for Arborists, Landscape Managers & Nursery Managers

Commercial Horticulture September 7, 2012Coordinator 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)

In This Issue...

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

TPM/IPM Weekly Report

- Weather update- Weed control- Indian wax scale- Brown marmorated stink bugs- Black bear activity - Snowy tree crickets- Woolly beech aphid- Aronia update- Caterpillars on oak- Powdery mildew- Sooty blotch and fly speck on apple

Beneficial of the WeekWeed of the WeekPlant of the WeekDegree DaysConferences

IPM Pest WalkSalisbury, MD

September 6, 2012.5 ISA credits

Contact:Ginny Rosenkranz

410-749-6141

RainRecent rainstorms are finally getting some moisture into the ground. With the rain comes an increase of leaf spotting diseases showing up on different plants. Ornamental and sweet cherries have leaf spots and heavy defoliation. Walnut foliage is also showing heavy leaf spotting and early defoliation. Many nursery owners are reporting that weeds have taken off with the rains. It is sometimes hard to stay ahead of the weeds, but now is the time to get fall pre-emergent herbicides applied to prevent germination of fall weeds.

Weed Control and Automation: Two weeks ago several Maryland nursery owners and I travelled to Holland and Germany to visit progressive nurseries. In The Netherlands they are planning on severely restricting the use of herbicides in nurseries in the very near future. They have developed several mechanized machines to help control young weeds around plants. They appear to work well on young weeds, but this means you have to cultivate around the plants fairly often in the season. Also, if you get an extended rainy period and the weeds get ahead of you it will be very challenging to control the weeds without use of herbicides.

Photo: Jerry Faulring, Waverly Farm

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Indian Wax ScaleKelly Wilson, Arlington National Cemetery, is finding a lot of Indian wax scale on Ilex glabra, cherry laurels and boxwood. A site manager even found them on an Amsonia. She noted that this infestation is the worst that she has ever seen. This scale has a wide host range which includes holly, hemlock, camellia, barberry, nandina and pyracantha. This scale looks like a blob of white wax. If you pop off the cover, you will find the red to pinkish body of the scale underneath. The crawlers were active in July. Control: Soil injection of imidacloprid (Merit) or Dinoterfuron (Safari, Transtect)

Brown Marmorated Stink Bugs (BMSB)We continue to receive reports from many of the readers of this IPM Alert letting us know that they are finding brown marmorated stink bugs feeding in their vegetable gardens on tomatoes, peppers and fall ripening raspberries such as ‘Caroline’. Jeanette Tansey is reporting a marked increase of stink bugs over the past week in Catonsville adjacent to Patapsco State Park. Adria Bordas, Virginia Cooperative Extension, has noticed increased activity of BMSB on tomatoes in Fairfax County. Preston Leyshon, Chapel Valley Landscaping, is reporting that at a vegetable garden in Winfield - Taylorsville their first crop of corn was great, but about 3 weeks later in mid August, when the second planting was getting close to harvest time, the stinks bugs beat them to it. Preston noted that about two weeks ago the stink bugs attacked two long rows of tomatoes that were producing all summer, but now about 95% of have been destroyed and ruined.

Snowy tree cricket and damage

Black Bear ActivityBlack bear seem to be making a comeback in central Maryland. In the spring of 2012, a bee keeper in Montgomery County had several hives overturned by black bears. DNR helped them in funding the installation of fencing around their bee hives. Now, in upper Carroll County there have been sightings of black bears wandering around in the last week. If you can confirm black bear activity in your area send me (Stanton) an e-mail at sgill@umd.edu and we will put an update in future IPM Alerts

Snowy Tree CricketsWe are getting reports with increasing frequency this week of cherry laurel and rhododendron with upper leaf surface chewing damage from snowy tree crickets. Tree crickets skeletonize the upper surface of cherry laurel, azalea, and rhododendron foliage in August through early October. They feed at night and are rarely found during the day. Unless the tree crickets are significantly damaging the plant, control is not necessary.

Indian wax scale; photo on right shows red body underneath cover.

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Datana contracta caterpillarsPhoto: Todd Armstrong, Davey Tree Experts

Aronia fruitPhoto: Andrew Ristvey, UME

Photo: Rasma Plato, John Shorb Landscaping

Woolly Beech AphidRasma Plato, John Shorb Landscaping, found woolly beech aphids on a single branch of a beech tree in Bethesda and Melissa Stevens, Potomac Watershed Forester, found them in Garrett County. She noted that there were several trees in the area with entire branches infested. Control: This aphid is very noticeable at this time of year, but it usually does not cause enough plant damage to warrant control measures. Photo: Melissa Steves, Potomac

Watershed Forester

Aronia UpdateAronia harvest time is now if you have not done so already. While this past summer was quite stressful on a lot of plants, your Aronia should have fared OK, especially if you were able to irrigate occasionally. If you have not already harvested be sure to check you fruit. Try to harvest before they start to wrinkle. Fall preparation for Aronia plants consists of trimming out dead material. Save the major pruning for spring.

