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In small grains

Early planting may increase pest pressure THE EARLY BIRD may get the worm, but being early also may attract Hessian flies, greenbugs, Russian wheat aphids, cherry-oat aphids, and other pests in early-seeded small grain.

Probability of insect pest infestations increases in small grain fields that are planted earlier than recommended, warns Texas Extension entomologist Emory Boring. He says delayed planting is one of a number of cultural practices farmers may employ to reduce insect damage potential. Crop rotation, tillage, variety selection and promoting vigorous plant growth also play important roles in pest management.

Boring recommends farmers planting wheat for harvest to seed no earlier than Oct. 1. Farmers who intend to graze wheat should wait until after Sept. 15, he says.

Texas farmers plant wheat on more than 6 million acres each year; they graze about 40 percent of the acreage to some extent and use 30 percent only for forage.

"Delayed planting will help farmers avoid insect problems," Boring says. Beet armyworms pose a significant threat to early-planted wheat and may be especially active this fall, based on summer infestation levels.

Boring says curl mites also may damage fall-seeded wheat.

"We recommend that growers clean up all volunteer wheat before planting, to avoid curl mite damage," he says.

Hessian fly populations, so far, have been confined to central Texas, mostly the Blacklands area. The pest can be devastating to wheat, Boring says.

"Planting later allows wheat farmers to miss at least a part and maybe a whole generation of Hessian flies."

Russian wheat aphid and bird cherry-oat aphids will have less time to establish populations as well.

He says planting too early comes with other downsides. "Farmers do not help themselves a lot by getting a jump on planting dates. Seeding in hot, dry conditions is no advantage. Wheat and other small grains do not perform well until temperatures moderate and moisture is adequate.

"Small grains will not grow well when daytime high temperatures are in the upper 90s. Small grains planted when temperatures are cooler will establish more quickly and grow more vigorously."

Boring says other cultural practices, including variety selection and tillage, also reduce potential for damaging insect pest infestations.

Farmers in areas where the Hessian fly has caused problems may choose resistant varieties of wheat or barley. "Unfortu-nately, the Hessian fly has developed new biotypes that overcome the resistance genes. This has also been a problem with greenbug, although TAM-110 is resistant. In the Panhandle, its area of adaptation, TAM-110 provides effective greenbug control," Boring says.

Tillage plays a significant role in small grain insect control. It not only destroys host plants, but also may bury some insects too deeply for survival. Plowing under stubble reduces populations of Hessian fly and some other pests that remain on or in the stubble.

Reduced tillage offers significant advantages for some grain farmers. "Less tillage leaves more crop residue on the soil surface, reduces soil temperatures, and increases soil moisture," Boring says.

"But some evidence shows that reduced tillage may encourage certain diseases and insects, the wheat curl mite, for instance."

Boring says this mite is a problem especially in the Texas Panhandle, where it survives between crops on volunteer wheat. Winter grain mites and brown wheat mites increase where there is crop residue.

"Other research indicates that reduced tillage decreases aphid numbers. In a reduced tillage program, intensified pest management may be needed to prevent crop losses."

Reducing small grain stubble and controlling volunteer plants and summer weeds will help manage Hessian fly and wheat curl mite.

Boring says crop rotation is particularly useful for managing pests with a limited dispersal range, such as Hessian fly, white grubs, wireworms and winter grain mites.

He says any factor that affects a small grain plant also affects insects and mites that feed on it.

"The healthier, more vigorously growing, and larger the plant, the more pests it can tolerate without significant loss. We've seen this for the greenbug, bird cherry-oat aphid, winter grain mite and Hessian fly."

He says the best pest control strategy is prevention.

"Use good agronomic practices and cultural methods and apply insecticides only when pest populations reach levels that can cause crop losses greater than treatment cost. In season, farmers must inspect fields regularly, twice weekly during critical periods, to make informed pest management decisions."

Pests are active at different times during the small grains growing season - September through June. Consequently, prescribed planting dates, rotation, tillage and other recommended cultural practices will increase the crop's chance of avoiding or surviving insect pest infestations.

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