Timing interval important for fungicide applications to control septoria leafspot of celery

Difolatan, Daconil 2787, Dyrene and Benlate were significantly better than other fungicides tested for the control of Septoria apiicola Speg. when sprays were applied every seven days to plots showing severe disease development. When the same materials were applied at 14-day intervals under similar conditions, control of the fungus was unsatisfactory. Excellent control was obtained with these fungicides, or with TBZ in 1969 when they were applied every 14 days beginning as soon as lesions appeared on the leaves. These trials indicate that under California conditions, Septoria leafspot of celery can be controlled with a 14-day spray schedule using either, Benlate, Daconil 2787, Difolatan, Dyrene, or TBZ. Of these materials only Dyrene is registered for use on celery but has not yet been included in U.C. pest control recommendations.