TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture October 5, 2012 In This Issue... - Hemlock elongate scale - Brown marmorated stink bug - Indian wax scale - Boxwood blight - Leafminer on oak - Twig girdler - Hairy bittercress - European hornets - Mushrooms - Powdery mildew Beneficial of the Week Weed of the Week Plant of the Week Degree Days Conferences College of Agriculture and Natural Resources Open House Saturday, October 6, 2012 Central Maryland Research and Education Center, Ellicott City, MD 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) Hemlock Elongate Scale I was examining a hemlock sample last week and found newly settled crawlers present. Hemlock elongate scale, sometimes known as fiorinia scale, is a serious armored scale insect pest of hemlock, Tsuga spp. The principal host plants include eastern hemlock, T. canadensis, Carolina hemlock, T. caroliniana, and northern Japanese hemlock, Hemlock elongate (fiorinia) scale on hemlock T. diversifolia, fir, Abies spp., and spruce, Picea spp. This key pest also feeds on cedar, Cedrus spp., Douglas-fir, Pseudotsuga menziesii, pine, Pinus spp., and yew, Taxus spp., but these are not preferred hosts. These less preferred host plants, if infested, are usually growing adjacent to infested hemlocks. This armored scale insect was unintentionally introduced into the United States from Japan. Look for the waxy covers of this scale on the lower needle surface. The flattened, elongate, light yellow brown to brownish orange waxy cover of the adult female is about 1.5 mm long. The adult female s body beneath the
waxy cover, eggs, and crawler stage are yellow. The white, waxy cover of the male is smaller. Feeding injury causes needles to drop prematurely giving the crown of an infested tree a thin appearance. Frequently, this key pest is found on the same hemlock tree with hemlock woolly adelgid, Adelges tsugae. There are multiple, often overlapping, generations of this scale. The settled crawlers (1st instars) can still be controlled with an application of Talus or Distance. Another option is to to use dinotefuran (Safari and Transtect). Brown Marmorated Stink Bugs We are getting more and more reports of brown marmorated stink bug activity around houses, restaurants, stores and structures that the bugs can find to infest. On Sunday I was attending a family wedding at Stronghold on Sugarloaf Mountain. It was an outdoor wedding in a garden. During the ceremony the bride and groom had to stop during the vows a couple of times to remove stink bugs from each other. The bride s white dress appeared to be very attractive to the stink bugs. The dark suit of the groom was also attractive. In the audience I saw people learning forward to flick off stink bugs on the shoulders of the person in front of them. In the evening a rain storm came in and the stink bugs migrated inside the wedding celebration tent and could be found all over the inside of the tent. I guess they wanted to celebrate as well. During the dancing people were flicking stink bugs off their clothes, and it became very stylish to flick a bug and dance. Everyone was tolerating the insects by the end of the evening. Let me know if you continue to see activity in your area of the state sgill@umd.edu. Indian Wax Scale Mark Schlossberg, ProLawn Plus, Inc., found indian wax scale on Magnolia sieboldii this week. Crawlers were active in June and July. This soft scale also feeds on Chinese and Japanese hollies, azaleas, pyracantha, euonymus, boxwood, flowering quince, camellia, pear, Close-up of red body underneath flipped scale cover BMSB are most active around buildings on warm afternoons azalea, persimmon, plum, and barberry. This scale is large Indian wax scale on Magnolia sieboldii Photo: Mark Schlossberg, ProLawn Plus, Inc. enough that its mere appearance is aesthetically unpleasing. Heavy populations can cause dieback of the infested plant. Monitoring: The adult females are red and covered with bright white gummy wax. Look for the large, very noticeable females overwintering on the stems. Control: Horticultural oil does not work well on this scale. Pyriproxyfen (Distance) or buprofezin (Talus) applied when crawlers are present works well. Imidacloprid (Merit in the landscape and Marathon in the nursery) can also be applied as a soil drench in April. It takes 30-60 days for uptake into the stems of the plant. A soil application of dinotefuran (Safari, Transtect) is uptaken in 2 3 weeks and should give good control. 2
