Farmers who invest a little extra time and perhaps a few dollars to head off insect and disease problems may add as much as 10 to 20 bushels to yields and significantly more in forage production for those who use wheat for grazing.
At the least, follow a sound integrated pest management strategy, says Texas Extension Entomologist Chris Sansone, San Angelo.
Sansone says wheat producers need to watch out for several insect pests, including Hessian fly, greenbug and possibly fall armyworm. Less common but still capable of causing trouble is the wheat curl mite, a pest that transmits two virus diseases, primarily in the High Plains and Rolling Plains wheat production regions of Texas.
“One important aspect of implementing an IPM program is developing a strategy for managing a crop, including pest control,” Sansone says.
The tactics may be different depending on the use of the crop. “For instance, some farmers who raise a dual purpose wheat crop have asked about delaying seeding wheat to avoid potential damage from fall armyworm, since conditions heading into late summer appear favorable for infestations.
“The easy answer is, no, don't delay planting,” Sansone says. “The value of early planting to assure early grazing outweighs the concern for infestation,” he says. “Farmers should scout the crop and be prepared to spray if necessary.”
For growers in West Central Texas and the Rolling Plains, Hessian fly and greenbug also pose early season threats. “We've seen Hessian fly in West Central Texas for about eight years,” he says. “Producers in Texas east of I-35 have dealt with the pest a little longer. We have to learn to manage it.”
Sansone says farmers who use wheat for grazing are most vulnerable. “If grazing is their primary goal and they are not interested in harvest, they might consider another grain,” Sansone says. “Oats, rye and triticale are not susceptible to Hessian fly injury.”
He says if growers do count on forage and grain, their next step is to look for resistant varieties.
“In this case the first consideration for variety selection should be forage production,” he says. “Grain yield would be the second factor. And Hessian fly resistance would be third.”
He says tolerant variety choices for Texas producers are limited and becoming more so because resistance breaks down as the fly develops new races. The old Pioneer varieties 2145, 2157 and 2180 still offer some tolerance in certain areas. “Coronado, an AgriPro selection, is the dominant choice,” he says. “Also, TAM 400 (distributed by AgriPro) has Hessian fly resistance. All these have strengths and weaknesses. The biggest shortcoming is susceptibility to rust.”
If growers can't find a variety with resistance that fits their agronomic needs, treated seed is the next best bet. “Gaucho or Cruiser seed treatments offer some protection,” Sansone says. “We've had more experience with Gaucho.”
He says treated seed provides benefits for both Hessian fly and greenbug. “With Hessian fly, treated seed will minimize the impact of the first two generations.”
Untreated Hessian fly infestations may result in no forage and no grain. “Treatment allows a grower to make a crop,” Sansone says. “In some cases, infestations have been so severe that untreated fields had no grazing left by January and no grain harvest. With favorable weather and a good wheat year, treatment can mean from a 10- to 20-bushel increase in grain production and considerably more in forage. One trial in Abilene resulted in a 10,000-pound forage gain with treated seed due to control of greenbugs.”
The treatment can be “very economical,” Sansone says.
Growers who do not graze wheat can delay planting and avoid the Hessian fly. “If we plant after Nov. 1 in West Central Texas, we can avoid damage.”
Sansone says greenbug infestation may be a factor this year, considering average or better than average late summer moisture, which left a lot of weed hosts for the insects. “As those hosts begin to play out greenbugs move into wheat.”
Scout and spray
He recommends producers be prepared to scout and spray. “We can't afford to lose a stand with wheat for grazing. As soon as it's up to a stand, start checking for greenbug infestation and make certain populations don't reach damaging levels.”
Insecticide applications will knock populations back, he says. “In the pat few years, growers have needed from one to three applications for greenbug control. We have a host of products available and it's an economical decision to spray, especially if growers want to graze the wheat,” he says.
Sansone says Rolling Plains wheat producers also should be aware of the wheat curl mite, which transmits two diseases, the wheat streak mosaic virus and the High Plains virus. “Symptoms are similar. We have no chemical treatment for the pest but growers should keep fields relatively clean prior to planting. About two or three weeks before planting, make certain to kill any volunteer wheat. That also helps with reducing greenbug and Hessian fly populations. Usually one application of Roundup will take care of volunteer wheat.”
Sansone says the pests also use some weeds but the best host is volunteer wheat. “We can't do much about treating all the ditch banks, anyway, but we can take care of volunteer wheat,” he says.
Sansone says rotation offers little advantage for reducing insect pest populations. “They move too much. Rotation can play a more important role with prevention of soil-borne diseases.”
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