Researching Pest Problems

The research program of Kansas State University’s Dr. Raymond A. Cloyd focuses on discovering and implementing new methods to effectively manage greenhouse insect and mite pests with minimal pesticide inputs. His current research involves, although not limited to, evaluating the following:

■ Compatibility of pesticides including insecticides, miticides and fungicides with biological control agents (natural enemies). This research is designed to assess the lethal (immediate) and sub-lethal (long-term) effects of commercially available insecticides, miticides and fungicides on specific natural enemies. For example, research has shown the miticides bifenazate (Floramite), spiromesifen (Judo) and chlorfenapyr (Pylon) are not harmful to the predatory mite, Neoseiulus californicus; but are toxic to Phytoseiulus persimilis.

■ Impact of tank-mixing pesticides (insecticides, miticides and fungicides) for control of insect and mite pests. This research addresses the issues related to tank-mixing pesticides, such as how pesticide mixtures, including two- and three-way combinations, impact control of arthropod pests.

■ Quality of commercially available biological control agents sold to greenhouse producers. This research has demonstrated that the quality, based on percent survival, of commercially available entomopathogenic nematodes, in this case, the species Steinernema feltiae, can vary depending on the supplier.

■ Effect of silicon applications on the reproduction and development of arthropod pests feeding on horticultural crops. This research involves determining if foliar and/or drench applications of potassium silicate negatively affect the reproduction and development of the citrus mealybug, Planococcus citri and greenhouse whitefly, Trialeurodes vaporariorum, when feeding on certain plants.

Downy Mildew Management

Mary Hausbeck and Blair Harlan at Michigan State University and Margery Daughtrey at Cornell University are studying management of the new downy mildew (DM) disease on coleus with funding from the American Floral Endowment. Both seed-grown and cutting varieties are under assault by this new Peronospora species. The disease was widespread in the industry in 2006 but many growers did not recognize the problem. The coleus DM has been found to be the same species that is affecting greenhouse crops of basil in Europe. Host range trials in New York have shown that the new DM will also attack agastache hybrids currently in the trade. Environmental regulation may be key.

Spore-trapping studies in Michigan are looking at the how the number of spores in the greenhouse atmosphere correlate with environmental parameters such as temperature, humidity and leaf wetness. Fungicide trials in New York have indicated, SubdueMAXX drenches and sprays of Fenstar and StatureDM to be especially effective. Trials in Michigan have corroborated the effectiveness of Stature DM and SubdueMAXX, and have also seen benefit of spray treatments with BAS 516, Insignia and Pentathlon LF. From their results, programs using rotations of Stature DM and a mancozeb appear to be the most effective option.

Whitefly Management

Dr. Scott Ludwig is an Extension Program Specialist-IPM with Texas Cooperative Extension in Overton, Texas. He serves as a member of the Technical Advisory Committee of the Whitefly Biotype Q Task Force, where he is co-coordinator of the education subgroup. USDA-ARS has funded a national effort to develop a science-based whitefly management plan comprising both chemical and biological control techniques. He is currently evaluating the impact of insecticide residue on silverleaf whiteflies and common natural enemies found in ornamental systems. These projects should extend the life of the effective insecticides used against whitefly control while reducing grower inputs in the pest management programs.

This spring, Dr. Ludwig will start a program looking at insecticide resistance in western flower thrips and Madeira mealybugs. He recently started a pilot program with the IR-4 Seed Treatment program to evaluate the effectiveness of insecticide-coated ornamental seed, which would provide four to eight weeks of insect control without additional pesticide applications.

To provide Texas producers with science-based pest management recommendations, he conducts research and demonstration trials evaluating herbicide and insecticide efficacy and crop safety at grower and University facilities. This work has been funded though the Northeast Texas Nursery Growers Association, the Texas IPM Program, USDA–ARS and its Floriculture Research Initiative, the IR-4 Project and commercial companies. etipm.tamu.edu.

