Managing SWD Using Reduced Spray Strategies

Since the invasion of Spotted Wing Drosophila (SWD), Drosophila suzukii, blanket applications of broad-spectrum pesticides are made between 2 and 8 times per season to protect susceptible fruit from infestation. As a consequence, growers are faced with the challenges of managing harvest around pesticide preharvest and restricted entry intervals; disruption of current IPM programs; increased secondary pest outbreaks; increased production costs; fruit knockdown from sprayers traveling down rows; and greater risks to environmental and human health. Reduced pesticide application strategies may mitigate some of these challenges. Field studies were conducted from 2011 to 2013 to determine (1) if reduced spray programs manage SWD as well as conventional blanket sprays and (2) the economics of the reduced spray programs. Three raspberry sites and one blueberry site were alternate-row middle sprayed and border sprayed, respectively, and compared to blanket sprays during the harvest season. SWD adults and larvae, non-target arthropods and fruit knockdown were quantified. Reduced pesticide strategies such as alternate-row middle and border sprays show promise as a replacement to blanket sprays for SWD management while reducing spray area, application time and production costs.