Greenhouse disease and insect management recommendations for 2021

Insect and disease management recommendations for the 2021 growing season.

Greenhouse
Photo by Heidi Lindberg, MSU Extension

Michigan State University Extension has updated their insect and disease management recommendations for the 2021 greenhouse season. There have been some changes from the previous 2020 recommendations. These recommendations are updated yearly to reflect efficacy of pesticides as MSU Extension specialists and their nationwide colleagues perform research trials evaluating the products against common greenhouse insects, mites or diseases. The pesticides are evaluated by a network of researchers involved in the IR-4 Project, a research group that facilitates the labeling of pesticides on specialty crops, including greenhouse crops.

Insect management

MSU Extension entomology specialist for ornamentals, David Smitley has released his “2021 Greenhouse Pest Management with Insecticides” recommendations. These are the recommended products to control thrips, aphids, whiteflies, spider mites, broad and cyclamen mites, fungus gnats, mealybugs and Florida fern caterpillar.

Growers of greenhouse vegetables and greens can use the guide, “Recommended Insecticides for Common Greenhouse Pests on Vegetables, Herbs and Leafy Greens,” when considering an insecticide application. The guide provides the names of the products, active ingredients, vegetable crops on the label and recommended pests they control. For more information on the guide, see the MSU Extension article, "Insecticides for common pests on greenhouse vegetables and transplants."

Download 2021 Greenhouse Pest Management with Insecticides Recommendations

Changes from 2020

There are four changes from the 2020 recommendations for greenhouse insect control. They include new products with novel modes of action and those that have now received a label for greenhouse and ornamental use:

  • Notavo (clofentazine) is the new name for Applause, which was on previous year’s recommendations. The product has been added for spider mite control and has the same active ingredient that is in Apollo. These products contain clofentazine which is in the class of tetrazines which have an IRAC Group number of 10A. Resistance should not be a problem.
  • Ventigra (afidopyropen) earned an EPA label in 2018, it is a new insecticide to the greenhouse industry and is now listed for aphids, whiteflies and mealybugs. Plants sensitive to Ventigra include coleus, poinsettia (in bract), and impatiens and petunias when in flower. The insecticide is in the group 9D and is a good choice to manage resistance when in a rotation.
  • Sarisa (cyclaniliprole) has been added for control of thrips, whiteflies and mealybugs.  It has also been recently labeled for use in greenhouses. It is an IRAC group 28 insecticide.  Other greenhouse products that belong to that group are Acelepryn (chlorantraniliprole) and Mainspring (cyantraniliprole).
  • Pradia (cyclaniliprole and flonicamid) is a combination product containing the novel IRAC group 28 active ingredient, cyclaniliprole. It also contains the active ingredient  in Aria so using it would be like using Sarisa and Aria together.

Disease management

MSU Extension plant pathologist Mary Hausbeck has released her new "2021 Greenhouse Disease Management" recommendations. The products are classified on a range from “A+” or “B/B-” team products. The “A” team products provide the best control for the diseases, and “B” team products are those that provide limited control and are good to include in a spray rotation. 

Hausbeck has also provided an updated “2021 Greenhouse Impatiens Downy Mildew Program” for both susceptible and impatiens downy mildew-resistant cultivars.

Hausbeck and her colleagues have also developed a guide for disease management specifically for vegetable and herb crops. The guide provides the following information about each registered product for vegetable transplants and herbs: 1) active ingredient, 2) trade name of the product, 3) FRAC code (a guide for alternating products to delay/reduce pathogen resistance) and 4) re-entry interval. The disease recommendations are grouped by crop groups: 1) brassica, 2) cucurbit, 3) leafy, 4) fruiting and 5) herbs. Within each crop grouping, the table includes the target pathogen including: bacterial blight, downy mildew, leaf spot, powdery mildew, Phytophthora, Rhizoctonia and Sclerotinia.

Download 2021 Greenhouse Disease Management Recommendations

Changes from 2020

The disease management recommendations are very similar between 2020 and 2021. For powdery mildew management, Broadform (fluopyram + trifloxystrobin) is a new addition to the “A/A-“ team and is another product with the FRAC code of 7 and 11.

The number of recommended products to manage bacterial diseases has been reduced from six products down to three products. The only recommended products to prevent the spread of bacterial diseases such as Xanthomonas are CuPRO 5000, Nordox 75WG, and C-O-C-S. These products have the highest percentage of metallic copper and are therefore more effective at preventing disease.

For the management of impatiens downy mildew on susceptible cultivars, Michigan State University Extension recommends a similar program compared with other years, however, the recommendations are for fungicide drench applications on Days 1, 7, and every 14 days as well as shortly before shipment. Impatiens cultivars, such as Imara XDR and Beacon, are not susceptible to impatiens downy mildew. These cultivars were included in many nationwide trials during 2019 and provide an excellent choice especially for use in landscape sites that may be infested with the impatiens downy mildew. As an insurance policy, growers may want to consider a single application of Subdue Maxx and Segovis.

If you have questions about these insect and disease management recommendations, contact the author or your local MSU Extension greenhouse educator. You can also find more information on crop safety and efficacy of products on the Environmental Horticulture Research Summaries page of the IR-4 Project website.

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