Germination and post-germination development of Colletotrichum dematium f. circinans on Allium cepa

Abstract

Spores of Colletotrichum dematium f. circinans were inoculated onto the abaxial epidermis of washed and unwashed pieces of leaf-base tissue taken from the first thru fourth layers of white, yellow and red onions. Washing tissue dramatically improved germination, less than 0.1% for unwashed versus 83% for washed. Germination capacity, and the number of germination types (16) found on washed tissue was not affected by onion bulb color or leaf-base layer inoculated. Spores with one sessile appressorium, type 001, or with one germ tube without an appressorium, type 100, or with one germ tube with an appressorium produced at the tip, type 110, made up approximately 93% of the types for those spores which germinated.