Apr 25, 2011 | View All Issues
We sampled GMB at the end of last week (Apr 21, 22).
At our Oakville site, 100% of the GMB population was on the spurs. They were 1st and 2nd instars.
At our Oak Knoll site, 90% of the GMB population was on the spurs and 10% of the GMB population had moved onto the leaves. They were 1st and 2nd instars.
Insecticide treatments are most effective against exposed mealybugs (on the leaves). For growers concerned with GMB as a vector of leafroll virus, the first treatment window for foliar insecticide applications is approaching and will be optimal when the GMB are exposed on the leaves. (This does not include Movento applications, which require a more expanded canopy for absorption).
In vineyards where leafroll virus is not a concern, and GMB populations are not economically damaging, avoid unwarranted insecticide application to protect the GMB natural enemy complex.
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