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Update on Alfalfa Weevil Degree Days (06/18/20)

The degree day map (below) shows that alfalfa weevil larval feeding is past the peak period based on accumulated degree days (ADD).

The degree day map (below) shows that alfalfa weevil larval feeding is past the peak period based on accumulated degree days (ADD). Peak feeding occurs between 504 - 595 ADD when larvae are mature, 3rd to 4th instars (Table 1). Most of ND is >600 ADD, so no alfalfa weevil control is recommended in those areas. Larvae will start pupating (non-feeding stage) at 814 ADD. The recent, hot temperatures have pushed the rate of insect development. Some alfalfa is being cut this week. Early cutting of alfalfa is one of the best pest management strategies to reduce feeding damage from alfalfa weevil.

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Janet J. Knodel

Extension Entomologist

 

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