TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture August 21, 2015 In This Issue... - Mite Activity - Disruption pheromones - Carrion beetle - Grubs in turf - Hemlock wooly adelgid - Zelkova branches dropping - Curled roseslug sawfly - Hedgehog gall on oak - White prunicola scale - Tuliptree scale - Insects on butterflyweed 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. 301-596-9413 (office) or 410-868-9400 (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) Hot Weather and Mite Activity By: Stanton Gill, University of Maryland Extension We have gone most of the summer without reporting on spider mites. From April through July we had frequent enough rain storms that suppressed most mite populations. The outcome has been that we saw just a few isolated cases in nurseries and landscapes in the first ¾ of the summer. Now that we have moved into hot and dry weather the spider mite populations are flourishing. We are finding two-spotted spider Spider mites cause yellow stippling and distortion on foliage mites on a wide range of plants including many herbaceous perennials. Adults of two-spotted spider mites have two dark spots on the body. Southern red mites are being found on mainly oriental holly species. Southern red mites are reddish brown and darker than most red spider mites found on woody ornamentals. The southern red mite is usually active in spring and again in the late summer when we start to have cool nights and warm days. The southern red mite can also be found on boxwood, hibiscus and cotoneaster. Monitoring: Use a light colored paper on a clipboard and place it under branches and tap them sharply. The mites, if present, should be easily seen running around on the light colored surface. Control: There are several products labeled for mite control including Akari, Aza-Direct, Abamectin (Avid), and Forbid.
Using Disruption Pheromones By: Stanton Gill, University of Maryland Extension Last week I mentioned I would talk about using disruption pheromones to deal with certain insects. Back in late spring I wrote an article about controlling the peachtree borer in cherry laurel. With the growing popularity of cherry laurels we have seen a large increase in damage form peachtree borer. Robin Rosetta, Oregon University Extension, picked up on my article and sent me an e-mail saying that they had been working with a nursery in Oregon that was trying to control peachtree borer with disruption pheromones. Pheromones are airborne chemicals which are emitted to attract the opposite sex. Pheromones are believed to be detected on an instinctual, subconscious level. In other words, you don t know that you re receiving them. There is a commercial product called Isomate which is an insect pheromone that is impregnated into a plastic stick with a metal core called a twist tie. The plastic twist tie is twisted around tree branches at approximately 4 to 10 ft high and about 9 ft apart in the nursery. The twist tie emits pheromone for 120-180 days. The pheromone twist ties come containing chemicals that mimic the naturally produced pheromone of the female insect species. Isomate is a brand name for several different pheromones for specific insect species. We have used the twist ties for peachtree borer and another for oriental fruit moth. I obtained peachtree disruption pheromone from Isomate Company this spring. The nursery that was planning to work with us on this project made an application of an insecticide that would negate our measuring its impact. I decided to deploy the pheromone at my orchard in Westminster since I suffered damage on cherry and plum trees with 21 trees hit with peachtree borer in 2014. The Isomate disruption pheromone was placed out in early June covering two acres of growing area. I just finished examining the trees on August 16 and found 3 peachtree borer hits on the trees in 2015. I spoke with the IPM scout from Hollabaugh Orchard in Biglerville, PA and he said they had been using the peachtree disruption pheromone for over 3 years and they had dramatically reduced the incidence of peachtree borer damage in their orchard. He said it was expensive, but it had cut their losses tremendously. I think this disruption pheromone has potential for use in Maryland nurseries that are troubled with peachtree borer in cherry laurel, peaches or ornamental plums. If you want to work with me in 2016, contact me at sgill@u,md.edu or 410-868-9400. I have been using the Isomate pheromone dispensers for oriental fruit moth and codling moth in my orchard since 2011 and I have experienced very little damage from either of these pests. The scout at Hollabaugh s orchard said they had been using the oriental fruit moth and codling moth disruption pheromone for over 7 years and it was very effective in reducing their damage from these two pest. The use of disruption pheromones would be best done in a nursery setting. I don t think it would be as cost effective in a residential landscape, but I could be wrong. Carrion Beetle Jason Kopp, Turf Equipment Supply, found a carrion beetle active in Frederick this week. The adult beetles lay eggs on dead animals and the larvae consume the carrion. They are also pollinators of pawpaw trees. Carrion beetles are spotted periodically in landscapes and other settings Photo: Jason Kopp, Turf Equipment Supply Grubs in Turf Mark Schlossberg, ProLawn Plus, Inc., reported finding early instar scarab beetle grubs in turf in Timonium today. We have been seeing Scoliid wasps very active flying over the turf here at the research center all week. 2
