Knowledge is power.
So, the more a wheat farmer knows about the insect pests that are likely to infest his crop, the better he’ll be able to control them, says Texas AgriLife Extension entomologist Chris Sansone.
Sansone handed out a bit of useful insect knowledge at the recent Big Country Wheat Conference in Abilene, offering identification tips and control options for the usual suspects, including grubs, aphids, greenbugs, Hessian fly, fall armyworm and grasshoppers.
He said white grubs or June bugs follow a three-year life cycle. The second year may be the most damaging. “They feed heavily in the second year,” Sansone said. “Damage in the third year, when it emerges as an adult, is limited.”
He said Texas is home to several species of white grub and they may have different life cycles. “Damage can be severe.”
Gaucho and Cruiser seed treatments “will help but do not offer perfect control,” Sansone said. “Gaucho is the better grub material.”
Barley yellow dwarf (BYD) is a virus carried by an aphid. Gaucho may be a good option for control. “Treatment also may depend on when the aphid moves in. If it comes in late, wheat can tolerate it better.”
Sansone said farmers “can’t spray out BYD. And a few aphids can spread the disease. Seed treatment will help.” It’s a preventive measure because “we can’t tell if aphids are carrying BYD.”
“Greenbugs are always an issue, but we’ve seen fewer the last few years because of seed treatments. Also, Tam 112 has resistance so we recommend it if you have greenbugs.”
Seed treatments go on early, Sansone said, and a lot can happen to a wheat crop from planting to maturity. “So we might not always see a financial advantage (with seed treatments).”
Hessian fly can destroy a promising wheat crop. “They are moving west,” Sansone said.
Resistance may be the best control option, but should be combined with other strategies. “Duster and Coronado are resistant and we know resistance is effective on Hessian fly, but we also know that the fly can change.”
Other control options include area-wide planting delay, seed treatments, rotation (helps a little), crop destruction and alternate crops for grazing. “We can’t rely on just one practice,” Sansone said.
The fly is adaptable, too. “It will wait on a one-inch rain and moderate temperatures to emerge in the fall. Delayed emergence, however, often do not build to high numbers.
“A seed treatment may reduce numbers for the first generation, but resistant varieties are still our best option.”
Sansone expects fall armyworms, “will be an issue this year, so farmers should be aware of their planting schemes. If grazing, late planting is not recommended because you can’t delay grazing.”
Control threshold is 10 to 12 larvae per square foot. Wheat may be at risk as long as 210 days after planting.”So what we do today may not be effective tomorrow. It’s important to know yield goals.”
Grasshoppers should be “stopped at the borders,” Sansone said, before they move into the fields. “They usually come in the spring,” and may move into wheat from rangeland and roadside ditches. Populations had begun to decline in August.
Dimlin is the best control option, Sansone said, “but only on grasshoppers without wings.”
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