From the Field
Ways to Reduce Drift
Friday May 15, 2026
Spray drift is one of the most important issues facing pesticide applicators. Movement to off-site locations can be caused by wind, poor calibration/adjustment, and operator error.
Use Pesticides Wisely to Avoid Resistance
Friday May 08, 2026
Repeated use of pesticides with the same mode-of-action used in the orchard can accelerate the development of insecticide resistance. WSU recommends that when you choose insecticides, keep track of which ones are being used so that you alternate materials with the different modes-of-action (shown in DAS) between generations.
Bt Applications for Leafrollers
Friday May 08, 2026
Bacillus thuringiensis (Bt) is a bacterium that must be eaten by lepidopteran larvae (caterpillars) to be effective. Bt is a great material for leafroller control because it is specific and has little effect on natural enemies. However, it must be applied 2-3 times to be effective when leafroller populations are high. Experience has also shown that in the spring, the high temperatures need to be above 65°F for 3 or more days so that larvae have a chance to feed on it before sunlight breaks it down. DAS provides forecast temperatures for all stations in the "Weather Forecast" and in the "Show Data Grid" table so that you can decide whether or not to use Bt or other recommended chemicals.
What is DAS?
The Decision Aid System (DAS) is a collaborative project between WSU Extension, the WSU Agricultural Research Center, and partners in agricultural industries. The DAS is a web-based platform designed to transfer time-sensitive information to decision makers. We run insect, disease, disorder, and horticultural models to predict on-farm conditions in real time, and link these site-specific forecasts to appropriate management and pesticide guidelines.
