With continued concern over little cherry virus it is important that we control the vectors – apple and grape mealy bug.
Researchers tested several approaches to controlling the apple mealybugs: delayed dormant pesticide applications to intercept overwintering females; systemic petal fall applications to target crawlers; and foliar summer sprays timed when 70 percent of the crawlers are estimated to have emerged.
In the 2014 trial, a combination of Lorsban and oil was found to be most effective at the delayed-dormant stage. Diazinon worked best at controlling the newly hatched crawlers later in the summer. They repeated the research in 2015 to the same results, with one addition: A combination of Centaur and oil also was effective at the delayed-dormant stage. Lorsban is rated as high toxicity on natural enemies. No ratings were found for Centaur.
For grape mealybug, systemic compounds, Admire Pro (soil drench) and Ultor and oil, applied 14 days after petal fall showed the best results.
In general delayed dormant oils were not as successful as hypothesized. Please keep in mind that efficacy ratings will be continually refined as more information becomes available.
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