MISSISSIPPI STATE -- Mississippi's cotton growers haven't closed their books on the 1996 crop, but insects clearly will not be the negative factors they were last year.

Many growers' books went in the red during 1995's tobacco budworm invasion prompting Mississippi growers to plant about 28 percent fewer cotton acres in 1996.

Dr. Blake Layton, extension entomologist at Mississippi State University, said insect costs in the state's hill area will be about half the 1995 levels. Delta growers may be looking at two-thirds of last year's control costs.

Layton said Delta growers averaged $76 an acre, and hill growers spent about $118 an acre in 1995. That was the first year hill farmers spent more on insect control than Delta growers.

"Insect populations ebb and flow; 1996 was an ebb year," Layton said. "Tobacco budworms were present, but they weren't as healthy and were fewer in number than last year. Therefore, growers didn't have to treat fields as much."

Commercial availability of Bt cotton, a genetically engineered variety which provides some resistance to tobacco budworms and bollworms, helped some growers this year. Layton said about 42 percent of the state's cotton acreage was Bt cotton.

"Undoubtedly, the Bt acres had an impact on budworm numbers by creating a dilution effect," Layton said. "Growers inherently know where their worst tobacco budworm fields are, so that's where they planted Bt."

Dr. Will McCarty, extension cotton specialist at MSU, said Bt yields are variable.

"In some places, Bt fields had higher yields, and in other fields, non-Bt cotton produced better," McCarty said.

Layton said Bt cotton is more resistant to tobacco budworms than bollworms, and some fields still needed spraying for bollworms.

"Growers sprayed about half the Bt acreage at least once for bollworms," Layton said. "Because of the overall reduced spraying, Bt cotton has increased the need to treat boll weevils and tarnished plant bugs."

Last fall, boll weevil eradication efforts in the state's eastern counties enabled growers to enter winter with a smaller population. Severe cold in parts of the state helped reduce weevil numbers even more.

"Boll weevil numbers have returned, and we are entering winter with high populations," Layton said. "Growers won't get the maximum benefit from Bt cotton until they eradicate the boll weevil."

McCarty said Midsouth cotton acreage will continue to decrease in non-boll weevil eradicated states.

"If the cost of insecticides and licensing fees for Bt cotton remain the same, acreage will come down in Mississippi," McCarty said.

Layton said the jury is still out on the cost difference for growers who paid the licensing fees for Bt cotton to reduce tobacco budworms and bollworms versus those who controlled with insecticides.

"If we had budworm numbers like last year, Bt growers definitely would have had an advantage," Layton said. "Unfortunately, insect populations are very unpredictable."