To gamble or not: Some prefer to not roll dice over lygus

It's that time of the year again when San Joaquin Valley cotton growers eye the foothills, scrutinize their neighbor's cropping patterns and wonder what's going to happen with lygus and other plant bugs this season. Even though researchers have made significant progress in their ability to predict the severity of an infestation, it is still an inexact science at best.

“You just never know for sure what's going to happen,” says Gary Robertson, Pest Control Adviser for Helena Chemical in Los Banos, Calif. “Because we're so close to the foothills and because we've got a lot of alfalfa in this area, we're prone to have problems with lygus in cotton. The first question is how bad is it going to be? That one is difficult to answer with a lot of certainty. The second, perhaps more important question for the grower, is what am I going to do about it?”

Basically, there are two options. A grower can invest the money, take a preventative approach or gamble on a wait-and-see strategy. If lygus do indeed materialize as a significant problem, the latter strategy can end up costing the grower much more than he would have spent if he had invested in protection up front. On the other hand, if lygus numbers are low, the grower may save money. For some it's a difficult choice. For others, the only safe bet is not to roll the dice.

For Antone Giannone, a grower near Los Banos, Calif., it's an easy decision.

‘Worth investment’

“For me it's worth the investment to know that my cotton is protected,” he says. “I sidedress Temik just before the first irrigation, and it just makes life a lot more simple and less worrisome for a number of reasons.”

In addition to knowing his cotton is protected, Giannone says not having to rely on foliar applications to control lygus is a big relief. “First of all, a lot of my ground that I farm is close to town, and I don't want to use an aerial applicator if I can avoid it,” he says. “Secondly, when you start relying on the harsher foliar materials to control lygus you run the risk of creating all sorts of secondary pest problems because you kill all the beneficials. That can get expensive in a hurry.”

Giannone sidedresses 14 pounds of aldicarb per acre, and even though it's a substantial investment, he feels that it is one well worth the expense. “You've got to spend money to make money,” he says. “I think it's a good program even in years when lygus don't show up in huge numbers. Even though we have established threshold numbers for lygus that supposedly tell us when to pull the trigger on a foliar application, I think those sub-threshold levels of lygus are hurting us more than we give them credit for.”

Protecting the bottom crop is particularly important, according to Robertson. “If you get a bunch of lygus that hit when you're trying to set that bottom crop, you're probably in big trouble if you don't have it protected,” he says. “You've got to manage that plant from the bottom to the top and the bottom bolls are what make the most money.”

Cultural steps

Whether a grower chooses to go with a preventive approach or a wait-and-see strategy, there are certain cultural practices that can reduce the impact of lygus on cotton in either program. Manipulating the dynamics of lygus movement by strip-cutting alfalfa is one of the primary cultural methods of minimizing damage in nearby cotton fields.

“There are a lot of guys in this area that have been trying this in the past few years, and I think it's helped,” Robertson says. “Lygus actually prefer alfalfa to cotton anyway, so if you can avoid destroying their entire habitat by cutting the entire field at the same time you can help minimize the influx into cotton.”

Considerable time and effort has been invested in the dynamics of lygus movement among different crops in the valley and out of the adjacent foothills into the valley floor during the spring. University of California researchers are looking at the broad picture in an effort to develop better site-specific integrated pest management strategies. In particular, technologies such as Geographic Information Systems and satellite photography are helping researchers track lygus migrations throughout the mosaic of Valley crops. Combined with ground verification of lygus infestations, this approach has improved researchers' ability to make predictions about future infestations and given growers a little bit better yardstick to measure their decision on whether a preventative or wait-and-see approach is the better option. Ultimately, however, it's a matter of how comfortable a grower feels about rolling the dice.

“I intend to make a good crop of cotton every year that I plant it, so I'm going to do what I know will work,” Giannone says. “Besides that, I enjoy sleeping at night.”

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