New Boxwood Blight Detection in a Maryland Landscape We confirmed the presence of boxwood blight (caused by the fungus Calonectria pseudonaviculata, syn. Cylindrocladium pseudonaviculatum) in a landscape in Worcester County, MD last week. To our knowledge this is only the second detection of this disease in Maryland. The property has numerous mature boxwood in the gardens surrounding a house built in the 1850 s. The homeowner planted new, young boxwood near the mature plantings within the past year, and symptoms developed on both the young plants and mature shrubs during the spring and summer. Samples from this property were first submitted to the University of Delaware Plant Clinic where the initial diagnosis was made and Maryland Dept. of Ag officials were notified. We (K. Rane, UMD, Dick Bean and Mark Taylor, MDA) visited the site last week, and the symptoms were striking! Although there is currently no federal or MD state quarantine for this pathogen, the MDA is very interested in keeping the disease from spreading. Sanitation activities are underway to eliminate any off-site spread of infected plants or plant debris. If you suspect you see boxwood with boxwood blight, please call the University of Maryland Plant Diagnostic Lab (301-405-1611), or send me an email (rane@umd.edu). Key symptoms to look for are dark leaf spots and leaf drop, as well as small, black cankers on green stems. Scouting efforts should focus on landscapes where new boxwood have been installed within the past 2 years. Remember, pachysandra has recently been identified as another host for this disease. For more information, including photos of symptoms on boxwood and pachysandra, check out the Connecticut Ag Experiment Station website: http://www.ct.gov/caes/cwp/view.asp?a=3756&q=500388 Boxwood with severe defoliation from boxwood blight in a Worcester County, MD landscape. Photo: Karen Rane, UME Leaf symptoms of boxwood blight. Photo: Karen Rane, UME Leafminer on Oak Mark Schlossberg, ProLawn Plus, Inc., is reporting that leafminer larvae are actively feeding on white oak this week. If you see blotch mines on foliage, check for larvae. Leafminer on oak Photo: Mark Schlossberg, ProLawn Plus, Inc. 3
Twig Girdler Dawn Taft sent in photos of a twig girdler adult in the process of girdling an elm twig. The female beetle lays eggs in the twigs and then girdles the twig so it drops to the ground. The eggs hatch and the larvae overwinter in these fallen twigs. Look for large numbers of twigs under trees with damage that look likes beaver damage in miniature. Chemical control is often impractical so the best control option is to rake up and remove the fallen twigs. Twig girdler in the process of girdling an elm twig Photos: Dawn Taft Hairy Bittercress Mark Schlossberg is reporting that hairy bittercress is germinating now. Look for hairy bittercress in turf and landscape settings this fall. Control of this weed can be accomplished with the use of preemergent products that include oxadiazon (Ronstar), flumioxazin (Broadstar) or isoxaben (Gallery). Post emergent products can provide excellent control in turf, and they include 2,4D and triclopyr (Chaser), Metsulfuron (Blade). Be cautious near any landscape plantings. These products should provide ninety percent or greater control. Hairy bittercress Photo: Mark Schlossberg, ProLawn Plus, Inc. European Hornets Marty Adams noticed European hornets while picking a few paw paws on October 4. The hornets were buzzing all around the trees and on the ground. They were feeding heavily on the fruit both in the trees and on fruit that had fallen on the ground. They have also been flying around lights at night pretty heavily. At this time of year, the colonies have been producing males and females that mate, and the females become next year s queens. Only the overwintering queens survive in protected sites such as under loose bark, in tree cavities, and in wall voids of buildings. In the spring, the emerging queens establish new nests in aerial cavities, deposit eggs in cells they have constructed, and feed the first batch of larvae. The larvae mature, pupate in their cells, and then emerge as sterile female workers. European hornets are beneficial wasps. Food for their larvae include crickets, grasshoppers, large flies, caterpillars, and the workers of other wasp and hornet species. 4
