2018 Greenhouse disease and insect management recommendations
Insect and disease management recommendations and impatiens downy mildew preventative spray programs for the 2018 growing season.
Michigan State University Extension entomology specialist for ornamentals David Smitley has released his “2018 Greenhouse Insect Management” document. These are the recommended products to control thrips, aphids, whiteflies, spider mites, broad and cyclamen mites, fungus gnats, mealybugs and Florida fern caterpillar.
MSU Extension plant pathologist Mary Hausbeck has released her new “Greenhouse Disease Management 2018 Season” recommendations. The products are classified as either “A” or “B” team products. The “A” team products provide the best control for the diseases, and “B” team products are those that provide control and are good to include in a spray rotation. New for 2018, Hausbeck included the FRAC codes, which indicates the mode of action of the fungicide. FRAC codes are number or number/letter combinations that are assigned by the fungicide resistance action committee (FRAC), which groups products with similar active ingredients together and demonstrates the potential for cross-resistance. Rotate chemicals with different modes of action to prevent disease resistance.
In addition to the overall disease management recommendations, Hausbeck has also released the “2018 Greenhouse Impatiens Downy Mildew” recommendations. This document provides a rotation of products that are effective in preventing impatiens downy mildew. It provides information on the rates and frequency of the products listed. These recommendations are similar to those of 2017, but with a few additional notes.
Resistance management is a very important issue facing not only individual growers, but the industry as a whole. In order to prevent disease and insect resistance, always remember to rotate modes of action in a disease or insect management program. For example, growers should be extra careful when managing western flower thrips and twospotted spider mites. These insects are greenhouse pests that can develop resistance easily.
With respect to disease, there has been documentation of strains of Pythium found in Michigan greenhouses that are resistant to mefenoxam (Subdue MAXX). Growers should be documenting rates and timing of pesticide applications and be making notes on efficacy.
If you have questions about these insect and disease management recommendations, contact your local MSU Extension greenhouse educator.