San Jose Scale crawler update July 10
The first crawlers have been observed in Grey County! The timing for summer sprays aimed at crawlers has arrived for orchards with a history of scale infestations. Scales have also been identified on new growth in Norfolk County.
In 2014 the Cornell model was approximately a week ahead of crawler emergence- the Washington State (WA) model using the first adult catch as the biofix was more accurate in predicting emergence. Regarding Grey County, it appears the NY was approxiamtely 2 weeks ahead of crawler emergence. Summer insecticides Movento, Closer, and TwinGuard should target these crawlers. Movento is a slower acting insecticide and can be applied at the first sight of crawlers, if not earlier. This generation of crawlers can last for up to six weeks, so reapplication of Movento in 14 days is optimal. Using Closer or Twinguard, growers can wait for a week after the first crawlers are found to target a larger number of emerged crawlers. Keep in mind that Twinguard contains Delegate when planning product rotation. More information on insecticides can be found in Chapter 3 of Pub 360.