KIMBERLY, Idaho-Dr. Erik Wenninger, Extension Entomology Specialist with UI-CALS in Kimberly is reporting that Colorado potato beetles were observed in Kimberly late last week. So far, only overwintered adults have been observed, and they will do little damage to potatoes. Scouting should begin soon for eggs and for larvae, which can cause considerable damage.
To guard against development of insecticide resistance, post-emergence applications of neonicotinoid insecticides should not be used if a neonicotinoid seed treatment or other at-planting neonicotinoid treatment was used. Examples of neonicotinoid seed or at-planting treatments include Admire, Belay, Cruiser, Gaucho and Platinum. Examples of foliar neonicotinoid sprays include Actara, Belay, Endigo ZC, Leverage and Provado.
Those using "soft" chemistries against Colorado potato beetles should be especially vigilant about scouting to appropriately time sprays. Sprays against the first generation should be applied when the first mature larvae are seen; at this time most of the larvae have hatched, but are still relatively small and susceptible to insecticides.
Border sprays may be considered if populations have not spread into the interior of fields.