|Johnson, David - MICHIGAN STATE UNIVERSITY|
Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 10, 1998
Publication Date: N/A
Technical Abstract: Damping-off of sugarbeets (Beta vulgaris) caused by Aphanomyces cochlioides causes extensive stand losses of sugarbeet seedlings under warm, moist conditions. To improve the assessment and selection of resistance to this disease, we are developing a growth chamber assay with tight control of abiotic factors such as moisture light and temperature that affect the host-pathogen interaction. Seedlings 5 days old, germinated on rolled germination paper, are inoculated in a zoospore suspension for 15 minutes, then incubated at 25 degrees C on fresh germination paper under constant light and moisture. Seedlings are evaluated daily for development of disease lesions, using a binomial system where less than 25% root/hypocotyl diseased is a "+", and >25% of root diseased is a "-". This rolled-towel assay provides discrimination between a moderately resistant variety (USH20) and a susceptible one (Edda). Future work will concentrate on use of this assay to assess varietal resistance and select resistant germplasm.