|K-State Research and Extension Horticulture Newsletter
A spreader-sticker is used to improve the distribution and retention of fungicides and insecticides on fruit and leaves. Many gardeners may not be familiar with these products but they can help our fungicides and insecticides work better. Look for a product that is called “Spreader-Sticker.” Big box stores rarely carry these products but garden centers or well-stocked hardware stores often do. These products should be used with fruit tree sprays as it allows the spray to coat leaves and fruit more thoroughly and to resist being washed off during rain events. However, even with a spreader-sticker, a rain can reduce the length of time the materials are effective. Less than one inch of rain since the last spray will not significantly affect residues. As a general rule, one to two inches of rain will reduce the residue by one half. Reduce the number of days until the next spray by one half. More than two inches of rain since the last spray will remove most of the spray residue. Re-spray as soon as possible. These recommendations apply for a soft, gentle rain. If you have a hard, driving rain, cut the above recommendations in half. (Ward Upham)
Cynthia Domenghini runs the Horticulture Response Center in the Department of Horticulture and Natural Resources at Kansas State University. Other contributors include K-State Extension Specialists.