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Ornamental Crops IPM E-newsletter, 2007

For Fall 2007

In this Issue:

  1. Bandedwing Whitefly
  2. Hunter Fly
  3. Bio Control Tour Review
  4. New Floriculture Faculty - Neil Mattson
  5. Christmas Tree Growers Workshop
  6. New York Green Industry Conference November 13-15
Cornell IPM Team for Production Ornamentals

Bandedwing Whitefly-Don’t Count on this One

Brian Eshenaur, NYS IPM
Elise A. Schillo- Lobdell, The Plant Keeper
John Sanderson,  Entomology Dept. Cornell University
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At first glance Bandedwinged whitefly, Trialeurodes abutiloneus, looks just like greenhouse or silverleaf whitefly They are all snowy white, flit around on greenhouse plants and can be found on sticky cards. But a closer look reveals gray stripes or wing bands on the banded wing whitefly. It is not unusual to find the banded wing whiteflies in greenhouses and on sticky traps. Outdoors they can be found on soybeans and other plants. They may migrate into greenhouses and show up on poinsettia and other plants such as petunia, geranium and hibiscus. Since they are not known to reproduce on greenhouse poinsettias, their presence can be ignored and they should not be included in counts used to determine thresholds for treatment.

However, the biological world being what it is… we know that insects sometimes change. So you may want to keep an eye out for nymphs of banded-wing whitefly on the leaves of your greenhouse crops. The nymphs look very much like those of the greenhouse whitefly but have varying dark brown spots or a blotch visible on their backs. If you see something suspicious contact your local Extension personnel and they can help you get the sample to a lab where it can be identified.

Hunter Fly: Open season on Fungus Gnats

Betsy Lamb, NYS IPM, with information from John Sanderson, and the ARS article “Greenhouse Pests Beware: Old World Hunter Fly Now in North America” by Luis Pons, October 2005
Photos – John Sanderson and Todd Ugine
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hunter fly
Hunter fly eating a fungus gnat.

There may not be any such thing as a free lunch, but some New York State greenhouse growers have discovered that they have free biological control of fungus gnats and shore flies. The Hunter Fly, Coenosia attenuata, was brought to the attention of Cornell entomologists in 1999, by Elise Schillo-Lobdell, who kept finding it on sticky cards in greenhouses she was scouting in Onondaga County. And in those greenhouses where it was identified, growers have noticed that they need fewer pesticide applications to control fungus gnats and shoreflies.

hunter fly
Hunter fly on sticky card.

The Hunter fly is originally from Europe and was probably brought to the US on plant material. Since the original introduction, the flies have spread throughout the US and Canada. In an informal survey in New York State, Hunter flies were found in at least 2/3 of the evaluated greenhouses. John Sanderson and his graduate students and postdocs, in the Entomology Department at Cornell, are working to find out more about its biology and behavior, so it can be used as a biological control agent.

For fungus gnat control, the Hunter fly is a double barreled biocontrol. The larvae develop in the soil, where they feed on fungus gnat and other larvae. The adults feed on flying insects, waiting until prey flies by and then catching them on the wing. They will feed on a wide variety of flying insects, which is the basis of one potential disadvantage – they may also feed on flying beneficial insects. Because fungus gnats and shore flies are often found flying - the same reason that sticky cards are good at catching them - the Hunter fly is particularly effective at controlling them.

So keep an eye out for Hunter flies in the air and on your sticky cards and you may find that you, too, have free biological control in your greenhouse.

Biocontrol Tour: Lessons from North of the Border

Betsy Lamb, NYS IPM
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View the tour as a 2Mb PowerPoint program

Ask any grower—biocontrol isn’t the first thing that comes to mind when you’ve got bugs in your greenhouses. In fact, biocontrol requires a major shift in grower thinking, says Albert Grimm of Jeffrey's Greenhouses in St. Catharine's, Ontario. “You must learn to anticipate the development of pests,” says Grimm. “Don’t wait until they’re already there.”

To help growers make that shift, a group of growers and Extension educators from New York visited greenhouses in both Ontario and New York that use biological control in August 2007. The tour was sponsored by the New York Farm Viability Institute and coordinated by the New York State Integrated Pest Management (IPM) Program and New York State Flower Industries.

