No. 10 — May 27, 2019


close-up of grape clusters with eye rot spots speckling the fruit
Birds eye rot caused by Anthracnose Elsinoe ampelina on the grape cultivar Louise Swenson. Photo credit: D.S. Volenberg archived 8.12.14

With continued long wet periods and rising temperatures be keenly aware of the potential of anthracnose infections. Anthracnose is caused by a fungus Elsinoe ampelina. The fungus overwinters on infected canes and spores (conidia) are released during extended wet periods. The violent thunderstorms which continue to persist provide ideal conditions to transport the spores throughout the vineyard. Once anthracnose is established in the vineyard there is the potential for continued spread throughout the growing season.

Anthracnose is more than a foliar fungal problem and can cause fruit rots. As the grapevines progress from bloom to berry set consider using fungicides that will provide protection from anthracnose infections. Especially when protracted wet warm conditions persist. Both captan and ziram will provide protection to infection from anthracnose. In addition, mancozeb will also provide protection but be aware that mancozeb products have a 66-day PHI.

Some grape cultivars are more susceptible to anthracnose infection than others. Susceptible cultivars include; Vidal blanc, Marquette, Frontenac, LaCrescent and, most all, of Elmer Swenson’s cultivars.

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