Hemlock Wooly Adelgid By: Stanton Gill, University of Maryland Extension Mark Schlossberg, ProLawn Plus, Inc., sent a picture of hemlock wooly adelgid this week. The females are starting to swell up as we move into late August. The hemlock woolly adelgid (HWA) (Adelges tsugae) is a destructive, non-native pest of hemlock trees. HWA inserts its long, piercing-sucking mouthparts into the base of hemlock needles and feeds on nutrients stored in the xylem ray cells. In addition to removing the tree s nutrients, the adel gid is thought to cause a hypersensitive response that restricts water transport in the tree. Other stress factors can intensify these effects, causing decline and death of trees of all age classes. The U.S. National Arboretum has been working on crossing the native hemlock with hemlocks from Asia and at this point are getting closer to releasing a hybrid plant that may show resistance to this pest. If your customers hav infested hemlocks, a root flair application of dinotefuran or imidacloprid should provide control. Curled Roseslug Sawfly Jessica Frakes, Thrive, Inc., is finding the second generation of curled roseslug sawfly on roses in D.C. There are three species found in this area: roseslug sawfly, curled roseslug sawfly and bristly roseslug sawfly. Feeding by later instars creates larger holes and can defoliate plants. Control: Conserve or Orthene can be used to control the larvae Look for the second generation of hemlock wooly adelgid crawlers in late September to early October Photo: Mark Schlossberg, ProLawn Plus, Inc. Zelkova Branches Dropping By: Stanton Gill, University of Maryland Extension Bob from Carroll Tree called in to report that he is finding a large number of zelkova branches litttering the ground around zelkova trees in Baltimore County. We had a report of this situation three years ago from Damian Varga from Scientific Plant Services. Each of the branches had chewed areas at the end of the branches. Squirrels like to cut off small branches 12 18 in length for their nests at this time of year and zelkova trees are one of their preferred species to use. Many of the branches they cut fall to the ground in August and early September. At least you know that it is not insect or disease activity. Curled roseslug sawflies curl themsleves up when not feeding to blend in with the foliage on roses Hedgehog Gall There are many galls that develop on oaks. Greg Clontz, Mainscapes, brought in an oak leaf with hedgehog gall. The gall is caused by a tiny cynipid wasp. These galls do not affect the overall health of the tree. 3
White Prunicola Scale (WPS), Pseudaulacaspis prunicola (armored scale) Monitoring WPS on Prunus subhirtella Autumnalis in Laytonsville on Thursday, August 20 found mostly 3 rd instar females without eggs. However, there was a small population with eggs suggesting it is getting close to the time that 3 rd generation crawlers will be active. Based on our research on monitoring WPS, we predict crawler activity to be when the Degree Days are near 3043 (maybe within a week or so). The Degree Day accumulations in Laytonsville as of August 20 were 2856DD. Monitoring: Closely examine preferred host plants, Prunus species (especially Japanese flowering cherry), Ligustrum spp. (privet), Euonymus spp., and Syringa spp. (lilac). WPS has 3 generations per year. You are looking for the white male and female covers on the bark of branches and trunks. The adult female Small populations of white prunicola scale have eggs so it s getting close to the time of crawler activity Photo: Nancy Harding, UMD wax cover has a distinctive fried egg appearance and clusters of males give the bark a fluffy appearance. Crawlers (1 st instar) are salmon-colored. Note: white peach scale looks very similar to white prunicola scale but they have different host plants. Control: When crawlers are active, apply pyriproxyfen (Distance) or buprofezin (Talus) mixed with 0.5-1% horticultural oil for control. No control should be applied until you see crawler activity. Tuliptree Scale, Toumeyella liriodendra (soft scale) Monitoring tuliptree scale on magnolias in Adamstown found plump large 3 rd instar females without eggs indicating there is still some time before crawlers will be active. This native soft scale insect prefers tuliptree (Liriodendron) and magnolia. There is one generation of the tuliptree scale each year. We will continue to monitor this scale and report when there is crawler activity. Insects on Butterflyweed Leslie Beal Bloom is finding milkweed bugs and monarch caterpillars on Asclepias tuberosa this week. Leslie noted that this sighting is her first one for the monarch caterpillar. Here at the research center in Ellicott City, we have been seeing caterpillars and butterflies off and on since late July. Milkweed species attract many insects including monarch caterpillars and milkweed bugs; they are also a favorite of oleander aphids (a bright orange to yellow aphid) Photo: Leslie Beal Bloom 4