Graeme Murphy, the Greenhouse Floriculture IPM Specialist for the Ontario Ministry of Agriculture, Food and Rural Affairs, started the tour with an introduction to biocontrol use in Ontario. There are about 1250 acres of ornamentals grown in greenhouses in Ontario, with 30-40% of that area in the Niagara Peninsula, where the tour was held. Biological control of insect pests in ornamental crop greenhouses started in the late 1980’s. Vegetable greenhouses had been using it since the 1970’s because of the bumblebees used for pollination and their susceptibility to insecticides. By1998, 20% of the ornamental greenhouses were using some type of biocontrol. And by 2007, Murphy estimates that it is over 50%. Why the big change? Some growers disliked using pesticides, but the majority was getting poor control with the limited number of insecticides labeled for their crops, because of insecticide resistance. So now in Ontario, you can find growers using biological control as one of their tools to control whitefly, thrips, aphids, and spider mites.. Why does it work? Because it has to, says Murphy, but also because there is available technical support in the area, and growers are creative, persistent - and patient.

A good example is Ed Boekestyn, of Boekestyn Greenhouses in Jordan Station, Ontario. He had a thrips infestation in his chrysanthemums that he just couldn’t keep under control with the available chemicals. But after he worked with a consultant to get a biocontrol system into place, he saw that not only did biocontrol keep the numbers of thrips down, it also slowed down how quickly resistance set in—meaning he could use chemical pesticides when he really needed them.. Would he have switched to biocontrol if he had had other options? “No,” he said. “But now I understand that if I’d used biocontrol, I wouldn’t have lost my chemicals.” And patience is key. “I used to want to spray everything. Now I just wait for the natural balance. After you get started, you get beneficials working for you.”

No two systems are exactly the same. Each grower adapts biological control methods to meet their own needs. To manage whiteflies in his cut gerbera crop, John Hofland of Orchardcreek Greenhouses in Beamsville, Ontario finds that the small black beetle, Delphastus, works better for him than the more commonly used wasps Encarsia or Eretmocerus. And over at Waldan Gardens in Wainfleet, Bob Newhouse produces his own banker plants, rather than buying them, to support populations of Aphidius colemanii, which parasitize aphids in his kalanchoe crop. Even when the beneficials are applied can vary. Vince Suglioat Ravensbergen and Sons Greenhouses in Smithville Ontario, emphasizes the concept of “loading”—using high numbers of beneficial insects when the plants are small and grouped pot-to-pot—so the beneficials can move easily from one plant to the next, helping keep those early pest problems from getting out of hand.

Retail greenhouses like Lucas Greenhouse have limitations on what can be sprayed and when it can be done because they are open to the public. The tour stop at Mischler’s Greenhouse in Williamsville, NY demonstrated that biological control is also relevant in retail greenhouses growing a wide variety of crops. Mark Yadon, who has been managing the greenhouse at Mischler’s since2001, releases predatory mites and wasps to control aphids, thrips, whiteflies, spider mites, and fungus gnats in a greenhouse often filled with customers. In fact, he even gets volunteer beneficial insects coming in from outside. He's found at least 3 species of parasitic wasps and Hunter flies on his monitoring traps. And even a good biocontrol system is subject to change. Dave Mischler first used Encarsia formosa to control greenhouse whitefly in 1989. But when the predominant whitefly species switched to sweet potato whitefly, the wasp was no longer effective. Even beneficial insects have food preferences. Now they release both Encarsia formosa and Eretmocerus mundus to keep all the whiteflies in check.

Although most greenhouses on the tour specialized in ornamentals, Len Krijsman at Gro-Max Greenhouses grows European cucumbers. He introduces a combination of predaceous mites to the greenhouse as soon as the cucumbers are planted – Amblyseius swirskii to control thrips and whitefly, and Amblyseius californicus to keep spider mites under control. That tour was almost over when Carol Glenister, who raises and sells beneficial insects at IPM Labs in Locke, NY, asked the group what they noticed about the insect control among the cucumbers. The group was silent. “That's right,” she said. “Nothing. That's good biological control!”

