The same conditions also favor gray mold and these same fungicides will also control gray mold. Carrots Symptoms of Alternaria leaf blight and Cercospora leaf blight are now appearing on carrots. Control measures include chlorothalonil or fixed copper materials. Some carrot cultivars are quite resistant to these diseases, but most cultivars need to be sprayed, especially in wet years where the foliage does not dry during the day and can remain wet for many days in a row. Symptoms of Alternaria leaf blight include a browning or necrosis of the leaf tips and loss of foliage while symptoms of Cercospora leaf blight include circular brown lesions on the leaf blades and elliptical brown lesions on the leaf petioles.
Affected petioles are brittle and easily broken at harvest.
Larry Binning, UW-Horticulture, will be on hand to provide a walking tour of the vine desiccation trials. The first application of a wide range of vine desiccants was applied earlier this week. There are several labeled as well as experimental treatments in this trial. Walt Stevenson, UW-Plant Pathology, will provide a walking tour of field plots related to late blight and early blight management. We have 64 fungicide programs in trial this year and have seen pressure from both late blight and early blight.