt or Conserve. Dark brown and green forms of cankerworms Problems With Fall Planted Birch Problems Luke Hallman asked if any other people are finding a lot of dieback on fall-planted river birches this season. If so, contact me (Stanton) at Sgill@umd.edu. Leaf Rollers on Witchhazel Amanda Laudwein, University of Maryland Extension, reported leaf roller activity on witchhazel this week. This small caterpillar rolls the leaves into cylinders and stays within these rolled leaves. Lilac Borer We continue to find adult males in the baited pheromone traps this week. Control: Permethrin or bifenthrin applied to susceptible stems. Ticks Let us know what you are seeing on tick activity in your area. We asked several nursery people this week and all said they are seeing fewer ticks this season. We are interested in whether everyone is seeing reduced tick activity. Contact us at Sgill@umd.edu. Thanks Euonymus Caterpillar (Yponomeuta cagnagella) Marty Adams, Bartlett Tree Experts, reported euonymus caterpillar activity on Euonymus Manhattan in Columbia on May 4. This caterpillar is not the same one as the euonymus leaf-notcher caterpillar reported earlier. The euonymus caterpillar produces webbing over the ends of branches in which it feeds and has black spots, not stripes. They can defoliate plants very quickly. Control: Conserve will control the larvae. Pruning out infested branch tips is another option. 4

Wool Sower Galls We received another report of wool sower galls this week. Colin Stewart, USDA, is seeing them in Fairfax County, Virginia and Huntingtown, MD (Calvert County). Wool sower gall Photo: Colin Stewart, USDA Hawthorn Leafminer Craig Greco, Yardbirds, Inc., found leafminers damaging hawthorn this week. The adults emerge when serviceberry and flowering quince bloom. Eggs will hatch a few days after being laid within the leaves. Then, larvae will leave their mines and pupate within the soil. Overwintering will also take place in the soil. Hawthorn leafminers only have one generation a year. Control: Contact controls should be applied around the first of May. Monitor trees for adult activity as well as egg laying scars on the leaves. Chemical treatment can be applied in the fall or early spring, using imidacloprid or Dinotefuran (Safari) or thiamethoxam (Flagship) to control hawthorn leafminer in spring. Hawthorn leafminer damage Photo: Craig Greco, Yardbirds, Inc. Plum Curculio The plum curculio weevil, Conotrachelus nenuphar, is active this week and the females will be laying eggs in apples, pears, plum, Beach plum especially, quince, peaches and cherries. The adult plum curculio is a small, hard-bodied, brownish-black snout beetle mottled with white and orange areas. It has 4 prominent black humps on its top surface. It is about 6 mm long, has a long snout, the end of which bears chewing mouthparts. The insect overwinters as an adult under debris. A small cavity is made in the fruit for the egg; then a crescent-shaped cut is made adjacent to the egg pocket. Fuzz on peaches makes it difficult to see this egg scar. The early feeding and egg-laying punctures can cause marked scarring and malformation of the fruit. Early feeding on the surface of peaches often causes severely deformed fruits known as cat-faced peaches. Larvae hatching from the eggs feed inside the fruit until they are fully grown. On some fruits, few if any of the young larvae survive to maturity if the fruits continue to grow on the tree. Larval feeding in apples can cause distortion of the fruit. Plum curculio damage on plums Control: If you are seeing this damage on the fruit, it is already too late to treat. If you need to protect home fruit, an application of Imidan can be applied. You have to kill the adult females before she deposits eggs into the fruit. If you miss this application, the crescent-shaped damage will appear on the fruit in late May and early June. Damaged fruit will often fall off the tree. 5

Azalea Plant Bug (Rhinocapsus vanduzeei) Colin Stewart, USDA, reported that azalea plant bug nymphs were active in Lorton, VA on May 1. The azalea plant bug is a predatory insect. He noted that they are most likely third instars. These nymphs are bright red, not much bigger than an adult thrips, and can (occasionally) bite. Azalea plant bug nymph Photo: Jim Baker, North Carolina State University, Bugwood.org Beneficial of the Week, Paula Shrewsbury Parasitoids and honeydew Although aphids are pest insects that feed on many ornamental plants they also have some more positive attributes. For example, populations of aphids often have a suite of natural enemies associated with them. Aphids actually help to attract and sustain natural enemies in landscapes and nurseries. Many of these natural enemies, such as lady beetles, flower fly larvae, wasp parasitoids that result in aphid mummies, and predatory fly midges use the aphids as food and then when the aphids are gone they move on to other herbivores in the landscape or nursery. Another way aphids benefit some natural enemies, particularly parasitic wasps, is with the honeydew they produce. This spring we have a profusion of aphids, and their honeydew, on a variety of plants. A beneficial wasp visits a leaf infested with aphids to get a quick carbohydrate fix. Photo: M. J. Raupp, UMD Why are aphids so abundant at this time of year and where does this honeydew come from? As plants break bud in spring to begin a new season of growth, production of new leaves and blossoms results in a steady flow of water and minerals from the roots to the shoots and the transport of nutritious sap within plants through a specialized vascular tissue called phloem. Phloem is a favorite feeding station for many types of sap-sucking insects including aphids. Phloem sap is relatively poor in nitrogen but high in carbohydrates. For aphids to obtain enough nitrogen for growth and development, large volumes of plant sap must be consumed. Excess residue of this extraction process is excreted by the aphid as a sweet sticky liquid called honeydew. Many parasitoid adults need high carbohydrate resources. Some parasitoids, as is often seen with ants, take advantage of the sugars in aphid honeydew (see image). While other sources of carbohydrates such as nectar from flowers are the primary source of carbohydrates for many beneficial insects, scientists agree that honeydew is an important food supplement for droves of good guys in your garden. Plant of the Week, Ginny Rosenkranz Correction from April 27, 2012 Report: Last week the picture was incorrectly identified as Viburnum acerifolium when it was in fact Viburnum opulus Roseum, a sterile cultivar of the European viburnum. The error was pointed out by John Fitzpatrick, Blue and Green, LLC, and Jil Swearingen, National Park Service. Viburnum acerifolium has flat clusters of yellow white fertile flowers while the old fashioned European snowball viburnum has the showy, 2-3 inch balls of pure white flowers that cover the plant in the early spring. Like many viburnums, the flowers of Viburnum opulus Roseum start off light green in color then mature to the pure snow white, and last for many weeks. The most serious pest of the European snowball viburnum, is the aphids that often cover the new growth and distort the leaves and stems. 6

