Quantitative method of inoculation of celery plants withSeptoria apiicola

Celery (Apium graveolens L.) plants were inoculated with 3-µl droplets of a pycnidiospore suspension ofSeptoria 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.