For fall fertilization, go with a light nitrogen rate of no more than ¼ oz of N per plant in late October or November. Adjust your phosphorus and potassium based on your nutrient management plan and your soils tests. I hope you had a good harvest.

There will be an Aronia Twilight Tour, September 19 from 3 to 7 PM at Fair Spring Nursery, Marydel, MD, hosted by Gerry Godfrey, the Mid-Atlantic Aronia Growers Association (MAGA), and University of Maryland Extension. There you will learn about organic farm certification, the latest in Aronia research and about what MAGA can do for you as an Aronia grower. Mr. Godfrey will show you around Fair Spring Nursery and we will have a cook-out with burgers and hotdogs. Come and enjoy the afternoon while learning about Aronia. The event is free, but please register with Debby Dant at 410-827-8056. To learn more about the program and agenda please visit www.aronia4md.umd.edu.

Caterpillars on OakTodd Armstrong, The Davey Tree Expert Company, found caterpillars feeding on red oak on August 31 in the Park Heights area. The caterpillar is Datana contracta which is in the same genus as the yellownecked caterpillar. He noted that the feeding damage was fairly minor so he simply clipped the branch on which the caterpillars were congregating.

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Powdery mildew on red twig dogwoodPhoto: Mark Schlossberg, ProLawn Plus, Inc.

Powdery MildewMark Schlossberg, ProLawn Plus, Inc., is reporting powdery mildew on red twig dogwood in Sparks this week. As we start to have more sunny days and cool nights as we move toward fall, expect to see powdery mildew on a variety of plants.

Diseases on ApplesIf any of your customers have apples, then look for the development of sooty blotch and fly speck from the recent rains. These diseases make the apples look bad, but rarely affect the quality of the fruit. The fungi can be removed by washing, rubbing or peeling the fruit.Control: If a treatment is determined to be necessary, then apply Captan at this time.

Sooty blotch and fly speck on apple

Beneficial of the Week, Paula ShrewsburyHunters of CricketsI am referring to the beautiful metallic blue-black wasps known as cricket hunters, Chlorion aerarium. They belong to a family of wasps referred to as thread-waisted wasps (Family Sphecidae) because they have a constriction at the upper end of their abdomen. Cricket hunters occur throughout the United States, southern Canada, and into Mexico. They are about 1.5” long and have several color forms over their range. The cricket hunters I have seen in my yard have bluish wings often held flat over their black body, big eyes, long spiny legs that assist in digging, and rather large pointed mandibles used for holding on to their prey. Oh – and the females have stingers. As adults these wasps feed on nectar resources from flowering plants and are important pollinators. They are commonly found feeding on short toothed mountain mint (Pycnanthemum muticum) and threadleaf milkweed (Asclepias verticillata) in addition to other flowers. The larvae live in the ground, are carnivores and feed on what else – crickets. Adult wasps are frequently seen actively foraging on the ground of fields, meadows, lawns, and garden beds for crickets. Cricket hunters are solitary hunting wasps and have a very interesting biology. A female adult will make a burrow in the ground that consists of multiple egg chambers. The female will catch prey, usually crickets and sometimes grasshoppers or katydids, that she uses to provision the egg chambers with food for her babies. The female hunts, catches, stings, and paralyzes her prey but doesn’t kill it – providing live food for her young.

This cricket wasp has just captured a cricket and is holding it under her body. Note the brown legs and body of the cricket sticking out. Photo: P. M. Shrewsbury, UMD

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The cricket wasp is approaching the entrance to her burrow where she will bring her live but paralyzed prey to provide food for her young. Photo: P. M. Shrewsbury, UMD

Red sorrelPhoto: Virginia Tech Weed Guide

When she brings the prey to the tunnel, she first drops it at the entrance, goes inside, and inspects the tunnel. The hypothesis is that she enters the tunnel “hands-free” so that she is free to defend her home against potential intruders. Once she determines it is safe, she reemerges and drags her prey to an egg chamber. Each egg chamber requires several prey items. When a chamber is adequately provisioned, she lays an egg on the underside of the thorax of one of her victims and closes the chamber, and eventually, the whole tunnel by filling it with soil. After an egg hatches, the larva spends about 10 days feeding and then pupates in the tunnel where it remains through the winter. The adult males are territorial and like to hang out near a good nesting area. There major functions are to eat and mate. Males spend most of their time in the air, chasing off other males and trying to hook up with females. Sperm is the only contribution males make towards reproduction. There is also another family of wasps, Pomipilidae, that similarly hunt spiders.