Aquilegia, columbine, is a short-lived native herbaceous perennial that blooms in the spring and early summer in rich, moist, well drained soils and light dappled shade. The leaves are medium green, deeply notched, and fan-shaped. The flowers are held upright on stiff stems or are on slender stems that allow the flowers to nod in the lightest breeze. The actual flowers consist of 5 petals with a short broad 5-chambered trumpet in the front and 5 spurs that arch backwards from the trumpet. Some Aquilegia have straight spurs like the Rocky Mountain columbine; some have hooked spurs like the Alpine columbine from Switzerland; and others are curved like our native columbine, Aquilegia canadensis. The 5 sepals can be the same color as the petals, contrasting colors or pure white. There are many new hybrid columbine including the Songbird series which is known for richly colored flowers Aquilegia flower from the Songbird series Photo: Ginny Rosenkranz, UME including Cardinal with robin red-breasted red sepals that support the pure white petals. The 5-chambered trumpets are also a bright scarlet red. The flowers last more than the usual 3-4 weeks and are held up and nodding on 18-36 inch stems. The foliage forms clumps from 12-18 inches wide. Songbird columbine are hardy from USDA zone 3-9 and are as susceptible to the columbine leafminer as any other columbine. Plant Phenology: What s in bloom PLANT PLANT STAGE (Bud with color, First LOCATION bloom, Full bloom, First leaf) Clematis Westerplatte Full bloom (May 2) Silver Run Iris pseudacorus First bloom (May 1) Ellicott City Kalmia angustifilia Royal Dwarf First bloom (May 1) Silver Run Paulownia tomentosa Full bloom (May 2) Talbot County Rhododendron Home Bush Bud with color (May 2) Silver Run Rhododendron Marydel Rhododendron Gibraltar Full bloom (May 2) Silver Run Rhododendron Klondyke First bloom (May 2) Silver Run Sophora davidii Full bloom (May 2) Silver Run Staphylea trifolia Full bloom (May 2) Silver Run Styrax americanus Kankakee form Bud swell (May 2) Silver Run Syringa pubescens v julianae Hers Full bloom (May 2) Silver Run Degree Days (As of May 3) Baltimore, MD (BWI) 428 Dulles Airport 427 Frostburg, MD 241 Martinsburg, WV 394 National Arboretum 538 Reagan National 590 Salisbury 628 7

Upcoming Programs MAA Pest Walk May 17, 2012 Location: Brookside Gardens, Wheaton, MD Invasive Species Identification and Management Seminar May 23, 2012 9:30-3:15 Location: 12055 Government Center Parkway, Fairfax, VA Cost: Free, but registration is required. To register please go to: http://ffxpest.eventbrite.com Contact: Jack Baggett 703-324-5542, John.baggett@ fairfaxcounty.gov ASCFG Mid-Atlantic Regional Meeting June 18, 2012 Roost Flowers and Design Location: Virginia Beach, Virginia ascfg.org 2012 Perennial Plant Symposium July 4-10, 2012 Location: Boston, Massachusetts perennialplant.org OFA Short Course July 14-17, 2012 Location: Columbus, Ohio ofa.org OFA Perennial Production Conference September 10-12, 2012 Location: Grand Rapids, Michigan ofa.org MNLA Field Day June 21, 2012 Location: D.R. Snell Nursery, Union Bridge, MD Maryland Christmas Tree Association s Summer Meeting June 30, 2012 (Saturday) Location: Taylor Sines Woodlake Tree Farm, Oakland, MD Contact: 410-452-9793 CONTRIBUTORS: Stanton Gill Extension Specialist sgill@umd.edu Paula Shrewsbury Extension Specialist pshrewsb@umd.edu Karen Rane Plant Pathologist rane@umd.edu Chuck Schuster Extension Educator cfs@umd.edu Ginny Rosenkranz Extension Educator rosenkrnz@umd.edu David Clement Plant Pathologist hgic.umd.edu Andrew Ristvey Extension Specialist aristvey@umd.edu Brian Clark Extension Educator bpclark@umd.edu 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.