Call it serendipitous, but at a time when piercing, sucking insects such as aphids, plant bugs and stinkbugs are becoming more of a threat in cotton, Bayer Corp. is introducing a new insecticide formulation that promises to provide more effective and economical control of the pests.

Trimax is a new formulation of Bayer's imidacloprid insecticide that Bayer has registered specifically for use on cotton. Bayer says Trimax will be offered at a significantly lower price than Provado, the company's older imidacloprid product.

“Trimax is a product that has been specifically engineered for cotton with an active ingredient you're familiar with,” said Jimmy Johnson, cotton market manager for Bayer, announcing the launch of Trimax at a cotton consultants meeting sponsored by Bayer.

“The introduction of this new product and our Scout Link program for consultants are two elements of a change in business strategy that Bayer Corp. has been working on for five years,” he noted.

Johnson said surveys and focus groups conducted by Bayer in recent months indicate a distinct shift from caterpillar insects such as bollworms and tobacco budworms to plant bugs and stinkbugs in the amount of insecticide sprays required in cotton.

“One of our surveys shows that 67 percent of U.S. cotton producers made insecticide applications for aphids in 2001,” he noted. “And you have heard from speakers at this meeting that plant bugs and stinkbugs are a growing problem.”

The Food Quality Protection Act, which required reregistration of the organophosphate insecticides, could also reduce the availability of traditional products for plant bugs and stinkbugs. “We need new products to replace those old standbys,” said Johnson.

Imidacloprid, which is also the active ingredient in Gaucho and Admire, was discovered by Bayer in 1985. The first commercially introduced compound of the class of chloronicotinyl insecticides, imidacloprid is the largest-selling insecticide in the world, according to Bayer's Herb Young.

“Imidacloprid is a major player in fruits and vegetables, and that has been the driving force in the costs associated with producing it,” said Young, a field development representative with Bayer.

“Trimax is specifically engineered for cotton and will be priced accordingly — that is for multiple applications in cotton.”

Johnson and Young said the Trimax molecule would offer more than economical control of aphids, plant bugs and stinkbugs, however.

“Trimax has what we're calling 3D technology in that it will provide three dimensions for growers — pest management, improved plant health and enhanced yield,” said Johnson. “Growers will come to look at it differently from other products.”

The active ingredient in Trimax is the only insecticide in the nitroguanidine subclass of chloronicotinyl insecticides with a chloropyridine side chain, said Young. This distinguishing side chain is structurally related to compounds such as nicotinamide and chloronicotinic acid (CNA), which are known as systemic plant resistance inducers.

“This 6-CNA side chain is unique in that it will help plants fight viral or disease effects or better tolerate environmental stress,” said Young. “We have also observed yield increases that were unexplainable — they occurred when no insects were around.”

He said the increases of 16 to 30 percent have happened in numerous trials, but that Bayer researchers have been unable to pinpoint a specific reason for the higher production in fields treated with Trimax compared to those that were not.

Imidacloprid, the Trimax active ingredient, works to bind to acetylcholine receptors in the gaps or synaptic clefts in the nerve cells of target pests. The resulting impairment of the nerve cells causes insects to stop feeding and reproducing before they die.

“If you evaluate it within the first one to two days after application, Trimax may look mediocre,” says Young. “By six days after treatment, it will display activity that is superior to other products.”

He said the water solubility of Trimax enables it to disperse throughout the leaf within 24 hours but not move away from the site of insect feeding.

“This molecule was selected because of its water solubility and that a tremendous amount of material can move through the plant in the first 24 hours,” he said.

Trimax also has translaminar activity, meaning that it can move from the upper surface to the lower surface of the cotton leaf, a key ingredient in its ability to control aphids. “In studies with caged aphids, we have observed 100 percent mortality within 24 hours of the Trimax application to the plant,” said Young.

The feeding inhibition resulting from applications of Trimax may require consultants to evaluate plant bug and stinkbug numbers differently, said Keith Vodrazka, field development representative for Bayer in the Mid-South.

“Live insects may remain in the field, but they will no longer damage the crop,” he said. “That's one of the reasons that evaluating for tarnished plant bugs should include monitoring the square retention of the plants.”

Vodrazka said studies at the University of Arkansas have shown that 90 percent of square loss prior to bloom can be related to insects, primarily tarnished plant bugs and other lygus species. “Thus, retention of those early squares can be one of the most important factors in determining yield.”

Besides square retention, protecting those early squares can increase the earliness of the crop, helping plants avoid stress and exposure to late-season insects, he noted.

Trimax will be priced at around $5 an ounce or about $5 per acre for plant bugs and stinkbugs and about $7.50 per acre for aphids and late-season infestations of plant bugs, said Terry Singley, director of sales for Bayer's southern region.

“Many farmers are making six to nine applications per season for plant bugs or the number of applications they used to make for Heliothis,” he said. “With today's materials and their rates on cotton, growers can't keep that up.

“Trimax will give you three to five days of residual control so that you can reduce that number of applications, and it will provide plant health benefits and increase yields in ways that we're still learning about.”