TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers Commercial Horticulture July 8, 2011 In This Issue... - Don Riddle - Stressed kousa dogwoods - Fletcher scale - Cottony maple scale - European elm scale - Biting insects - Green June beetles - Lace bugs - Imprelis update - Lightning damage - Sawflies - Japanese beetles - Big eyed click beetle 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) Weed 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 A Great One Is Gone Don Riddle, owner of Homestead Gardens, passed away this week at age 63. Don was a wonderful plantsman who started and ran a very progressive garden center, Homestead Gardens of Davidsonville. He was a dedicated nurseryman who served on the MNLA board and many advisory boards for the green industry. His leadership in the horticultural industry will be greatly missed. We cannot say enough good things about this guy and this will have to serve as a special salute to a friend, colleague and great person. Dry Weather and Cornus kousa We received a call this week inquiring why Cornus kousa trees are showing dieback and scorching, mainly of the upper canopy of the tree. The Chinese dogwood is often planted in full sun which works in several seasons, but when we have a really hot summer like last year and this season the tip growth will show scorch and some dieback. Trees planted in better soils, with abundant water and partial shade seem to fare better.
Fletcher Scale Fletcher scale, commonly found on evergreens, is in the crawler stage in central Maryland this week. Control: This scale species can be controlled with foliar applications of Distance or Talus. Another control is to apply TriStar or Safari as either a foliar application or a soil drench. Fletcher scale with crawlers Cottony Maple Scale We started seeing egg hatch of cottony maple scale this week in the Frederick area. Preferred hosts of this native scale include elm, maple, hawthorn, dogwood, sycamore, poplar, linden, and grapes. There is one generation per year. Control: Same control methods as mentioned under Fletcher scale. Cottony maple scale Photo: Eugene E. Nelson, Bugwood.org European Elm Scale Dave Freeman, Oaktree Property Care, sent in a photo of European elm scale that he found this week. Crawlers can be found throughout the summer. Control: Soil drench of dinotefuran (Safari) or imidacloprid (Merit in landscape, Marathon in the nursery). European elm scale Photo: Dave Freeman, Oaktree Property Care Biting Midges, Gnats and No See Ums This Fourth of July weekend was perfect for outdoor activities. Because people were out in grassy areas this weekend the number of emails and calls from landscape managers about biting gnats, midges and No See Ums rocketed. Here is the lowdown on these pests of summer: How Many Types of Biting Midges Are There? Biting midges are flies (in the Order Diptera) in the family Ceratopogonidae, with over 600 species in 36 genera that have been described in North America. The good news is that the vast majority of these annoying insects feed on other insects or other non-human animals. Species in only four genera of biting midges feed on the blood of mammals. The genera of greatest importance to human and livestock health in the U. S. are Culicoides, Leptoconops, and Forcipomyia. They are annoying but no health risk is associated with them except from your customers swatting at them and maybe hitting themselves in the head. The bites of biting midges cause a burning sensation. Reactions in humans vary and can range from a small reddish welt at the bite site to local allergic reactions that cause significant itching. 2
What Can You Do? Party inside and stay off the lawn area. Yes, I know this is not going to happen for most people. These pests are only out for July and mid-way in August for most years. Spraying with an insecticide will do very little good. Some people use citronella candles in activity areas to drive the gnats out. Wearing a broad rim hat is very fashionable in 2011 and will help keep the gnats out of the person s face. You can buy the goofy-looking but effective hats that have pull down netting that covers your face and neck. Using insect repellents containing Deet is also an option. Green June Beetles Green June beetles are active this week in Brookeville. Adults often hover over landscape beds and lawns that have a lot of thatch. Green June beetles are more of a pest in soils where there is a lot of organic material which is their primary food source. In golf turf, if there is a high infestation they may cause damage because of the burrowing / holes and soil