Investing just under $10 per acre to control thrips may provide farmers some cheap insurance in irrigated cotton, even with low prices and rising production costs.
"This is not a place to cut corners," says Jim Leser, Extension entomologist at the Texas Research and Extension Center in Lubbock.
Thrips, he says, are tied with boll weevils as the insects requiring pesticide applications on the most acreage in Texas. “Farmers often underestimate the damage thrips cause," he says. “It's not just cosmetic.”
Leser says farmers can easily justify treating thrips in irrigated cotton. For one thing, thrips are ubiquitous, moving into cotton nearly every year from drying wheat across the state.
“It takes very little wheat to develop thrips populations that move into cotton,” he says. “And the more wheat in an area, the more thrips we'll see.”
Infestation is particularly heavy when wheat dries down at the same time cotton begins to square.
Leser says farmers who irrigate can’t risk waiting until thrips appear to initiate treatment, although foliar sprays will control them.
He recommends Temik application at planting as an economical preventive measure.
“In irrigated cotton, test data over a number of years, indicate a 21 percent to 22 percent yield increase with Temik under the row. At recommended rates, that’s a $9 per acre treatment.”
At the least, he says, farmers will save at 50 pounds of cotton for a $10 investment.
Farmers who delay treatment to prevent front-loading expenses run the risk of missing early infestations and losing yield potential before they see the pest. “Cotton does not outgrow thrips damage,” he says.
“It makes sense for a cotton grower to apply Temik and then concentrate on other production practices.
“In this economic climate farmers need to get the biggest bang for their buck, so thrips control is important.”
Farmers who are trimming costs may justify lower seeding rates, less fertilizer, fewer irrigation applications and less tillage. “But a 21 percent to 22 percent yield advantage offers too much advantage to ignore.”
Leser says other treatment options may be cheaper but provide less return on the investment.
“And the problem with foliar application is making certain it goes out on time. Farmers can band a foliar insecticide on 10-inch swaths for as little as 25 cents to 30 cents per acre, if they piggyback the treatment onto other field operations. If they make a trip just to treat thrips, they'll spend $3 to $4 per acre and may need a second application.”
He says a foliar automatic treatment, applied when 65 percent of the cotton has emerged, may be another option, but a second application still could be necessary. “Another problem with foliar treatments is that control does not last long enough. But sometimes Temik doesn’t persist long enough either.”
Leser says foliar applications last only a few days. Temik usually provides four weeks of control.
For foliar applications, Leser says growers should initiate treatment at a 65 percent stand if they detect one thrips per plant from no true leaves through one true leaf. At the two-true leaf stage, threshold increases to two thrips per plant and rises to three at three-leaf on up to five at the five-leaf stage.
After five leaves, the cotton should be squaring and treatment will no longer be necessary.
“If growers take that approach, they can come close to the protection they get from Temik. But the costs will be less certain. A second foliar application will bring them close to the 21 percent yield advantage, but it still seems reasonable to use the preventive treatment and not worry about the timing. Timing a foliar application for thrips is absolutely critical.”
Farmers also may opt for seed treatments for thrips control, but Leser says the jury is still out on even the best ones.
Orthene, he says, has been around for a long time and may be applied in the planter box or at delinting. “Most farmers will not fool with the planter box treatment because of the odor and aggravation,” he says. “And they get only about three weeks of control. That’s not enough by about one week.”
Also, the best yield increase growers expect from Orthene will be half that of Temik. “Farmers may save money up front but the net is not as good,” Leser says.
Gaucho has shown good results in other parts of the Cotton Belt but is weak on western flower thrips, the dominant thrips species in Texas and the Texas High Plains.
“It’s not a good choice here,” Leser says. “It does control aphids, however and has shown promise as an aphid material in south Texas.”
Adage may offer protection similar to Temik, but tests are inconclusive, Leser says. “Cost is about the same as for Temik, and some tests across the Cotton Belt indicate it competes successfully with Temik. Other tests indicate it does not. It also may be weak on western flower thrips.
“I tell growers that the jury is still out and to test Adage on limited acreage to see how it compares.”
Leser says seed treatments offer advantages. “It would be easier and less toxic than Temik. And anytime a farmer can simplify an operation he will do it, if it doesn't cost more.”
Until more data becomes available, however, Leser says, “Temik is still the Cadillac treatment for thrips control in irrigated cotton.”
Farmers may want to drive a less expensive vehicle in dryland cotton, however.
“We have two problems with up-front expenses in dryland production,” Leser says “No. 1, yield potential will be way down so the percentage increase will make less of a difference. No. 2, farmers want to minimize front-end expenses as much as possible because they could lose the entire crop to hail or July drought.
“July rainfall plays a critical role in dryland cotton. And with a Temik treatment, we get the same increase in early square retention we get in irrigated acreage. But with moisture limitations later in the season, the plant overcompensates and yields fall. It’s worse than if we had done nothing. Temik seems to set the plant up to fail and we often lose money on dryland Temik applications.”
Leser prefers a less aggressive approach to thrips control in dryland acreage. Seed treatment, he says, may be a better option. “For a small investment, if we get rain, we can still make a crop and provide some protection from thrips, but we don't set up the plant to fail in drought.”
Leser says most dryland cotton farmers prefer to make a boll and then protect it. “But we have to make the boll first.”
He says banded foliar spray provides another option. “Foliar treatments will be less timely but could limit damage and increase yield potential. Foliar applications, with a ground rig, could add $7 per acre in lint,” he says. “We can apply insecticides for less than $4 per acre if we combine treatment with other operations. Again, we can get as low as 25 cents to 30 cents per acre for thrips control with piggyback applications."
Leser says farmers may base foliar applications on automatic treatment when a certain percentage of the stand is emerged or on scouting to detect first signs of damage. Either approach, he says, should result in a yield increase.
He says cost for managing thrips depends on how long the pests move from other hosts into cotton.
“Thrips control is extremely important for Texas cotton farmers,” Leser says.
Protecting irrigated cotton against thrips damage with an in-furrow insecticide may add 21 percent to 22 percent to lint yield, says Jim Leser, Texas Extension entomologist.