Ben-yephet, Y., Dept. of Plant Pathology, ARO, The Volcani Center, Bet Dagan, 50250, Israel
Pressman, E., Dept. of Vegetable Crops, ARO, The Volcani Center, Bet Dagan, 50250, Israel
Evenor, D., Dept. of Vegetable Crops, ARO, The Volcani Center, Bet Dagan, 50250, Israel
Rappaport, L., Dept. of Vegetable Crops, University of California, Davis, CA, United States

Celery (Apium graveolens L.) plants were inoculated with 3-μl droplets of a pycnidiospore suspension of Septoria apiicola Speg., and then covered with polyethylene bags and kept at an ambient temperature of 23±2°C. Under these conditions disease expression was related to incubation time up to 8 days, and to spore concentrations up to 500/3 μl. An inoculum concentration as low as four viable spores per 3 μl caused 26% as many lesions as did 500 spores/3 μl. In plants not covered, or covered with polyethylene bags for only 1 day, no disease symptoms appeared regardless of the spore concentration applied to the plants. Disease symptoms on inoculated leaves appeared on 10-50-day-old but not on 50-90-day-old leaves. The pathogenicity of 16 isolates collected from two different regions of Israel, and of eight replicates of an isolate used in previous pathogenicity tests, was similar. © 1992 Springer Science + Business Media B.V.