For more information on cricket wasps go to:http://www4.uwm.edu/fieldstation/naturalhistory/bugoftheweek/great-black-wasp.cfm

Weed of the Week, Chuck SchusterRed sorrel, Rumex acetosella, sometimes called sheep sorrel, is a perennial weed found throughout the United States in many lawn, landscape and nursery settings. Red sorrel reproduces by rhizomes and seed. The root itself is a taproot, but it will have an extensive shallow rhizome. Stems will grow to eighteen inches in total height; are upright and slender, and branch near the top. Several stems arise from the crown. Young leaves are more egg-shaped, and the later leaves are arrow-shaped. The arrow-shaped leaves have two lobes occurring near the base and will most often arise from the rosette. Some leaves will occur on the upright stems. Leaves on the upright stems are alternate, up to three inches in length, and do not have hairs. Flowering stems are ridged and will often have a maroon color. Female flowers are maroon, and male flowers are a greenish yellow in color. Seeds are three-sided, reddish brown in color and shiny. Male and female flowers occur on different plants.

Control of this weed can be achieved using pre emergent products that include isoxaben (Gallery) trifluran (Treflan) abd oxyfluorfen (Goal) both pre and early post emergent and post emergent products that include dichlobenil (casoron) and glyphosate(roundup).

Plant of the Week, Ginny RosenkranzDeciduous magnolias offer so much in the spring and summer that many landscape contractors forget that they sometimes have good fall color as well. Magnolia x ‘Royal Crown’ is a saucer magnolia with large flowers that bloom before the foliage appears. The 10-inch fragrant flowers have petals which are dark rose pink on the outside and creamy white to light pink on the inside and are held upright, resembling a crown. Some early flowers may be killed by late frost, but ‘Royal Crown’ blooms late into early summer so many of the flowers will escape the frost. The flowers mature into irregularly shaped bright red fruit that lasts through part of the winter. The fall foliage is a bright yellow. Magnolia x ‘Royal Crown’ is upright to vase-shaped, growing 15-20 feet wide and 20-25 feet tall. The plants are cold tolerant in USDA zones 5-9 and prefer full sun to partial

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Magnolia x ‘Royal Crown’Photo: Ginny Rosenkranz, UME

Degree Days (As of September 6)*Baltimore, MD (BWI) 3700 Dulles Airport 3595 Frostburg, MD 2371 Martinsburg, WV 3352 National Arboretum 4172 Reagan National 4172 Salisbury 3820

*As of May 11, degree day calculations are from weather.com growing degree day calculations instead of NOAA min and max tem-peratures. To check degree day (DD) accumulations in your local area go to: http://www.weather.com/outdoors/agriculture/growing-degree-days/USMD0100

shade. Soil should be moist but well drained and slightly acidic to neutral. Sapsuckers can create horizontal rows of tiny holes, while scale will infest both the twigs and leaves. Diseases include leaf spots, scab, mildew, and verticillium.

Announcement From DuPont CompanyI (Stanton) received the following email from Bruce Steward, DuPont Company, last Friday: As you may have heard, DuPont Professional Products was divested to Syngenta, which includes the turf and ornamental insecticide products Acelepryn, Provaunt, and Advion. This divestiture agreement is expected to be closed in the next month.

Stanton GillExtension Specialist

sgill@umd.edu

Paula Shrewsbury Extension Specialistpshrewsb@umd.edu

Ginny RosenkranzExtension Educatorrosnkrnz@umd.edu

Chuck SchusterExtension Educator

cfs@umd.edu

Karen Rane Plant Pathologistrane@umd.edu

Brian Clark Extension Educator bpclark@umd.edu

Andrew RistveyExtension Specialistaristvey@umd.edu

David ClementPlant Pathologist

hgic.umd.edu

The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by University of Maryland Extension is implied.

CONTRIBUTORS:

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.

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.

Upcoming Programs

OFA Perennial Production ConferenceSeptember 10 - 12, 2012Location: Grand Rapids, Michiganofa.org

IPPS Eastern Region Annual MeetingOctober 10 - 13, 2012Location: Brandywine Valley, Pennsylvaniahttp://www.ippseastern.com

LCA - Practical Diagnostic Techniques for Landscape ManagersOctober 17, 2012Location: Kenwood Country Club, Bethesda, MD301-948-0810

2012 Pest Management ConferenceDecember 13, 2012Location: Carroll Community College, Westminster MD

MAA Winter ConferenceJanuary 16 and 17, 2013Location: Turf Valley, Ellicott City, MDContact: 410-321-8082

FALCAN ConferenceJanuary 30, 2013Location: Frederick County Fairgrounds, Frederick, MDContact: Dan Felice, 301-606-8631

2013 Chesapeake Green: A Horticulture SymposiumFebruary 14 and 15, 2013Location: Maritime Institute, Linthicum Heights, MD

LCA Winter ConferenceFebruary 14, 2013301-948-0810