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Scouting Is Critical In
Insect Management

By Tommy Horton
Editor

 

Where are we today in insect management? It depends on what part of the Cotton Belt a producer farms. To gain a broader view of how each production region is faring, Cotton Farming contacted an entomologist in each major area to gain a perspective on current and future trends.

Here’s a region-by-region look at the situation.

Mid-South

Plant bugs and spider mites are easily the major insect pests in this five-state region, and the situation isn’t likely to change anytime soon.

“Most people will tell you that the plant bug is our No. 1 pest, but the problem varies across the Mid-South,” says Tennessee Extension entomologist Scott Stewart, who is based in Jackson.

“In the Delta areas of Mississippi, Louisiana and Arkansas, the infestations were relatively high. That’s where you’re finding multiple spray applications, and that is also where you’ll find insecticide resistance developing.”

That resistance is probably due to having higher plant bug pressure, and thus producers spray more in those areas. How many more times do they spray? In some parts of the central and southern Delta, Stewart says it wasn’t uncommon for a farmer to spray 10 or 15 times last year in the battle against plant bugs.

While this pest has wreaked havoc in the Delta environments, it isn’t as big a problem in other areas, such as the hilly terrain of West Tennessee.

“Don’t get me wrong,” says Stewart. “The plant bug is alive and well in our region, but not to the levels you’ll see in other parts of the Mid-South, and populations in all areas vary considerably from year to year.”

According to Stewart, the plant bug infestations are an alarming trend for many reasons. The increased recurrence of tarnished plant bug appears to be robbing some of the value of the boll weevil eradication program.

The pest continues to cause damage in key cotton areas of the Mid-South that can ill afford to sustain that kind of problem.

“It certainly would’ve been better if this pest had not developed into such a problem,” says Stewart. “We’re still trying to develop some control methods that are not entirely based on insecticides.”

Those strategies include managing weed hosts, alternating insecticide choices, proper selection of varieties, managing for earliness and other IPM tactics. An ongoing regional effort has also been underway for several years to define further when insecticides should be applied to this pest.

Still, even with that kind of overall strategy, it isn’t easy coming up with an effective plan for battling plant bugs. As Stewart likes to say, “there aren’t a lot of magic bullets out there right now for this pest.”

As if the plant bug problem weren’t enough, Stewart says spider mites are emerging as the clear No. 2 pest in the region.

Southeast

Even after a two-year drought, the Southeast will encounter bollworms and stinkbugs again this year.

Phil Roberts, Georgia Extension entomologist in Tifton, says he’s anticipating a normal year for pests in the region.

And what exactly does “normal” mean?

Corn earworm (also known as bollworm) and stinkbugs are likely to be the two top insect pests. But these culprits actually weren’t as troublesome in 2006 and 2007 due, in part, to drought conditions observed. Winter and early spring rainfall levels probably mean that trend will change.

“There’s no doubt that the drought conditions reduced alternate host plants on which populations build for these two major insects,” says Roberts. “Although we cannot predict the future, this is a different year, and I expect levels to be higher.”

Another factor in the Southeast – and specifically Georgia – is increased corn acreage that previously was in cotton. Because both stinkbugs and corn earworm reproduce in corn, populations may migrate from corn acreage into cotton. That trend won’t be as significant in 2008. Georgia, for example, didn’t make a big switch into corn as much as other regions of the Cotton Belt.

Roberts also believes producers in his region should be judicious in their use of insecticides. Applications should only be made when action or economic thresholds for pests have been met.

And he’s a big proponent of effective integrated pest management strategies.

“These are things that producers need to be aware of as they implement their best practices,” he says.

Roberts says aggressive scouting also must remain a priority for producers, no matter how low the insect levels were in 2006 and 2007.

The remarkable fact for Georgia producers last year is how they produced a cotton crop that averaged 800 bales an acre during a drought.

“We must have done something right in our management practices,” he adds.


Southwest

Fleahoppers and lygus are the main insect pests in this region. But neither has reached serious infestation levels.

Fortunately, these pests are nowhere near the problem in this region as compared to other areas of the country. Texas A&M University entomologist Megha Parajulee is based in Lubbock and says they aren’t close to being an economic threat to crop production.

Parajulee says several factors contribute to this decreased insect threat – a cotton monoculture, shorter growing season and fewer pest host environments.

“One of the things that prevents lygus from becoming more serious is that we have a lot of roadside weed habitat hosts, and that prevents this pest from moving into cotton,” he says.

Fleahoppers, by default, have become more of an economic pest but nowhere near enough to be characterized as a serious problem. Parajulee says it’s fortunate that Southwest cotton production doesn’t face the same insect problems of other regions.

“With so much attention being put on cotton production in Texas, it’s good that we don’t have a wide insect pest spectrum,” he says. “If we did, we’d be in trouble.”

Simply put, Texas doesn’t have enough wild host environments to help increase major cotton insect populations. Still, that doesn’t mean producers in this region can become complacent and never worry about serious insect outbreaks.

Texas cotton acreage is 55 percent irrigated and 45 percent dryland. According to Parajulee, a Temik or seed treatment is recommended to deal with early-season thrips problems.

Surprisingly, this region has something in common with the Southeast and Mid-South. Last year, there were several outbreaks of spider mites. It appears that this insect could become the emerging pest of the future.

The trend, however, hasn’t reached the serious stage.


West

Although acreage has decreased in this region, cotton producers aren’t taking anything for granted.

Peter Ellsworth, research & Extension entomologist at the University of Arizona’s Maricopa Agricultural Center, says the same three major pests – pink bollworm, whitefly and lygus – remain at the top of the list for most Western producers.

Fortunately, insect pressure for the past two years was at a historic low level in the region. In Arizona, a pink bollworm eradication program is underway, and the results have been promising.

“In most areas, pink bollworm populations were lowered significantly,” says Ellsworth. “So, the eradication is working quite well. If the progress can continue, I think this is a pest of the past for Arizona.”

Although there was more winter moisture in the West this past winter, Ellsworth echoes the comments of other entomologists across the Belt when he warns producers not to become too comfortable in their various insect management programs.

With the added moisture, insect levels could return to normal levels and pose a threat. Those populations also may develop because of more host environments.

Contact Tommy Horton at thorton@onegrower.com or (901) 767-4020.


Cotton Insect Facts

• Losses to arthropod pests reduced yields by 3.6 percent in 2007.
• Pest losses were higher in Southeast states where drought also caused heavy losses.
• Bollworm/budworm complex remained the top-ranked pest, reducing yields by 0.91 percent, a slight increase over 2006.
• Lygus were second at 0.68 percent.
• Thrips were third at 0.57 percent.
• Fleahoppers were fourth at 0.47 percent.
• Aphids were fifth at 0.32 percent.
• Total cost and loss for arthropods in 2007 was $877 million.
• Losses below 5 percent reflect contribution technology has made to managing pest complexes.

Source: Mississippi State University

 


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