Mushrooms As a result of recent rains, mushrooms are popping up in a lot of places. Connie Bowers, Garden Makeover Company, sent in a photos of two that she has seen. Powdery Mildew Powdery mildew is increasing on Monarda that is growing here at the research center in Ellicott City. Sunny days and cool nights provide ideal conditions for powdery mildew infection. Mushrooms after recent rains Photos: Connie Bowers, Garden Makeover Company Beneficial of the Week, Paula Shrewsbury Who is eating those stinking bugs? Well, it is that time of year again Beautiful fall days and brown marmorated stink bugs (BMSB) trying to work their way into buildings and homes. Although there are not enough natural enemies to eat all of the BMSB and keep them from entering your homes, it might make you feel better to know the natural enemies are working on it. In addition to the parasitic wasps that kill BMSB eggs that we discussed in an earlier newsletter (8/10/2012 issue) there are an abundant and diverse suite of predators that are filling themselves on BMSB adults and nymphs. These good guys include assassin bugs, particularly wheel bug adults and nymphs, which A robber fly feasting on the BMSB adult it just caught in flight Photo: M. J. Raupp, UMD enjoy sucking the life out of nymph and adult stink bugs. Jumping spiders are not intimidated by the size of BMSB. I have seen these spiders eating nymph and adult BMSB and often bugs that are twice the spider s size. 5 A wheel bug nymph, which is a species of assassin bug, with its sucking mouthpart imbedded in a BMSB adult Photo: C. Brodo, UMD
Praying mantids appear to be more abundant than ever and are having fun consuming BMSB. They always seem to start at the head end of the BMSB first. Lacewing larvae don t do so well on the eggs or late instars of BMSB but are quite efficient at feeding on early instar nymphs. Also very cool are the robber flies that catch their prey, in this case BMSB, on the fly. They catch a stink bug in flight and then land somewhere to enjoy their catch. We have been asked many times over this season where have all the stink bugs gone. Part of that answer (of course there is more to it) is that the abundance and diversity of natural enemies attacking BMSB seem to be increasing and having a greater impact on populations of BMSB. A praying mantid enjoys its BMSB meal but has to share with tiny opportunistic flies Photo: M. J. Raupp, UMD Weed of the Week, Chuck Schuster Virginia buttonweed, Diodia virginiana, is currently being found in many settings. This difficult-to-control perennial weed prefers moist to wet areas such as near downspouts or other moist sites. Leaves are opposite, on slightly hairy stems, with lance-shaped leaves that are one to two inches in length, by one inch in width. Leaves join the stem with a thin membrane which have up to three stipules that may appear to be long hairs. Stems will root at the nodes, usually growing along the soil in turf, but can grow upright as it is often found in the landscape. Flowers have four white petals and occur in the area between each leaf axil. The fruit is a small capsule, usually hairy, that contains two seeds. This weed will often have a yellow mottling later in the growing season as a result of a virus. This plant reproduces by seed, root and stem pieces. Because the stems help produce new plants, often mowers will move this weed from one site to another. It is similar to common buttonweed, but common buttonweed has a narrower leaf, an upright growth habit and will be much more hairy. Virginia buttonweed Cultural control includes removal of all plant parts hand Photos: Virginia Tech Weed ID Guide digging will be difficult. If possible, mitigate areas that have a tendency to be wet by improving drainage. Monitor irrigation to prevent excess moisture in turf and landscape settings. Clean equipment prior to moving from one site to another especially when working in areas where this weed has been found. Chemical control will require more than one application. This plant is difficult to control. In turf, use of 2, 4D, dicamba (Banvel, Clarity, and Vanquish), fluroxypyr (Spotlight) sulfosulfuron (Certainty) has been successful, but use caution with some of the more sensitive turf varieties. For the best control, applications should be made when Virginia buttonweed is in the 2-leaf to flower stage of growth. In landscape settings, products that contain glyphosate have been effective, but caution needs to be considered near exposed surface roots, suckers and wood stems. Repeated applications may still be necessary in many cases. Avoid using improperly composted material that has had this plant material added. Plant of the Week, Ginny Rosenkranz Aster novi-belgii, New York aster, can grow as tall as 6 feet, but the Wood s dwarf asters only top off around 2 feet tall. They begin to bloom around the end of September, giving them another common name of Michaelmas daisy. The dwarf aster Woods Blue has a rounded, mounding habit that becomes covered with tiny blue flowers in late September, and they bloom for almost 6 weeks. They grow best in full sun but do well in partial 6
