Cotton Links


Early Management Keeps
Cotton Healthy

By Carroll Smith
Senior Writer

Undermining threats to vulnerable seedling cotton – thrips, nematodes and spider mites – and applying residual herbicides jump to the top of the list for Mid-South and Southeast cotton producers during this time of the year.

North Carolina crop consultant Danny Pierce warns cotton producers in his area that thrips are worse than they used to be and are difficult to control once they infest young cotton. Although nothing works perfectly, he says the best treatment he has seen to control thrips – if you don’t have nematodes – is a seed treatment and three pounds of Temik. If nematodes are present, then raise the rate of Temik.

“Farmers here begin to get into nematode trouble about the third year after planting cotton behind cotton,” Pierce notes.

Slow-Growing And Susceptible

Francis Reay-Jones, an Extension entomologist with Clemson University, believes that thrips are the most serious early season insect problem because they feed on the leaves and terminals of seedling plants, which tends to stunt plant growth as well as delay maturity.

“When the seedlings are in that young stage, the terminal bud grows at a slow rate,” he says. “The plants are very susceptible to feeding by thrips. Once the plants reach the three- to four-leaf stage, they grow more quickly so they can withstand more injury. The early stages, however, are critical.”

Preventative treatment for thrips is tied to control or suppression of nematodes, according to Jeremy Greene, Research/Extension cotton entomologist also with Clemson.

Preventative Insecticides

Greene divides cotton producers who use some form of preventative insecticide for thrips and nematodes into five different groups.

“Some apply Temik in-furrow, which gives very good control of thrips and good suppression of nematodes,” he says. “Others use seed treatments that also have insecticidal and nematicidal properties. A third group uses Temik in-furrow and a seed treatment.

“Although it’s expensive, we had a plot demonstration replicated in a grower’s field last year in which we had the seed treatment, then the seed treatment plus Temik under conditions of moderate-to-heavy pressure from nematodes and light-to-moderate pressure from thrips,” Greene says. “The seed treatment plus Temik showed a significant increase in yield over the seed treatment alone, which more than paid for the combination.”

However, Greene adds that they have also looked at combinations of Temik and seed treatments under conditions of moderate-to-heavy pressure from both nematodes and thrips where Temik alone looked much better than the seed treatments and as good as or better than the combination, indicating that Temik alone was the best option.

“This variability makes it extremely difficult to recommend one application strategy,” he says. “We can say that nematodes are really the deciding factor on what to use.”

Another group, according to Greene, uses a true fumigant nematicide, such as Telone, for severe nematode problems, followed by a material for preventative thrips control. Occasionally, he says, a farmer will not use any type of preventative control for thrips, but will make about three applications of Orthene from the cotyledon stage through the four- to five-leaf stage. Greene doesn’t recommend this approach because “thrips can inundate a field and be there for a long time while the cotton is in the seedling stage.”

Early Season Weed Control

Pierce, the North Carolina consultant, says in addition to thrips and nematode control, cotton producers in his area need to use a pre-plant incorporated or pre-emergence herbicide to control glyphosate-resistant pigweed.

“If the herbicide application is going out behind the planter, they typically use Cotoran, Direx or Reflex,” he says. “Reflex generally works best for us.”

Louisiana crop consultant Roger Carter agrees that weed control should be of primary concern.

“Farmers who have yet to apply a grass and pigweed residual herbicide, such as Dual II or its equivalent, should do so by the fourth true leaf,” Carter says. “The necessary applications of glyphosate for Roundup Ready cotton should also be made.

“Most farmers are opting to add Staple LX to the first or second application of over-the-top glyphosate to control weeds on which glyphosate is less effective – teaweed, Sesbania, morningglory, etc. Staple LX also has some pre-emerge activity on many weed species and can extend residual control if two applications of the lighter rates are used back to back.”

The Louisiana consultant notes that Envoke is another option for over-the-top herbicide applications once cotton passes the fourth true leaf.

“This herbicide is weak on teaweed, but offers superior morningglory control,” he says.

Clay Despain, who consults in Poinsett County, Ark., says more and more cotton producers in his area are using residual herbicides to control two of their most troublesome weeds – horseweed and Palmer pigweed. They are also trying something new this year – mixing First Shot in with a dicamba and glyphosate burndown to get added control of henbit, which seems to be a host for spider mites.

“If henbit is still green at planting, you could have spider mites on seed-ling cotton,” Despain says. “Spider mites on seedling cotton are nothing new when it comes to borders or hot spots, but they seem to be getting worse in the past few years.

“With that being said, we want our fields to be as clean as possible when we plant,” he says. “That’s why we are going with a two-shot burndown program to clean up the field as early as we can, then come back in and apply Gramoxone and Direx or Gramoxone and Reflex pre-emerge.”

No matter what the situation, getting off to a good start is always advantageous. And, as Roger Carter says, “If cotton is treated properly in the first month of production, then it responds better to necessary inputs the rest of the year.”

Contact Smith at (901) 767-4020 / csmith@onegrower.com.

And Don’t Forget...

In late May, nitrogen (N) also should be of concern as cotton approaches the eighth to tenth node.

With economics dictating the need to reduce inputs when the opportunity arises, it is almost imperative that farmers apply variable rates of N to better utilize their input dollars. Reducing unnecessary N on the rankest growing areas of cotton fields lessens the need for mepiquat chloride applications and decreases insect hot spots.

Checking nozzles on various spray units is also critical for applications that will be made throughout the rest of the year.

Insecticides should be applied using cone, twinjet or, at the very least, extended range flat fan tips. No drift control type tips should be used with any cotton insecticides. Most herbicides work best when using the extended range flat fan tips, but care should be taken with drift to susceptible crops.

Of course, proper pressure should be used with any pesticide application. – Roger Carter, Agricultural Management Services, Inc., Clayton, La.

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