piles they leave. Monitoring: If you have trees with wounds, you might find green June beetles feeding on the sap. At this time, adults are hovering over grassy areas looking for mates. Control: Green June beetles are usually not a pest on trees, but sometimes they can be found feeding on ornamental plants such as the Rose of Sharon or on fruit. These beetles are more of a problem in turf. If grub control is warranted in turfgrass many of the neonicotinoids are labeled and give good control such as imidacloprid, clothianidin, and thiamethoxam. A somewhat newer product that has shown excellent control of grubs is Acelepryn. Sycamore Lace Bugs and Azalea Lace Bugs Nymphs and adults of sycamore lace bug are present on sycamores in Ellicott City this week. Dave Freeman, Oatktree Property Care, is finding azalea lace bugs on azaleas this week. Monitor sycamores, London plane trees and azaleas for stippling on the foliage. Eggs and nymphs can be easily seen on the undersides of the foliage. Lace bugs suck chlorophyll from leaves, starting along the major veins. Heavy feeding can cause premature leaf drop. Lace bugs also leave black fecal spots on the undersides of the foliage. Both lace bug species have four generations in Maryland so multiple stages can be found throughout the summer. Control: For large trees there really are not many practical controls at this time of year. Smaller trees and shrubs can be treated with foliar applications of TriStar or Merit. It would be best to wait until next spring and inject the soil with Merit for season long control. 3 Sycamore lace bugs: adults and fecal spots (left) and various stages of nymphs (right) Imperlis Update You can view a letter from DuPont related to the recent problems with Imprelis that was sent out to turf management professionals on their website at http://www2.dupont.com/professional_products/en_us/assets/downloads/pdfs/letter_to_imprelis_customers_061711.pdf
The photos above show lightning damage from a recent storm Photos: David Clement, Home and Garden Information Center Sawflies Bill Miller, The Azalea Works, sent in photos of sawfly larvae feeding on Harry Lauder s walking stick (Corylus avellana Contorta. Dave Freeman sent in a photo of the bristly rose sawfly this week. Control: Spinosad (Conserve) can be used for control. Bristly rose sawfly Photo: Dave Freeman, Oaktree Property Care Early instar sawfly larvae feeding on Harry Lauder s walking stick Photo: Bill Miller, The Azalea Works Japanese Beetles Connie Bowers, Garden Makeover Company, is reporting that Japanese beetles have been active for a few weeks in Colesville. They have been feeding on Knockout roses and Harry Lauder s walking stick. Karen Bernstein, Arbormasters, Inc., has been seeing them for the last two weeks in Baltimore County. Japanese beetles were also found feeding on zinnias in Brookeville and on wild grapes and rose foliage in Ellicott City and sassafras in Columbia. Japanese beetles feeding on roses Photo: Connie Bowers, Garden Makeover Company 4
Big Eyed Click Beetle (Alaus oculatus) The larvae of these beetles are predaceous and feed on wood boring larvae. Look for theses beetles under logs and in other damp places. The adults feed very little, if at all. Weed of the Week, Chuck Schuster Mulberry weed or hairy crabweed (Fatoua villosa), is a summer annual found throughout the southeastern United States. Named because it is similar to mulberry trees when the weed is less than five inches tall and has less than six leaves. Mulberry weed has prominent hairs on the stems and leaves. The leaves are alternate, toothed, indented with prominent veins, a yellow green color and hairy with a basic triangular shape. Leaves are attached to the stem by a medium length petiole. Stems will secrete a milky sap when cut and the plant has an oily odor. Flowers are produced quickly on this plant, often on the very young plant, and are tan in color. Seed clusters are pea-sized and have the ability to discharge the seed up to four feet from the plant. This weed produces large numbers of seed so good control from germination on is important. Mulberry weed seeds require sunlight to germinate. Mulberry weed can Paw paw fruit and overall view of tree Photos: Ginny Rosenkranz, UME 5 Mulberry weed Mark Czarnota, University of Georgia, Bugwood.org grow to a height of four feet. The plant prefers moist, shaded areas in the landscape or nursery, easily moving from pot to pot in container nurseries. Seeds can remain viable in the soil or under mulch for several years. Mulberry weed can geminate in a wide range of temperatures, from 60 to 90 F. Do