Published on 07/31/03

Bug gang strikes Georgia cotton crop

By Brad Haire
University of Georgia

There’s a destructive gang running loose in Georgia. It wants to do only two things and has taken an opportunity to drastically increase its numbers in recent years. In its wake, it threatens to suck some profit out of a major Georgia commodity.

Individual members of the gang probably don’t know they’re in a gang. But collectively they’ve gotten the attention of Georgia cotton farmers, says Phillip Roberts, entomologist with the University of Georgia College of Agricultural and Environmental Sciences.

They have complex scientific names. But on the street, or in the field, gang members use aliases like stink bug, tarnished plant bug and leaf-footed bug.

“And all they want to do is eat and reproduce,” Roberts said.

Gang leader

The gang’s ring leader is the stink bug. Common across Georgia and around homes, the stink bug, along with other gang members, really likes the taste of cotton bolls, the fruit-like part of the plant that produces lint.

A hungry stink bug pierces a boll with its needle-like beak and injects a digestive enzyme to soften the tissue inside. It then sucks the tissue out for food.

“In addition to the outside boll damage, the hole it creates allows organisms to enter the boll and cause rot,” he said. This reduces the quality and yield of the cotton from that boll, if it is able to produce cotton after the attack.

Georgia’s cotton plants begin to make these bolls around mid- June. About 75 percent of the cotton now is setting bolls.

New problem

In the past, this gang wasn’t much of a concern to farmers or entomologists. It was controlled when farmers sprayed pesticides on their cotton to kill other bugs and worms. (Tobacco budworms and corn earworms cause the most economic damage to cotton. Left unchecked, they can eat a field down to nothing.)

In the 1980s and early-90s, Georgia farmers had to spray their cotton for worms and bugs as much as 16 times throughout the six- month growing season, Roberts said. And the chemical they sprayed killed most all bugs, including all members of the boll- eating gang.

Due to new technology, however, farmers don’t have to spray pesticides nearly as much anymore.

In the mid-90s, farmers began planting a new kind of cotton, developed to produce an insecticidal toxin created by a common bacteria, Bacillus thuringiensis. When worms eat the leaves of this Bt cotton, they die without causing any more damage to the plant.

Most Georgia farmers now only spray about twice for bugs or worms each growing season. This has saved farmers money and time and has been better for the environment in and around cotton fields, Roberts said.

But now that farmers spray less pesticide in their fields, members of the boll-eating gang have moved in for an easy cotton boll meal. And their numbers are on the rise.

The real damage from this gang will not be known until harvest begins in September and October, Roberts said.

Farmers and cotton scouts should keep an eye out for boll damage and the members of the boll-eating gang right now, Roberts says. If too many gang members show up, farmers should spray before they get out of hand and cause real damage to the crop.

Brad Haire is the former news editor with the University of Georgia College of Agricultural and Environmental Sciences.