Apple flea weevil begins spring emergence

MSU research is underway to help growers manage this emerging pest.

The apple flea weevil has begun emerging in at least two Michigan apple orchards: one near Pottersville and the other near Berrien Center. Trees at both sites were in quarter-inch green when weevils were first observed. Adult weevils have begun mating and tend to aggregate on buds. It is unknown whether they are damaging buds at silver or green tip, but based on laboratory observations, they are capable of damaging buds beginning at pink.

The organic pest management laboratory at Michigan State University has initiated research to determine the life history, phenology, reproductive behavior, damage thresholds, and management of this pest. We are also researching apple flea weevil monitoring techniques. At present monitoring is best accomplished by visually inspecting the trunk, branches and buds. Beat sheets may also be used.

Here are the results of laboratory screenings conducted this winter. OMRI listed compounds are noted with an asterisks (*).

Entrust®*, Pyganic®*, M-pede®*, Delegate®, Danitol®, Guthion®, and Assail® killed 90% or more of apple flea weevil adults exposed to wet residue but Pyganic® and M-pede®* had no efficacy when dry.

Lime Sulfur*, Mycotrol®*, Neem oil*, and Avaunt® did not kill weevils.

None of the tested compounds are labeled for apple flea weevil at the present time.

Read our previous article, Emerging pest alert: The apple flea weevil for more information on the apple flea weevil.

Adult apple flea weevil on a bud at silver tip taken on April 14, 2011 by a grower in central Michigan.
Photo of an adult apple weevil on bud at silver tip taken on April 14, 2011 by a grower in central Michigan.

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