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Posted 15 April 2008. PMN Crop News.

Watch for Blue Mold in Tobacco Float Beds

University of Tennessee Institute of Agriculture.

Knoxville, Tennessee (April 1, 2008)--Tobacco growers should be on the alert for symptoms of blue mold in their plant beds. A plant pathologist with University of Tennessee Extension, Steve Bost, says the plant disease got off to an early start with a discovery in a northern Florida plant bed on March 12.


Several weather systems have occurred since then that may have transported spores to the Tennessee area. Bost says if blue mold is found at this stage of the season, it could be disastrous for growers. "Entire beds could be lost," he explains. "If infected plants are set in the field, it could mean an entire season of battling the disease - a battle made more difficult by the fact that one of the fungicides needed for effective control is in low supply."

Bost says growers should not buy plants from Florida and Georgia, as they carry a high risk of infection. All plant beds in Tennessee should be sprayed with protective fungicides labeled for this use, if the seedlings have dime-sized or larger leaves. The applications should be repeated each week.

"Check your beds every day for symptoms," Bost recommends. "If you see suspicious symptoms, notify your county UT Extension agent and get a second opinion. If blue mold is confirmed, agents will warn area growers to follow spray programs."

"The success of the warning depends entirely on your finding the disease. Watch your plant beds!" Bost stresses.

Blue mold in plant beds can be difficult to recognize because of the lack of yellow spots found on field plants. Blue mold in beds can be mistaken for nutrient deficiency. Bed plants may simply have a pale or mottled yellow appearance. A grayish spore coating may or may not be seen on the undersides of the leaves. The stem and leaf midrib may show a bluish to reddish color, due to systemic infection.

For more information contact your county UT Extension agent.

Steve Bost