Changes in the efficacy of fungicidal control of onion white rot

摘要

Disease incidence data from field trials on the control of onion white rot (Sclerotium cepivorum Berk.) in the Pukekohe district of New Zealand over the period 19979-99 were reviewed. It was shown that the efficacy of the fungicides iprodione, procymidone, tebuconazole and triadimenol varied greatly from year to year. There was no relationship between efficacy and a range of agronomic and environmental factors, and the variations were most likely to be the result of changes in soil conditions that affected the persistence or activity of the fungicides in the soil. The commercial experience of unpredictable performance of the fungicides from year to year was confirmed.