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Hessian Fly Damaged Wheat (08/13/15)

Several emails and calls about lodged wheat from Hessian fly infestations have been reported in primarily Pembina and Williams counties.

Hessian Fly Damaged Wheat

Several emails and calls about lodged5.ent.knodel.fly wheat from Hessian fly infestations have been reported in primarily Pembina and Williams counties. Some Hessian fly infested fields have 40-50% of stems lodged. Hessian fly is occasionally an insect pest of wheat in North Dakota, and is more common when we have wet weather in May-June. Damage symptoms to look for is wheat lodged at the second or third node and a small ‘flaxseed’ pupa inside the leaves on stem (see photograph on right). Please send in any other reports of Hessian fly.

The Hessian fly overwinters as a maggot or pupa in winter wheat, volunteer grain, and wheat stubble. Overwintering maggots pupate and emerge as adults from April to May, infesting fall and spring planted wheat. By August, maggots pupate (flaxseed stage), emerging as adults in late August to lay eggs for the overwintering generation in winter wheat or volunteer wheat.

The following recommendations are used to manage Hessian fly:

Winter wheat planting date:  Winter wheat will act as a bridge to get Hessian fly from one season to the next. Delaying planting in the fall should reduce the risk of infestations. Suggested planting dates for ND are: north - September 1 - 15; and south - September 15 to 30.

Tillage:  Burying stubble and destroying volunteer grain after the first killing frost or early in the spring before fly emergence helps suppress adult populations.

Crop Rotation:  Rotate wheat with non-susceptible host crops (oats, canola, corn, flax, soybean, and sunflower).

Resistant varieties:  Russ HRSW, released by SDSU in 1995, is an early maturing variety with Hessian fly resistance. Consult with your local seed company for other new varieties.

Chemical control:  Imidacloprid and thiamethoxam are registered as active ingredients for use at planting time treatment or as a seed treatment on wheat. Warrior II is also labeled as a foliar application when adults emerge. However, population levels of this pest would rarely warrant the need for such treatments in North Dakota, and timing of application is difficult due to the wide emergence window.

Janet J. Knodel

Extension Entomologist

 

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