Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/16/2006
Publication Date: 7/28/2006
Citation: Shepherd, L.M., Block, C.C. 2006. Optimization of blotter test protocol for blackleg detection in brassica seed [abstract]. American Phytopathological Society Annual Meeting. 96:S107.
Technical Abstract: Leptosphaeria maculans (anamorph: Phoma lingam) is a serious seed-borne pathogen of Brassica crops, and seed health testing is important in preventing disease in the field. This study examined three variables in a National Seed Health System blotter test protocol for P. lingam. Artificially-inoculated seed lots were used for all experiments. The variables studied were pre-incubation (imbibition) time at room temperature (24 vs. 48 hr), length of freezing time to kill the seeds (8, 16, or 24 hr), and post-freezing incubation temperature (20, 24, or 28C). A second set of experiments was conducted to determine if Botran, a fungicide used to reduce Rhizopus sp. growth on the blotters, interferes with recovery of P. lingam. Rhizopus is a common problem in blotter tests and extensive growth obscures and seems to inhibit growth of Phoma. Extensive seed germination at the 48-hr pre-incubation time was correlated with reduced Phoma recovery compared to the 24-hr time. The length of freezing did not significantly affect P. lingam recovery. Incubation temperature did affect detection of the pathogen and there was a general downward trend in detection as temperature increased from 20C to 28C. The addition of Botran to malt agar slowed fungal growth as concentration increased, but only the highest concentration (0.1%) showed a possible effect on blotters.