Published on 02/26/04

Tobacco residue problem solved in Georgia

By Brad Haire
University of Georgia

Some countries say they don't want Georgia tobacco because farmers here use too much of a certain chemical on their crop. But the farmers say they use it to produce high yields and good quality. University of Georgia scientists have worked out a system to make both sides happy.

Farmers cut off the flowers that grow from the tops of maturing tobacco plants. This helps plants concentrate nutrients into becoming larger and heavier, increasing yields and quality.

The suckers

After the flower is removed, however, plants begin to grow little shoots called suckers where the leaves branch off from the stalks. There can be many suckers on one plant. And each can suck nutrients away from the large leaves farmers want to sell.

"If the grower's not able to control suckers, the yield and quality of the tobacco will be severely reduced," says J. Michael Moore, a UGA Extension Service tobacco agronomist in Tifton, Ga.

Moore and other UGA scientists and Extension Service agents in tobacco counties have developed a sucker control system that enables growers to depend less on maleic hydrazide (MH), the systemic growth-regulating chemical international buyers shun.

Another way

They do it by using contact fatty alcohols with a noncontroversial chemical called Prime+.

With this treatment, growers can control sucker growth, Moore said, and produce cured leaf with acceptable MH residue levels. The Georgia growers who use the system will be able to sell their tobacco in world markets.

To control suckers, farmers use contact or systemic chemicals. Contact chemicals run down the stalk, burn newly formed suckers and cause them to dehydrate. The plant doesn't absorb them, and foreign buyers have no problem with them.

Systemic chemicals, however, are absorbed by the plants. They restrain cell division around the suckers to stop their growth. MH is the most common growth-regulating chemical used to do this.

No studies have shown for sure that MH is bad for humans, Moore said. But some countries like Germany don't want to buy some U.S. tobacco because of its high MH levels.

The international target for MH residues on tobacco is 80 parts per million. Most buyers don't want anything higher than this. Georgia tobacco samples have averaged MH levels between 125 ppm to 210 ppm over the past 15 years, he said.

Georgia's warm, humid environment makes suckers more likely to grow. Without the alternative treatment with Prime+, the state's farmers have to use more MH to control them, he said.

As much as 50 percent of Georgia's tobacco ends up overseas, Moore said. It's important for the state's farmers to have access to international markets, especially since they can grow only half as much tobacco as they did in 1998 because of quota reductions by the U.S. government.

Georgia growers will grow about 54 million pounds of flue-cured tobacco in 2004, about 16 percent less than in 2003. They'll start planting it around March 15.

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