New Floriculture Faculty - Neil Mattson

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Neil Mattson

Neil Mattson has recently accepted the new Floriculture position in the Horticulture Department at Cornell University. He comes to Ithaca from Davis, California where he completed his Ph.D. in a project studying nutrient use by cut flower roses. While at Davis, he also worked on a computer program to schedule production of roses using degree days. This helps growers to produce as many flower stems as possible for important holidays, such as Valentine’s Day. Neil brings with him his wife, Janelle, and they are expecting their first child in November. While Neil lived most recently in California, he is no stranger to northern climates. He grew up in northern Minnesota on a small beef farm. His Master’s degree was from the University of Minnesota where he studied the effects of light and temperature on growth and flowering of bedding plants.

Neil’s appointment at Cornell is split 60/40 between research and extension. In research, he is interested in nutrition management of bedding/potted plants to reduce inputs and mitigate runoff from horticultural facilities. As energy costs continue to be a concern, he’s also interested in strategies to produce high quality ornamentals while reducing energy inputs. Some techniques that show promise include: grouping together plants with a similar temperature response, providing supplemental light treatments while plants are in the plug stage so they will finish earlier once transplanted; and improved temperature scheduling to streamline production and reduce the number of days a crop needs to spend in the greenhouse. Neil will be active in extension and hopes to meet many of you at grower conferences, field days, and etc. Neil will also be conducting a survey of greenhouses in New York to determine their priorities for floriculture research and extension activities. Neil is available by phone at (607)255-0621 and email at

Christmas Tree Growers Workshop

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Wednesday, October 31, 2007

LOCATION, Route 40, Easton

Kuzmich Christmas Tree Farm, Cheese Factory Road, Easton NY


8:30 – 9:00 Registration and sign up for DEC re-certification credits

9:00 – 10:00 Developing a Weed Management Plan – Dr. Elizabeth Lamb, NYS IPM Program

10:00 – 11:00 IPM for Christmas Trees: Recognizing Insect and Disease Pests – Gary Couch, NYS IPM Program

11:15 – 11:30 Break

11:30 – 12:30 Pesticide Inspections: How the NYS Tree Grower Should be Prepared – John Bennett, NYS DEC, Region 5

12:30 – 1:00 Lunch (Participants can use lunch time for individual Q&A with NYS DEC representative)

1:00 – 1:45 Christmas Tree Species and the Things You Should Know About Them– Laurel Gailor, CCE Warren County

1:45 – 2:00 Break – Drive to Kuzmich’s Tree Farm

2:00 – 2:30 Pruning Techniques – David Kuzmich, Kuzmich Christmas Tree Farm

2:30 – 3:00 Identifying Pest Problems in the Field – Gary Couch, NYS IPM Program

3:00 – 3:30 Sprayer Calibration Exercise – Laura McDermott, CCE Washington County

3:30 – 3:45 Program Evaluation and recertification credit sheets distributed - Adjourn

Contact Laura McDermott for more information. Phone: 518-746-2560

2007 Empire State Green Industry Show

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The largest green industry show in New York State, the Empire State Green Industry Show, hosted by the New York State Nursery and Landscape Association, New York State Turfgrass Association, New York State Arborists and New York State Flower Industries, will be held at the Rochester Riverside Convention Center on November 13 - 15, 2007.

Accredited Education: This is a great educational opportunity for all aspects of the Green Industry. The Empire State Green Industry Show features accredited education sessions for all green industry professionals and a Trade Show with over 120 exhibitors. A total of 42 DEC credits will be available. ISA and CNLP credits will also be available.

Registration: Conference registration and hotel reservations are now being accepted! It's not too early to book! To register, go to The Empire State Green Industry Show website to download exhibitor and conference registration brochures.


Cornell IPM Team for Production Ornamentals
Betsy Lamb
State Coordinator for Ornamental Crops IPM
Ithaca, NY,
Gary Couch
Eastern New York Specialist
Brian Eshenaur
Western New York Specialist
Rochester NY
Disclaimer: Pesticide recommendations are for informational purposes only and manufacturers' recommendations change. Read the manufacturers' instructions carefully before use. Cornell Cooperative Extension and Cornell University assume no responsibility for the use of any pesticide or chemicals.
Some of the links provided are not maintained by Cornell Cooperative Extension and Cornell University. Cornell Cooperative Extension and Cornell University are not responsible for information on these websites. They are included for information purposes only and no endorsement by Cornell Cooperative Extension or Cornell University is implied.
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