for Arborists, Landscape Managers & Nursery Managers

Commercial Horticulture October 23, 2015Coordinator 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 AssistantDisease 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)

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- Egg masses in the landscape- Unusual bloom time- Montgomery County Pesticide Ban

Beneficial of the WeekWeed of the WeekPlant of the WeekDegree DaysAnnouncements

IPMnetIntegrated Pest Management for

Commercial Horticulture

extension.umd.edu/ipm

Cold Has ComeBy: Stanton Gill, University of Maryland ExtensionThe cold winds blew in freezing temperatures on October 17 and 18 and killed most of the annuals in the landscape. The fall color should become very strong in the coming week with the cool night temperatures. Something to keep in mind is that white pines commonly show fall color with the older needles turning yellow and then brown at this time of year. Every year we get people asking why the white pines are dying in October and November when it is merely fall color of the old needles.

On the good side, the cold weather has stimulated people to install fall violas, pansies, mums, and ornamental cabbages to put color back in the landscape. This fall landscaping is good for the greenhouse industry in the state.

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Look for Carolina praying mantid (left) egg masses and Chinese praying (right) mantid egg masses in Maryland

Mantids and Assassin BugsBy: Stanton Gill, University of Maryland ExtensionWe are receiving reports of mantid egg masses being laid on plant material in the landscape. The cold weather stimulates the female mantids to lay their egg masses before they die. The other egg masses being found are of assassin bugs which are laid on smooth barked stress such as birch and maples. The egg masses should be left on the trees so these beneficial can hatch out this next spring to feed on insects in the nursery and landscape. Keep an eye out for eastern tent caterpillar egg masses and prune them out when possible.

Small red and black assassin bugs hatched from these barrel-shaped eggs in the spring

Here is an egg mass that you want to prune out whenever possible; eastern tent caterpillars will hatch from these eggs

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Beneficial of the WeekBy: Paula Shrewsbury, University of Maryland

We are getting close to Halloween so let’s talk mummies

“Mummies” are not just bodies that have been wrapped and preserved over hundreds and thousands of years that we tend think about around Halloween. “Mummies” are also the stage or phenomena referred to for the response of aphids and other insects after attack by parasitic wasps. Over the season there have been numerous reports of aphids on various plant species. The nice thing about aphid infestations is that in many situations chemical controls are not needed because there is a suite of natural enemies that ultimately reduce, and often eliminate, aphid populations. The aphid natural enemy complex includes various species of lady beetles, predatory flies such as syrphid (flower) flies and Aphidoletes midges, lace wing predators, and parasitic wasps. Today I would like to discuss the parasitic wasps since I have recently observed aphid populations, usually at pretty low levels, that have been attacked by these parasitoids and Dr. Karen Rane received a sample this week in the Diagnostic Lab (UME) that had aphids, or should I say aphid mummies - almost every aphid had been mummified! The tell-tale sign

Tan aphid mummy image – Rose aphid mummy with a parasitic wasp in the genera Aphidius developing within itPhoto: M. Raupp, University of Maryland

Unusual Bloom TimeBrian Scheck, Maxalea, Inc., found cherry laurel blooming out of season. Brian photographed shrubs blooming on October 21.

Pesticide Use Ban in Montgomery CountyInformation on the Montgomery County Pesticide Ban is covered in an article written by Charles Taylor for County News, the on-line newsletter of the National Association of Counties, at http://www.naco.org/articles/pesky-penalties

This group of cherry laurels is a bit out of season by blooming nowPhoto: Brian Scheck, Maxalea, Inc.

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of wasps killing aphids is the presence of aphid mummies. The wasps themselves are less than 1/8” in length. Female wasps, many in the genera Aphidius (Family: Braconidae) insert their ovipositor into the body of an aphid and deposit a single egg. Oviposition involves the wasp adult whipping her abdomen under her body and quickly “stabbing” the aphid, ultimately inserting the egg. The egg hatches and the wasp larva feed on the insides of the aphid. During this process the aphid’s body becomes swollen or bloated looking, and the exoskeleton turns from its natural color to tan and has the look of a papery shell – hence the name aphid mummy (see images). Not surprisingly this results in the death of the aphid. As the wasp larva completes its development it pupates within the aphid. When the adult is formed it chews a discrete circular hole (see image) in the exoskeleton of the aphid and emerges from the mummy. At this point the female wasps can move on to parasitize other aphids. Each female wasp can kill up to hundreds of aphids in its lifetime. In addition to these tan aphid mummies there is another genera of parasitic wasp, Aphelinus, which similarly attacks and ultimately kills aphids. However, the bloated bodies of Aphelinus parasitized aphids turn shiny black in color rather than tan. So as you are out scouting your plants and getting ready for winter, be sure to look for those aphid mummies! They can have a tremendous impact in reducing aphid populations.

Go to the following YouTube link to see a great video of aphids and wasps interacting… the aphid ultimately loses (oops – I told you the ending to the movie).https://www.youtube.com/watch?v=rLtUk-W5Gpk&index=7&list=PLEyJWYOhCCOaqSqa789_7rzfNNdF-YZWz

A healthy oleander aphid (orange color) colony showing black aphid mummies which were parasitized by a wasp in the genera AphelinusPhoto: M. Raupp, UMD

Rose aphid mummy showing the circular exit hole formed when the adult parasitic wasp emergesPhoto: M. Raupp, UMD

Weed of the WeekBy: Chuck Schuster, University of Maryland Extension

Weed control is an ever challenging part of turf and landscape management. Proper plant identification and understanding the cultural characteristics of a particular site are several of the many different things to consider when managing specific settings. As pesticide options are reviewed more and more in governmental forums, making sure all options are considered is extremely important.

