for Arborists, Landscape Managers & Nursery Managers

Commercial Horticulture July 6, 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- Imported willow leaf beetle- Vinca problems- Japanese beetles- Tuliptree aphids- Green June beetles- Redheaded pine sawfly- Clearwing moths

Weed of the WeekPlant of the WeekDegree DaysPhenologyConferences

Integrated Pest Management for

Commercial Horticulture

www.ipmnet.umd.edu

June 29, 2012: Record Temperature Set for JuneThe temperature on June 29, 2012 in Washington D.C. reached 105 °F and in Baltimore it reached 104 °F. This heat breaks a record for June set back in 1935. Note this date because we will likely see plant injury show up in the next couple of weeks from the high temperatures. The high temperatures hung on for several additional days with temperatures in the high 90 °F to low 100 °F range. People were wilting and so were many plants.

The storm that blew in from the West around 10:00 p.m. on June 29th caught most people by surprise and caused more damage than most hurricanes. On the positive side the arborists were put to work in short order and they are probably tired but happy to have the work this week. The damage from the bizarre mini-tornado-like winds hit from the Carolinas up to southern Carroll County, If you have any prized pictures of damage from this storm, send them in and we will publish them next Friday. Send to sgill@umd.edu.

The high temperatures continued through this week and now the weather forecasters are predicting temperatures of 103 °F by Saturday, July 7th. This extremely hot weather will impact plant material that is in a marginal condition with compromised root systems or any newly transplanted plants. There were water bans in many counties with the power outages after the storm which have now been lifted. Be sure to irrigate plants during these stressful weather conditions.

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Imported Willow Leaf BeetleDamian Varga, Scientific Plant Service, found imported willow leaf beetle adults active on corkscrew, weeping and pussy willows last week in Baltimore, Catonsville, and Millersville. Look for small holes caused by the adults and skeletonized damage on foliage caused by the larvae.Control: There are natural enemies present that feed on this beetle. If necessary, labeled synthetic pyrethroids work well on leaf beetles.

Imported willow leaf adults and damagePhoto: David Cappaert, Michigan State University, Bugwood.org

Different larval stages of imported willow leaf beetle

Brian Clark, UME-Prince George’s County, sent us an email pointing out the front page of The Washington Post on Sunday. LaPlata made front page news in both The Washington Post and Maryland Independent. He noted that in his area sycamores seemed to take the brunt of the damage, but he has seen large oaks ripped down and an ornamental pear snapped clean, 6’ off the ground. Brian’s high tunnel (Upper Marlboro) survived with no ill effects.

How is the rest of the country doing with weather?Florida: On June 28, I (Stanton) spoke with Chris Hayes of BioWorks Company, who said that Florida just went through one of Florida’s longest droughts which was abruptly ended with a slow moving storm that flooded much of Florida. On the bright side for Florida he said they are seeing record numbers of vacationers visiting the state since gas is relatively cheap again.Mid- West: I spoke with relatives in Ames, Iowa. Iowa is in the middle of a prolonged drought and the farmers are saying for every week without rain they continue to lose an average value of the corn crop by $10/week. It needs to rain there soon.West: Colorado had one of the least snowy winters in a long time and a relatively dry spring. The landscape has been dry and brown for months. Fires broke out and are scorching the dry landscape.

Vinca ProblemsThe Plant Diagnostic Lab confirmed Phytophthora on a vinca sample brought in with dieback this week. The vinca was growing in the landscape. To reduce the incidence of this disease, avoid planting vinca in the same planting beds year after year. Plant in an area with good drainage or use raised beds. Sanitation is important in minimizing this disease.

Japanese BeetlesThis summer, we continue to receive emails reporting heavier populations of adult Japanese beetles in southern Maryland, central Maryland and the Eastern Shore of Maryland.

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Tuliptree aphids - winged adult (left) and nymph (right)

Redheaded pine sawfly larvae on mugo pinePhoto: Mark Schlossberg, ProLawn Plus

Tuliptree AphidsDamian Varga, Plant Scientific Service, found aphids on tuliptrees (Liriodendron tulipifera) on June 27 in Ellicott City and Glenelg, Here at the research center, the tuliptree aphids (Macrosiphum liriodendri) on the tuliptrees on the edge of the parking lot have been very prolific this year. Honeydew secreted by the aphids is coating cars and plants underneath. Many of the honeydew-coated leaves are dropping early and are sticky to walk on. Tuliptree aphids are light green to pink. Various stages of lady bird beetles are present on the foliage to help control these populations. Parasitic wasps also attack aphids and leave behind a tan, papery ‘mummy’.

Green June BeetlesSteve Sullivan sent an email asking if green June beetles are more common or not this year. I (Stanton) have seen a lot of activity of adult beetles flying around landscapes. The adults feed on decomposing fruit and vegetables but are generally not a plant feeding beetle. If you see a lot of activity in your area let me know at sgill@umd.edu.

