Bird cherry-oat aphids and greenbugs on wheat
Approximate Damaging Levels of Greenbugs
Stage and development of plants No. of greenbugs per linear foot
Seedlings, thin stands less than 3 tillers 50
3- to 6-inch wheat, 3 tillers or more 100 to 300
6- to 10-inch wheat 300 to 500
Overwintering greenbugs can rapidly develop into damaging infestations during warm periods in February and March, and close surveillance of fields is necessary if greenbugs are present. Beneficial insects such as parasitic wasps and ladybeetles become increasingly effective in reducing greenbug populations around mid-April. Once parasitism levels reach between 10 and 15 percent, greenbug populations usually decline fairly rapidly.
Greenbug control on small grains is occasionally needed during periods of relatively cool weather (below 60°F, but above freezing). Experience has shown that good results are possible under these conditions with some, and perhaps most, of the recommended insecticides. Dimethoate may be an exception, however. It may not give acceptable control below 60°F.
Oklahoma State University has developed a sampling program called “Glance ‘n’ Go,” which calculates a greenbug threshold based on the cost of control, the market value of wheat and the month of the year. For more information on their greenbug pest management decision support system, see the web site at: http://entoplp.okstate.edu/gbweb/.
Consider avoiding pesticide applications when beneficial insects such as lady beetles and parasitic wasps are active, as these are often abundant enough to prevent greenbugs from reaching damaging levels. Augmenting greenbug predators such as ladybeetles or lacewings by importing and releasing is not advisable.
For more detailed information on bird cherry-oat aphids and greenbugs, see:
For specific treatment options, see K-State publication “Wheat Insect Management 2012” MF-745 at: www.ksre.ksu.edu/library/ENTML2/MF745.PDF
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