shade with moist, well drained soils, and when established can handle some drought. Like all other asters, Woods Blue is resistant to deer and a butterfly magnate, pulling in all the Monarch butterflies before they fly south for the winter during the month of October. The plants are cold hardy from USDA zone 4-8 and can be planted in containers, in rock gardens or in the front of perennial beds. Because of their compact habit, these asters do not need staking and have resistance to both rust and mildew disease. Japanese beetles and lace bugs can also be a problem. Degree Days (As of October 4)* Aster novi-belgii Wood s Blue Photos: Ginny Rosenkranz, UME Baltimore, MD (BWI) 4180 Dulles Airport 4036 Frostburg, MD 2579 Martinsburg, WV 3737 National Arboretum 4732 Reagan National 4732 Salisbury 4328 *As of May 11, degree day calculations are from weather.com growing degree day calculations instead of NOAA min and max temperatures. To check degree day (DD) accumulations in your local area go to: http://www.weather.com/outdoors/agriculture/growingdegree-days/usmd0100 Fall Training Opportunities With fall fast approaching start marking you calendars with some upcoming training dates. In October, LCA is working with Karen Rane, David Clement, Mary Kay Malinoski and Chuck Schuster and myself in conducting a hands-on diagnostic session, Practical Diagnostic Techniques (and more!) for Landscape Managers, on October 17, 2012 at the Kenwood Country Club, Bethesda, MD. There is information on how to register at the LCA web site (http://www.lcamddcva.org/). On December 13, 2012, we will be holding the Pest Management Conference at Carroll Community College, Westminster, MD. A brochure will be available when the schedule is finalized. Upcoming Programs IPPS Eastern Region Annual Meeting October 10-13, 2012 Location: Brandywine Valley, Pennsylvania http://www.ippseastern.com LCA - Practical Diagnostic Techniques for Landscape Managers October 17, 2012 Location: Kenwood Country Club, Bethesda Contact: 301-948-0810, http://www.lcamddcva.org/ 2012 Delaware Ornamental and Turf Workshop November 14, 2012 Hockessin, Delaware 19707 Contact: 888-448-1203 Southern Maryland Urban Pest Conference November 28, 2012 Location: Baden Fire Hall, Baden, MD Contact: Brian Clark, 301-868-8780 2012 Pest Management Conference December 13, 2012 Location: Carroll Community College, Westminster 7
Advanced Landscape Plant IPM PHC Short Course January 7-10, 2013 For registration information contact: Contact: Avis Koeiman, 301-405-3913 akoeiman@umd.edu MAA Winter Conference January 16 and 17, 2013 Location: Turf Valley, Ellicott City, MD Contact: 410-321-8082 Delaware Horticulture Industry Expo January 23 & 24, 2013 Location: Modern Maturity Center, Dover, DE Contact: 888-448-1203 Green Industry Professional Pesticide Recertification Seminar Janury 24, 2013 Location: Northern Virginia Community College Annandale Campus Contact: Mary Bean, mbeanhouse@aol.com, 202-215-1134, www.greenindustryseminar.org FALCAN Conference January 30, 2013 Location: Frederick County Fairgrounds, Frederick, MD Contact: Dan Felice, 301-606-8631 2013 Mid-Atlantic Horticulture Short Course February 4-7, 2013 Location: Marriott at City Center, Newport News, VA http://www.mahsc.org/ Eastern Shore Conference Pesticide Conference February 13, 2013 Location: The Fountains, Salisbury, MD Contact: Ginny Rosenkranz, 410-749-6141 2013 Chesapeake Green: A Horticulture Symposium February 14 and 15, 2013 Location: Maritime Institute, Linthicum Heights, MD LCA Winter Conference February 14, 2013 Contact: 301-948-0810, http://www.lcamddcva.org/ Maryland Christmas Tree Association Winter Meeting February 23, 2013 Friendly Farms Restaurant, Upperco, MD Contact: Wilma Muir, 410-452-9793 Southern Maryland Landscape Conference March 6, 2013 Location: TBD, in Waldorf, MD Contact: Brian Clark, 301-868-8780 Interstate Ornamental Plant Management Conference April 3, 2013 Location: Maritime Institute, Linthicum Heights, MD Contact: Avis Koeiman, 301-405-3913, akoeiman@umd.edu 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 rosnkrnz@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.