Blue mold found on tobacco transplants in central Kentucky greenhouse
Kentucky has been hit with the season's first instances of blue mold, according to a report by the University of Kentucky’s Department of Plant Pathology.
Blue mold was found Friday, June 1 on tobacco seedlings in a greenhouse in Fayette County. Active sporulation was observed in a small portion of the transplant facility, and was apparently in an early stage of development. At the moment, the source of the blue mold outbreak has not been determined.
Blue mold is a systemic disease borne by a fungus that can easily cause entire crops to be wiped out.
Measures were taken to contain the outbreak and limit spread of the pathogen, Peronospora tabacina. The entire greenhouse was sealed to avoid the further release of blue mold into the outside environment and to permit heat to destroy infected plants and those that were potentially infected. All plants with sporulating lesions were placed in clear plastic bags that were sealed and left inside the greenhouse as an additional precaution.
UK tobacco officials say that it is advisable to make sure that any tobacco in float beds (outdoor and greenhouse) are treated with Dithane DF to protect against blue mold. This is especially important for tobacco being grown near Fayette County, but would also be a good measure of insurance for the rest of the region.
The recommended rate of Dithane DF is 0.5 lb/100 gal of finished spray (or 1 teaspoon of product per gallon). Since Dithane is a protectant, it needs to be in place prior to the arrival of inoculum for best effect, and this means preventive applications are the key for success. Apply as a fine spray to achieve thorough coverage.
The risk at this time to plants in the field is low due to the prevailing hot and dry weather. However, ia period of cool and rainy conditions would mean plants should be treated with Dithane DF (1.5-2 lb/A) + Acrobat 50 WP (2-8 oz/A), Quadris (6-12 fl oz/A), or Actigard (0.5 oz/A).
Plants need to be at least 18 inches tall before receiving an application of Actigard, and the material should be applied 3-5 days before infection for the product to work effectively.