Beneficial of the Week By: Paula Shrewsbury, University of Maryland The Iconic Monarch Butterflies Monarch butterflies, Danaus plexippus (family: Nymphalidae) are one of the most well-known butterflies in North America. There are few children who make it through school without learning the lifecycle of these beautiful and interesting iconic butterflies. There are Citizen Science projects and other programs with the goal of monitoring and conserving monarchs. Everyone loves monarchs and rightly so! In addition, monarch adults provide pollination services and the caterpillars are food for other organisms. Given all of this I think they qualify as a beneficial. Monarch butterflies are often thought to occur only in North America. However, its range includes Hawaii, Australia, New Zealand, Spain, and some Oceanic islands. Other species of monarchs occur in other parts of the world. The monarch s wingspan is about 8-10 mm and males are slightly larger than females. The upper wings are orange with black veins and margins, and white spots are located in the black margins. In males the black veins in the hind wings are narrower than those in females. The viceroy butterfly looks similar in color and pattern to the monarch. These butterflies are an example of Műllerian mimicry. Both species share similar predators, both are toxic and both present similar warning coloration patterns of orange and black. This mimicry is a form of protection from predators. Predators learn twice as fast that orange and black butterflies taste bad! Larvae vary in color patterns as they molt from 1 st instar to 5 th instar. In general, they are striped with transverse bands of yellow, black, and white. They have 2 pairs of black stink horns, one pair on the thorax and the other near the end of the abdomen. The chrysalis or pupa is green with a golden, metallic appearance. Adult monarchs feed on nectar from a wide range of native and non-native flowering plants. However, monarch larvae are specialists and feed only on milkweed (Asclepias spp.). There are several species of milkweed that occur in the wild or that can be purchased commercially. Some species used by monarch caterpillars include common milkweed (A. syriaca), butterfly weed (A. tuberosa), and swamp milkweed (A. incarnata). Milkweeds contain cardenolides which are sequestered by the monarch caterpillar and gives it a nasty taste that deters predators from eating them. Monarchs have an amazing lifecycle that involves multiple generations and migration across miles. In North America (NA) there are two populations in general. There is the eastern NA population that overwinters in Mexico, and in the spring begins its seasonal migration to the north toward southern Canada traveling thousands of miles. Monarchs undergo multiple generations during this long journey. In the late summer fall monarchs begin their migration back to their overwintering habitat in Mexico. There is also a western NA population that migrates between sites in California. Last winter I was fortunate enough to visit one of the overwintering roosts of monarchs in Monterey, CA. A truly amazing site that I recommend you all put on your bucket list to experience. 5
You have likely heard discussions regarding monarch decline. Anecdotal observations and monitoring data indicate there has been a long term decline in monarch populations since about the mid to late 1990 s. Monarch populations in their overwintering habitat in Mexico are now at their lowest numbers since data started to be collected and recorded about 20 years ago. There has been much effort towards identifying causes of monarch decline. Like most of these situations it does not appear to be just one factor. Factors include destruction of overwintering habitat, the adoption of herbicide (glyphosate) tolerant crops, infection by the disease Ophryocystis elektroscirrha, and parasitism by a tachinid fly, Lespesia archippivora. There is evidence that suggests the use of tropical milkweed, A. curassavica, may also play a role in monarch decline. There are numerous environmental and conservation groups who implement a number of projects to monitor and conserve monarch populations. A quick search of the internet can direct you towards these groups. You may want to learn more about monarch decline and participate in activities towards the conservation of monarchs. One of the more straight forward practices you can do to conserve monarchs is to plant flowering plants for the adult monarchs and milkweed (Asclepias spp.) for the caterpillars in your landscapes. Monarch larvae prefer some species of Asclepias to others so be sure to do a little research before purchasing and planting milkweed. For more detailed information on monarch butterflies and their conservation go to: http://www.monarchwatch. org/ Weed of the Week By: Chuck Schuster, University of Maryland Extension The unusual weather seems to be pushing thistle do thrive this year. I have been asked why it is not responding to herbicides, why it is so prolific, and most of all, is it really a problem. Musk thistle, also known as nodding thistle, Carduus nutans, is an erect biennial that can be found throughout this region. This weed can grow to 6.5 feet in total height, with seedling leaves being from.25 to.5 inches long and up to.25 inch wide. Seedling leaves are found mostly without hairs and the plant will establish