Producers have a new product that helps their tobacco plants help themselves against blue mold in the field. Actigard 50W, manufactured by Syngenta, received a label last August for the treatment of blue mold.

Immune system

Actigard isn't a “cide,” it doesn't kill anything; rather it takes advantage of and activates the plant's natural immune system. “It's a material that actually causes the plant to activate the system within the plant itself,” Alex Csinos, University of Georgia plant pathologist, explained to about 60 growers from North Carolina and Georgia who listened in on a teleconference last month. “It's something like a flu shot. It's important that it be applied prior to the challenge by the pathogen itself. It has to have time to build up an immunity.”

Once in the plant, Actigard activates the proteins that the plant produces to fight disease.

At a rate of a half an ounce per acre in a minimum of 20 gallons of water, Actigard is labeled for use on tobacco when the plants are at least 18 inches tall, says Allison Tally, Syngenta technical brand manager. “Actigard is not a pesticide, it's a plant activator. It protects against blue mold. At the present time, research is under way on the prevention of tobacco mosaic virus and tomato spotted wilt virus using Actigard.”

Paul Shoemaker, North Carolina State University plant pathologist in burley, has worked with Actigard in research and field plots for the past six years. He says coverage is not as important with Actigard as with other products.

Absorbed by plant

“Actigard doesn't need good coverage to work,” Shoemaker says. “With Dithane or Acrobat, you have to have high pressure sprayers and get good coverage. Actigard is absorbed through the leaf and goes throughout the plant, without thorough coverage of the leaf.”

Actigard, which can be applied two times during the growing season, takes about two to five days to activate the plant's natural defenses, which correlates with the protection of blue mold.

“It's important to apply Actigard preventatively,” Tally says. “If a grower hears that the risk of blue mold is high on the advisory, if he'll go ahead and apply Actigard, it would give him the two to five days the material needs to activate the plant's natural defense system.”

In burley, Shoemaker cautions that the use of Actigard can cause yellowing and stunting prior to 18 inches. In flue-cured tobacco, however, researchers haven't had the yellowing problems when applying Actigard.

“If blue mold is in an area prior to when the tobacco is 18 inches tall, the grower should use another product,” Tally says.

Greenhouse work

Research at the university and company level is currently looking at greenhouse use of Actigard. It is currently not labeled for use in the greenhouse, Tally points out.