not compost this weed unless you can determine if the process gets hot enough to really kill weed seeds. Cultural control can include mulching landscape areas and container plants. Hand removal will work but must start early, as they will produce seed on plants less than three inches in height. Pre-emergent herbicides that have been effective include oryzalin (Surflan) and isoxaben (Gallery). Post-emergent application of either contact or translocated herbicides is also effective, but once the seed is formed will not prevent seed dispersal. Be cautious with the use of glyphosate products in the nursery or landscape where shallow roots or suckers are exposed. Avoid any potential contact with desired species. Plant of the Week, Ginny Rosenkranz Paw paw (Asimina triloba) is a native deciduous tree that is prized for its fruit which is the largest edible fruit native to North America. Growing from 12 to 20 feet tall, it can be prone to root suckers creating a paw paw patch. The leaves are about 6-12 inches long, dark green with an entire margin, and droop slightly on the branch. Fall foliage color occurs in mid autumn and is a Bigeyed click beetle Photo: Dave Freeman, Oaktree Property Care
medium yellow. The flowers are purple, about 2 inches across and last about 6 weeks. The fruit can be between 5 to 16 ounces and ranges from 3-6 inches long. There are 2 rows of brown/black seeds that are shaped like lima beans. Harvest is usually between August through October. Plants need fertile soil that is moist, well drained that is slightly acidic. Paw paw is a food source for the zebra swallowtail caterpillar. The oak root fungus (Armillaria) is a disease that can be a problem. PLANT PLANT STAGE (Bud with color, First bloom, Full LOCATION bloom, First leaf) Asclepias incarnata Full bloom (July 2 Columbia Monarda didyma Full bloom (July 2) Ellicott City Vitus aganus-castis First bloom (July 5) Ellicott City Degree Days (As of July 7) Baltimore, MD (BWI) 1838 Dulles Airport 1770 Frostburg, MD 1078 Martinsburg, WV 1596 National Arboretum 1994 Reagan National 2017 Salisbury 1940 PGMS DC Branch: Thursday, August 4, 2011 Space is limited to 125 people and an RSVP is Required. Directions and more details will follow in the August newsletter. Meeting Location: Bartlett Tree Experts, 1 Metropolitan Ct, Gaithersburg, MD Dinner and tour of Bartlett Tree Experts new facility: 6:00 PM until 7:00 PM. Business Meeting: 8:30 PM until 9:30 PM Lecture: 7:00 PM until 8:30 PM: Tree planting: Planting space design, nursery production and tree purchasing, installation and initial maintenance. Presentation will be approximately 1.5 hours and will begin promptly at 7:00 PM. James Urban, FASLA will have copies of his book Up By Roots: Healthy Trees and Soils in the Built Environment for sale after the lecture. James Urban, FASLA specializes in the design of trees and soils in urban spaces. He has written and lectured extensively on the subject of urban tree planting and has been responsible for the introduction of many innovations including most of the current standards relating to urban tree plantings. His 2008 book Up By Roots: Healthy Trees and Soils in the Built Environment, is becoming one of the principle tree and soil references. James Urban was instrumental in the development of structural cells and structural planting soils for use under sidewalk pavements, and is credited with helping to re-awaken the profession of landscape architecture to the skills required to successfully plant trees in difficult urban soils. In 2007 he was awarded the ASLA Medal of Excellence for this contribution the profession of Landscape Architecture. RSVPs are on a first come first serve with a maximum of (125) attendees Please RSVP by July 27 with your name and contact information, whether you are a member or not and the number of guests to: Adam Newhart, City of Gaithersburg-DPW, (O) 301-258-6370 ext. 103, (F) 301-258-6375, anewhart@gaithersburgmd.gov 6
Upcoming Programs: July 21, 2011 PGMS Field Day and Trade Show Location: American University, Washington, D.C. Contact: 703-250-1368 August 1, 2011 Cut Flower Tour in Southern Maryland Locations: Mechanicsville and Loveville, MD Contact: 301-596-9413 August 4, 2011 PGMS DC August Branch Meeting Location: Bartlett Tree Experts, 1 Metropolitan Ct, Gaithersburg, MD Contact: Adam Newhart, City of Gaithersburg, (O) 301-258-6370 ext. 103, anewhart@gaithersburgmd.gov 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 and FALCAN for your financial support in making these weekly reports possible. 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.