a rosette growth habit quickly. The root system is a large thick taproot, which is hollow near the surface. The easy to identify characteristics include an erect, spiny leaf, deeply lobed leaves and large flowers that are from pink to purple in color. Similar to Canada thistle, but it lacks rhizomes and musk thistle will take on a rosette growth habit which Canada thistle does not. It is allso similar to bull thistle, but musk thistle lacks hairs on the upper leaf blade. Treating to control musk thistle cannot be done in a casual nature. Pulling or cutting off plants does not provide control. Control can be accomplished by using many broadleaf post emergent herbicides. In turf areas 2,4-D with chlorsulfuron, and dicamba are effective. In beds and nursery rows bentazon (Basagran), and glyphosate products are effective. When applying a 2% solution of glyphosate (e.g., Roundup) or triclopyr (e.g., Garlon) and water, wet all leaves and stems. Timing is very important; treatments should be applied during the rosette stage or prior to flowering, fall application after Musk thistle has been thriving this season Photo: James R. Allison, Georgia Department of Natural Resources, Bugwood.org repeated mowing gives the best control. Use of glyphosate products should be limited to early in the season in a nursery with a carefully placed spray. Cultural controls would include preventing seed formation, fertility management, and maintaining a dense turf. Be mindful of nitrogen applications, as excess nitrogen will increase weed growth. A high mowing height to allow shading of newly germinating seeds is an effective management tool in turf. 6
Plant of the Week By: Ginny Rosenkranz, University of Maryland Extension Hydrangea paniculata Sweet Summer is a compact cultivar of panicle hydrangea that grows only 4-5 feet tall and 4-6 feet wide. One of the most winter hardy hydrangea, they grow in USDA zone 3-9 and bloom on the current season s growth so plants can be pruned in late winter or early spring. They are tolerant of drought (once established), heat, shade, frost and air pollution. Sweet Summer can be grown as a standard, but flowers best if grown with 5-10 main branches. The cone-shaped flower clusters have wide bases, grow 4-5 inches long, and are covered with large, infertile flowers with the tiny fertile flowers tucked within the large cone. The flowers emerge creamy white and open from the bottom continuing up to the top. The white flowers mature to a Hydrangea paniculata Sweet Summer provides shades of pink and white in the landscape Photos: Ginny Rosenkranz, UMD soft pink, so the flower cluster has light pink on the bottom of the 5 inch flower cluster and is topped with pure creamy white flowers. The white and pink flowers are held on strong straight upright stems and begin to bloom in July and last until late fall. Flowers can be picked as fresh flowers or cut for dried flowers, while the flowers left on the plant will naturally turn a dusky pink. This cultivar is from Ball Ornamental and can be used in a mixed border planting, as a mass planting, in an open woodland garden or as a specimen plant. Occasional pests include aphids, mites, bud blight, bacterial wilt, leaf spot, rust and powdery mildew. Degree Days (As of August 20) 2015 2014 2013 2015 2014 2013 Baltimore, MD (BWI) 2886 2593 2727 Dulles Airport 2845 2473 2745 Frostburg, MD 1976 1629 1724 Martinsburg, WV 2702 2493 2535 National Arboretum 3515 3174 3123 Reagan National 3515 3174 3123 Salisbury 2820 2855 3024 St. Mary s City 2936 2680 2873 To check degree day (DD) accumulations in your local area go to: http://www.yourweekendview.com/outlook/agriculture/growing-degree-days/. 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. Montgomery College - FAll 2015 Courses with Instructors from University of Maryland Extension For more information: Steve Dubik, 240-567-7803 LNTP 190 Pesticide Use & Safety 2 semester hours (Class ends on Oct. 25) Prepare for the pesticide application certification exam through a thorough understanding of the principles of pest control, including pesticide labeling, regulations and proper handling. Thursday, 6:00-9:30 p.m. CRN 23920 Instructor: Chuck Schuster, University of Maryland Extension LNTP 215 Pest Management 3 semester hours Hone your pest management skills with Stanton Gill. Explore the identification of key pests, their life cycles and control methods, with emphasis on integrated pest management strategies. Wednesday, 6:00-9:30 p.m. CRN 24445, CRN 24447 Lab Includes option Saturday field trip(s) and is approved by MDA to prepare professionals for pesticide application certification in Category 3. Instructor: Stanton Gill, University of Maryland Extension 7
Upcoming Conferences: LCA Hands-on Training Seminar September 16, 2015 Location: Johns Hopkins University, Montgomery County Campus 4 th Annual TreesMatter Symposium November 4, 2015 Location: Silver Spring Civic Center, Silver Spring, MD Interiorscape Conference October 1, 2015 Location: Rawlings Conservatory, Baltimore, MD Community Forestry Workshop October 2, 2015 Location: Carroll Community College, Westminster, MD http://www.westgov.com/182/forestryworkshop CONTRIBUTORS: Stanton Gill Extension Specialist sgill@umd.edu 410-868-9400 (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.