Blue mold is caused by a fungus-like orgnanism in the downy mildew group. It can be a devastating disease, whether it occurs on transplants or in the field. Symptoms on tobacco transplants begins as yellowish leaf spots that lack distinct margins. (Photo: Kenneth Seebold, UK)

Yellowed blued mold lesions may have a cupped appearance. (Photo: Kenneth Seebold, UK)

A blue-gray downy growth forms on the undersides of blue mold-infected foliage, Numerous spores capable of initiating new infections are produced wthin this downy growth. (Photo: Kenneth Seebold, UK)

These young, yellowed tobacco transplants are loaded with blue mold spores. (Photo: Kenneth Seebold, UK)

Blue mold can be very destructive in a float system, especially when this disease occurs early. (Photo: Kenneth Seebold, UK)