Reduced Risk Pesticides

Michael Parella’s laboratory in the Department of Entomology at the University of California, Davis focuses on developing and implementing IPM strategies in floriculture crops with an emphasis on biological control. This includes traditional areas such as development of sampling plans, economic thresholds, evaluation of biological control agents, compatibility of biological control agents with pesticides, etc.

This program differentiates itself from others in its attempts to include other aspects, such as fertilizer inputs, water quality and post harvest life of flowers – best management practices for cut flowers. The lab has several joint projects with horticulturists, soil scientists and plant physiologists on the Davis campus. The lab also maintains colonies of the major pests and works with the agchem industry and the IR-4 program in screening "reduced risk" pesticides and in determining their compatibility with natural enemies. Students and staff are working with developing complete programs for cut and potted gerbera through the creation of the Gerbera Alliance and anticipate developing a Bedding Plant Alliance.

Specific projects include an evaluation of silicon added to the fertilizer mix to improve host plant resistance, an analysis of the lady beetle, Psyllobora vigintimaculata, as a biological control agent of powdery mildew, studying the biology and control of the iris whitefly, biological control of leafminers through the use of the sterile insect technique and parasitoids, and the development of an identification key for invasive thrips species that can be used by regulatory personnel at ports of entry to prevent the introduction of exotic thrips species. 

Sustainable Pest Management

Developing cost-effective and sustainable pest management programs for greenhouse pests is the central mission for John Sanderson’s research and extension program at Cornell. With funding support from the USDA Floral and Nursery Research Initiative, the Gloeckner Foundation, the Post/Schenkel Foundation and IR-4, Sanderson’s program is collaborating with the lab of USDA–ARS scientist Stephan Wraight to fight greenhouse pests. The lab is evaluating pesticides for use against Q-biotype sweetpotato whitefly and western flower thrips, among other pests. After discovering a non-native "hunter fly" in greenhouses across North America and beyond, the researchers are learning how this voracious predator might be used to control greenhouse pests such as fungus gnats and shore flies.

They are also evaluating the use of "banker plants" or "open-rearing systems" to cheaply and simply generate natural enemies for cost-effective control of greenhouse pests such as thrips, aphids, whiteflies and fungus gnats.

Cooperating with Margery Daughtrey, Cornell researchers are looking at the interactions between plant root health, fungus gnats and root rot pathogens to learn how to minimize crop losses. Several insect fungal pathogens are being evaluated for control of pests including aphids, shore flies and whiteflies, and whether it is possible to integrate applications of these pathogens with the use of other natural enemies for optimal pest control. 

Active Ingredient Tests

The objective of Mary Hausbeck’s lab is to characterize the efficacy of new active ingredients including reduced-risk fungicides, biocontrol agents or biopesticides against Botrytis cinerea, Pythium spp., Phytophthora spp., powdery mildew and downy mildew pathogens. Thirty-two products, 13 registered, 19 unregistered (of which 13 were experimental) were tested in efficacy trials.

One trial tested 12 treatments of fungicides for the control of Botrytis on geranium. Daconil WeatherStik F (chlorothalonil) and Decree WDG proved especially effective. Three trials tested 31 treatments of fungicides alone and in combination for the control of Pythium on geranium and poinsettia. Subdue MAXX 2EC alone or in combination with Heritage 50WG, Truban 30WP and an experimental product from Valent effectively limited Pythium root rot. One trial tested 33 treatments of fungicides for the control of Phytophthora on snapdragon and Fenstar and experimental products from Syngenta and Valent significantly reduced plant death.

Two trials tested 16 treatments of fungicides applied alone and in combination for the control of downy mildew (Peronospora sparsa) of rose. Applications of Daconil WeatherStik, Heritage WDG, Stature DM, Junction DF and an experimental chemical from Syngenta in combination with Heritage and/or Subdue Maxx were especially effective for downy mildew control. Eagle, Terraguard and an experimental from BASF were found to be effective treatments for powdery mildew on African daisies and verbena.

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