California Agriculture

New reduced-risk fungicides are highly effective in managing both pre- and postharvest diseases of stone fruit crops in California, and they have replaced most previously registered materials. These fungicides have a low impact on the environment, high specificity to target organisms, and low potential for groundwater contamination and human health risks. In stone fruit, they can be successfully used to manage brown rot blossom blight in a new delayed-bloom fungicide application program for low-precipitation years. In our studies, we found that fungicide treatments applied 1 to 14 days before harvest were also effective against preharvest brown rot and protected fruit from fungal decays initiated during harvest. Practices such as mixtures and rotations can be implemented to prevent resistance from developing and to ensure the lasting efficacy of these reduced-risk fungicides.