Mounting Forces
July 26, 2010 Most growers in west and south Texas understand the trade off they have with growers in other parts of the Cotton Belt.
Unlike most other cotton growing regions, water is often a scarce commodity. Low moisture levels affect the early season and water scarcity can become a huge problem when it comes time to irrigate.
The flip side of that coin is that the vast majority of Texas growers never see the insect pest pressure that growers in the Mid-South and Southeast contend with annually. But according to at least one entomologist, that scenario has been flipped on its head this year.
West Texas growers were pleased to see unusually heavy spring rains this year, but the added moisture may have been a boost to some uninvited guests.
“We had those heavy spring rains, so we have a lot of these pests building up in the weeds. That’s what’s getting these insect populations going,” says Dr. David Kerns, associate professor and entomologist with the Texas AgriLife Extension Service. From his office in Lubbock, Kerns is charged with keeping an eye on all cotton pests in all corners of the Lone Star State. He says the heavy weed growth that provides shelter for many of cotton’s pests could catch many growers off guard this season.
To compound that problem, the spring rains set planting back just enough to cause problems early in the growing season when cotton is most vulnerable to insect pests, according to Kerns.
“That cotton is not going to mature as quickly. In a normal year, once it matures and cuts out, it’s really not very attractive to most of these pests. And so they’ll just kind of pass over it, and we’ve got enough other crops and things around that they’ll go to those,” he says.
“But as late as this cotton is, it’s going to be attractive in that window where the pests are abundant. So that’s what we’ve got to watch for.”
Lygus Issues
High Plains growers are by no means strangers to the plant bug. According to Kerns, there are almost always a few outbreaks of the pest each year. With the abundance of wild hosts in the form of weeds this year, Texas growers may see an overflow of the pests that Mid-South growers know all too well.
“This year again, because we had so much spring rain, the chances are that we’ll have a lot bigger lygus year than normal,” says Kerns.
The region saw a similar weather pattern in 2007, when both plant bugs and cotton benefited from heavy spring rains. Kerns said growers in the state treated many acres for lygus that year, although the West Texas pests cause significantly less financial damage than do their cousins in the Mid-South.
“They’re not like the ones in the Mid-South. They’re actually mostly the hesperus species, and they’re easier to kill,” says Kerns.
While Mid-South and Southeast growers struggle with lygus lineolaris, better known as the tarnished plant bug, growers in Texas contend with lygus hesperus, or western tarnished plant bug. There is no denying which species is the toughest to handle.
“The Mid-South has a real hard time with resistance, and Arizona does, too. But we don’t have that problem. It’s just a matter of catching them at the right time, because they’re real flighty. We’ll see them come in and the adults will stay, maybe just four or five days, and then they’re gone. Then you have the egg-hatch afterwards. That’s what you’ve got to catch,” says Kerns.
Once again, the spring rains made this growing season an unusual one when it comes to dealing with cotton pests.
“In most years, we don’t see the lygus until later in the season, so most of our damage is on bolls. But years like this, when we have a lot of lygus in the weeds, the weeds will dry down and we tend to see a lot more damage during the early blooming stages. That’s usually more serious than later,” says Kerns. “I suspect we’ll have a bigger lygus year than normal.”
Aside from Lygus, Texas growers have a whole host of other pests to keep an eye on. Many have already felt heavy thrips pressure, and Kerns suspects a heavy aphid season could be under way as well. When aphid populations get high, Kerns says they often tend to flare spider mites. Many growers planting conventional cotton could see bollworm problems as well.
Managing the Problem
Although pests like lygus may be easier to manage in the Texas, the problem still requires some attention. And for growers accustomed to smooth sailing when it comes to insect pests, years like this year can seem overwhelming.
“We can have years where we almost have no pests. Almost none. Last year was one of those years,” says Kerns.
“Then we get years like this one may turn out to be, where we have pretty severe pest problems. They don’t seem like they’re ever as severe as say the Mid-South. But when you’re talking about guys who aren’t used to dealing with any pests who suddenly have to deal with three to four a year, then it seems really severe to them.”
There is no preventative work that can be effective, he says. The best course of action is to stay vigilant, and to rely on the better judgment of available consultants.
“Luckily we’ve got a lot of good consultants out here and they’ll pick them up. The growers who don’t use consultants, they tend to watch what their neighbors who have consultants are doing. They see that if their neighbors are running into something, then they’ll get out and check it out, too. It’s consulting by observation on their part,” says Kerns.
Growers are typically reluctant to spend money on the back end of the growing season ― often a by-product of the high front-end costs that growers have recently been subjected to through technology fees on bags of seed. While that strategy may seem tempting, if not necessary, years with heavy insect pressure can expose an unprotected field.
“Nobody likes to spend money late in the season. Unfortunately that’s when we tend to have most of our pests. Other than thrips, they all tend to appear late in the season,” says Kerns.
“Unfortunately a lot of these guys, particularly if they’ve got aphids or spider mites, they’ll sit on them and sit on them and then they usually spray too late. These are the guys who don’t have consultants, they’ll wait and wait and spray too late and I think they suffer a little bit where they didn’t have to.”
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