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Armyworms in Wheat and Barley (07/09/15)

Armyworms are becoming a concern in maturing wheat and barley fields in Cass, Grand Forks and Steele Counties of North Dakota.

Armyworms in Wheat and Barley

Armyworms are becoming a concern inent.knodel.5.armyworm larva maturing wheat and barley fields in Cass, Grand Forks and Steele Counties of North Dakota. This moth migrates into North Dakota and infestations can be sporadic. Most fields with armyworms have low numbers and defoliated leaves are only being reported along field edges and in lodged areas of fields. Although mature armyworm larvae can clip heads, low levels of head clipping has occurred. As the crop matures, head clipping may become more common. Both small and large armyworms are being found so scout infested fields frequently until harvest. Pre-Harvest Intervals (PHI) are important and limits which insecticides are available for armyworm control (see Table below). Malathion and Lannate (Restricted Use Pesticide) are the only two insecticides registered in barley and wheat with a short PHI of 7 days, and Prevathon with 14 days. Since armyworms are active feeding at night, spray in early evening and use adequate water volume to get the insecticide into the crop canopy (3-5 gallons per acre by air). The current economic threshold is 4-5 armyworms per square foot in barley and wheat. For more information, please see Dr. Ian McRae’s fact sheet on armyworms in Minnesota.

ent.knodel.6.insecticide table

Janet J. Knodel

Extension Entomologist

 

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