Hessian flies threaten fall wheat in North Texas

North Texas wheat fields could be damaged by Hessian flies this fall, said an expert with Texas Cooperative Extension.

Infestations were unusually high in the area during the spring, which indicates that the tiny flies are likely to pervade wheat fields in coming months, said Extension entomologist Dr. Allen Knutson, who is based in Dallas.

"We expect large numbers have over-summered in wheat stubble and will soon be emerging to infest planted wheat fields this fall," Knutson said.

Producers should be concerned because adult flies can travel easily, he said. Although as small and delicate as a mosquito, the insect can fly or be carried by the wind up to a mile in search of wheat.

Hessian flies have been in Texas for more than 100 years, Knutson said. They are minor pests in most years, but a widespread outbreak occurred during the spring.

"The 2007 wheat crop looked excellent in April, but then damage by Hessian flies reduced yields by 25 to 75 percent in many area fields," said Jim Swart, an Extension entomologist who specializes in integrated pest management. Yield potential in some fields were so low they were baled for hay, Swart said.

Growers, however, can protect the crop if they plan quickly. "There's no magic bullet that you could use to protect wheat from infestation, but there are some management practices that can be employed to reduce the risk," Knutson said. Knutson and Swart offered the following advice:

- Delay planting. Hessian-fly activity declines with cooler temperatures in late October and November. Waiting until late October to plant could help.

- Destroy volunteer wheat. Doing so would eliminate a primary host and prevent them from flying to nearby planted wheat to lay eggs.

- Select varieties with genetic resistance to the flies. Knutson and Swart evaluated infestations in several varieties in the Dallas area during the spring. Those with the least number of Hessian flies were Crawford, USG 3209, Terral LA 482, Terral TV 8558 and Terral LA841.

- Rotate crops. Planting something other than winter wheat would help break the life cycle. Consider oats as an alternative to wheat for grazing. Oats don't host Hessian flies.

- Plant seeds treated with Curiser or Gaucho insecticide.

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