Nutrient management is part of good weed management. Proper pH management as well as proper nutrient applications can help manage weeds and promote the desired species of plant material. Proper pH can stress the weeds and help the pre-emergent products work more efficiently. In turf, good dense stands are one leg of the three-legged stool for a high quality turf.

Mowing management, proper height, sharp blades and proper timing also help. During the spring, mowing more than once a week helps prevent excess thatch and keeps weeds from reaching the reproductive seed stage. In landscapes, the mulch barrier is an important tool as well. Using a weed fabric is part of some management plans. Placement of pre-emergent products is another aspect of weed control in landscape. Type and size of mulch, bark versus double and triple ground mulch need to be considered as one determines the product and placement of these products in the landscape.

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Pinus flexilis ‘Vanderwolf’s Pyramid’ makes a lovely specimen tree for smaller spacesPhotos: Ginny Rosenkranz, UME

Plant of the WeekBy: Ginny Rosenkranz, University of Maryland Extension

Pinus flexilis ’Vanderwolf’s Pyramid’ or the limber pine is native to the Rocky Mountains. Growing only 20-30 feet tall and 10-15 feet wide, this lovely pine has 2 ½- 3 ½ inch long twisted soft silvery blue green needles. The stems are tough and flexible, and according to Dr. Dirr, can be tied in a knot. The tree itself grows very slowly to form a very structured pyramidal shape. It grows best in moist well drained soils and needs full sun, does well in hot, dry summers and wet winters. Cold tolerant from USDA 4-7, it is resistant to deer browsing as are most pines. The evergreen needles and the pyramid silhouette lend it to 4 seasons of interest in the landscape as a lovely specimen tree for smaller spaces.

Pinus flexilis ’Vanderwolf’s Pyramid’ is susceptible to white pine blister rust, so should never be planted near currants or gooseberries as they are the alternative rust host. It is also susceptible to aphids weevils, spider mites and scale.

Degree Days (As of October 22) 2015 2014 2013 2015 2014 2013Baltimore, MD (BWI) 3961 3634 3844 Dulles Airport 3895 3438 3818Frostburg, MD 2708 2259 2350 Martinsburg, WV 3630 3452 3497 National Arboretum 4778 4501 4442 Reagan National 4778 4501 4442Salisbury 3934 4075 4254 St. Mary’s City 4095 3846 3994

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.

Overall IPM is very important even with the “simple” problematic plants dealt with. Consider all options in planning for the control of those plants whose economic value has yet to be determined. There is no one option that solves all weed control issues. Plan now for spring, review soil tests for pH and adjust as needed. Monitor soil temperature in the spring as you plan for pre emergent products in the turf. All of this methods will help provide the results that are desired.

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Biocontrols School in PennsylvaniaNovember 5 and 6, 2015Lancaster Farm and Home Center1383 Arcadia Road, Lancaster, PA 17601For more information

December Pest Management ConferenceDecember 10, 2015Location: Carroll Community CollegeContact:sklick@umd.edu

Nutrient Management Recertfication for Turf ProgramDecember 11, 2015 (half day)Location: Carroll Community CollegeContact:sklick@umd.edu

MANTSJanuary 6 – 8, 2016Location: Baltimore Convention Center, Baltimore, MDFor information: http://mants.com/

Advanced Landscape Plant IPM PHC Short CourseJanuary 4-7, 2016For registration information contact: Avis Koeiman, University of MarylandDepartment of Entomology, 4291 Fieldhouse Dr., College Park, MD 20742301-405-3913, akoeiman@umd.edu

PGMS Green Industry SeminarJanuary 22, 2016Location: NOVA Community College

FALCAN ConferenceJanuary 21, 2016Location: Frederick County Fairgrounds, Frederick, MDContact: http://www.falcanmd.com/

Maryland Arborist Association ConferenceJanuary 27 and 28, 2016Location: Turf Valley, Ellicott City, MDContact: http://www.mdarborist.com/

Eastern Shore Pest Management ConferenceFebruary 3, 2016Location: The Fountains, Salisbury, MDContact: Ginny Rosenkranz, 410-749-6141http://www.eventbrite.com/d/md/eastern-shore-pest/

LCA Pesticide and Fertilizer Applicator ConferenceFebruary 11, 2016 Location: University of Maryland Shady GroveContact: 301-948-0810

Chesapeake Green 2016: A Horticulture SymposiumFebruary 18 and 29, 2016Location: Maritime Institute, Linthicum, MDContact: 410-823-8684

Greenhouse ConferenceMarch 2, 2016 Location: Chesapeake College, Wye Mills, MD

Invasive SpeciesApril 7, 2016Location: TBD

2015-2016 Commercial Horticulture Conferences

Conferences are listed at http://extension.umd.edu/ipm/conferences

Schedules, registration information and links are included when available

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.

Stanton GillExtension Specialist

sgill@umd.edu410-868-9400 (cell)

Paula Shrewsbury Extension Specialistpshrewsb@umd.edu

Ginny RosenkranzExtension Educatorrosnkrnz@umd.edu

Chuck SchusterExtension Educator

cfs@umd.edu

Karen Rane Plant Pathologistrane@umd.edu

Andrew RistveyExtension Specialistaristvey@umd.edu

David ClementPlant Pathologist

clement@umd.edu

Nancy HardingFaculty Research

Assistant