Blue mold found on east Kentucky tobacco

Recently, blue mold was found on tobacco in Clark and Montgomery counties in Kentucky (USA).

Growers located in the vicinity and east of the initial find, especially those with young plants, should scout their fields for the disease and apply a preventative fungicide, said Kenny Seebold, Extension plant pathologist in the University of Kentucky College of Agriculture.

The disease was present on nearly 100 percent of tobacco in two fields totaling about 15 acres, and significant levels of the disease were present in nearby fields. The disease likely arrived over the July 4 weekend. The find is significant because the disease is widespread in the infected areas, and recent weather conditions were favorable for the disease to spread.

"In many years, blue mold shows up in an isolated case or the weather is too dry to promote rapid spread," Seebold said. "However, the cooler-than-normal temperatures we have had were ideal for the disease to spread."

In addition, many growers this year delayed planting because of the wet spring, which means there are still significant amounts of young plants. Blue mold is more likely to damage these plants. In a normal year, much of the state's tobacco is topped by now and not as susceptible to blue mold.

Growers near the infection site and eastward should apply a fungicide to contain and prevent the disease. Quadris or a combination of a mancozeb fungicide with a fungicide containing dimethomorph are the most effective against blue mold.

"When applying fungicides for control of blue mold, good coverage is critical for getting adequate control of disease," he said. "This means using an appropriate application volume and drop nozzles to get fungicide materials down into the lower plant canopy."
Those who have already topped their tobacco or will do so in the next few days may not need a fungicide application, but they need to have good sucker control because blue mold is attracted to suckers.

Growers west of Clark County have a low risk for disease development so spraying is not as critical, but some may want to apply a fungicide to prevent blue mold's onset. These farmers should look for the disease and be prepared to spray if favorable disease movement conditions are predicted or if blue mold is found in your area.