Redheaded Pine SawflyMark Schlossberg, ProLawn Plus, Inc., found redheaded pine sawfly larvae feeding on mugo pine on July 6 in Pikesville. Look for larvae with reddish heads and yellowish white body with six rows of irregular black spots. Larvae feed gregariously and strip the needles from the top terminals and branches. This native sawfly has two generations per year in this area. Trees growing on shallow soils, wet or dry sites, or under other stressful conditions are most often attacked.Control: For isolated trees prune out branches where sawflies are aggregated. If numerous trees are infested,treat with Conserve or a synthetic pyrethroid.

Close-up of redheaded pine sawfly larvae

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Hummingbird Clearwing and Snowberry Clearwing MothsAt this time of year, when monarda is in bloom, we see the hummingbird clearwing (Hemaris thysbe) and snowberry clearwing (Hemaris diffinis) moths here at the research center in Ellicott City. So far this year, only the hummingbird clearwing moth has been spotted. These moths, which look a lot like bumblebees, hover like hummingbirds as they nectar on flowers during the day.Control: No control is necessary.

Hummingbird clearwing moth

Weed of the Week, Chuck SchusterCommon cat’s ear, Hypochaeris radicata, often called false dandelion, is a perennial weed being seen currently. Found in many settings, it is a weed in turf, landscapes and in some cases nursery and Christmas tree fields. Plants have a basal rosette. Leaves are hairy and have irregularly lobed margins. Flower stalks are leafless and have between two to seven flowers per stalk. Flower stalks when cut emit a milky sap. The bright yellow ray petals have teeth on the tips. Each flower is one to one and one half inch in diameter. Similar to dandelion, the seed dispersal method is through wind.

Control of common cat’s ear can be achieved in turf settings using many different broadleaf herbicides. 2-4D is a product that is effective. Most three way products provide excellent control. In landscapes, nurseries and Christmas tree production these products can cause damage. Atrazine can be used for pre-emergent control and would be safe in these settings. Post emergent products in the landscape, nursery and Christmas tree setting are limited. Spot spraying of non-selective herbicides will be useful.

Common cat’s earPhoto: Joseph M. DiTomaso, Univ. of California, Davis, Bugwood.org

Plant of the Week, Ginny RosenkranzAcanthus mollis, common bear’s breeches, blooms in the late spring and early summer. The tall flower spikes are filled with alternately arranged purple and white hooded flowers that resemble snapdragons. Flower spikes can grow 3-4 feet tall while the boldly lobed dark green foliage can grow to 2 feet tall and wide. The mound of foliage can grow 3-4 feet tall, creating an interesting background for many flowers. The leaves look like they are very spiny, while in fact they are soft. The roots can become very aggressive and spread in very loose soils so it is very important to plants Acanthus mollis in areas that can be contained. They are winter hardy from

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USDA zone 7-10 and thrive in moist, well drained soils in either full sun or partial shade. Newly transplanted plants may not flower for a year or two, but once established they bloom with many tall flower spikes. Snails and slugs can be occasional visitors.

Degree Days (As of July 5)* 2012 2011 2010Baltimore, MD (BWI) 1897 1804 1887Dulles Airport 1826 1748 1843Frostburg, MD 1168 1015 1112 Martinsburg, WV 1736 1591 1559 National Arboretum 2206 1958 2112 Reagan National 2206 1958 2112 Salisbury 1960 1843 1779

*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

Photos of Acanthus mollis: Ginny Rosenkranz, UME

PLANT PLANT STAGE (Bud with color, First bloom, Full bloom, First leaf)

LOCATION

Saururus cernuus Full bloom (July 2) Ellicott CityVitus agnus-castus Full bloom (July 2) Ellicott City

Plants in Bloom

August 6, 2012 Cut Flower Tour

Sites: M and M Plants, Dickerson, MD and Farmhouse Flowers and Plants, Brookeville, MDTime: 8:30 a.m. to 3:30 p.m.Sponsored by University of Maryland Extension in cooperation with Maryland Greenhouse Growers’ Association and the Association of Specialty Cut Flower Growers

What better thing is there to do in August then to visit other people’s cut flower operations? For the first time M and M Plants will “open their doors” for other cut flower growers to come and see how they produce quality cut stems for their farm markets. M and M Plants is nestled in the foothills of Sugar Loaf Mountain in Upper Montgomery County. M and M Plants uses both field and high tunnel production to produce their cut flowers. Lunch and an indoor talk will be at the Montgomery County Extension office followed by a tour and talk at nearby Farmhouse Flowers and Plants.

For a brochure, go to http://ipmnet.umd.edu/conferences/index.htm

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

PANTS 2012 (Pennsylvania Nursery Trade Show)July 31 to August 2, 2012Location: Greater Philadelphia Expo Center, Oaks, PAwww.pantshow.com/2012

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

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

Mark Your CalendarChesapeake Green 2013A Horticulture Symposium

February 14 and 15, 2013

at the

Maritime Institute, Linthicum Heights, MD

(near BWI)