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UMass Extension Landscape Message April 27, 2012

UMass Extension Landscape Message April 27, 2012

"Winter Moth remain active but it now appears that in many cases, the early hatch, cold weather, and lack of food has lead to the demise of many caterpillars. Small numbers of winter moth caterpillars can be found throughout the range of Winter Moth in MA and scattered pockets of larger numbers do exist. Inspections should be made first to determine if control measures are necessary. The much-needed rainfall from earlier this week is helping new foliage to now expand and begin to outgrow feeding damage. For infested plants with opened or opening buds, a spray of Bacillus thuringiensis Kurstaki (B.t.K.) can be quite effective. However, B.t. needs to be ingested by the caterpillars to be effective and if the foliage is not yet near to being fully expanded, then wait for that to happen. Otherwise, the new foliage material that appears over the next several days, after spraying B.t., will not be covered with B.t. thus allowing the caterpillars more leaf surface to damage before ingesting the pesticide. An application of a product that contains Spinosad as the active ingredient should provide excellent results at this time or in the coming weeks during the caterpillar feeding stage. Many pyrethroid insecticides are labeled for caterpillars as well. Avoid spraying apples and crabapples with Spinosad or pyrethroid products if they are in bloom. Pyrethroids can be very harsh on pollinators, such as bees. Spinosad products are toxic to bees at the time of application but this threat diminishes significantly 24 hours after application."

Claire