Anthracnose - a new disease in Ontario vineyards

Anthracnose, caused by the fungus Elsinoe ampelina, is a problem in vineyards in the southern US but has been found as far north as Quebec and Nova Scotia, where it is commonly found in French hybrid varieties, especially Vidal, Vignoles and Reliance. Frontenac and Marechal Foch have been reported to have intermediate susceptibility to anthracnose. This disease was previously unreported in Ontario until this fall when it was found in a block of SV 23-512 in Elgin County. The symptoms first appear as small, round reddish spots on leaves. The centre of these lesions dies and falls out giving a shot-hole appearance. On stems and fruit, spots develop into sunken, grey areas with raised dark purple edges ("bird's eye" lesions). Anthracnose lesions on shoots may be confused with hail injury; however, unlike hail damage, the edges of the wounds caused by the anthracnose fungus are raised and black. In addition, hail damage generally appears on only one side of the shoot, whereas anthracnose is more generally distributed.

The pathogen overwinters in infected plant material such as shoots and berries. In the spring when the temperature is at least 2 C, spores are spread by wind and splashing rain and can infect all above-ground parts of the plant. Warmer conditions (up to 32 C) and frequent rains promote more severe infections
Sanitation is very important in controlling this disease. Prune out and destroy (remove from the vineyard) diseased plant parts during the dormant season. This includes infected shoots, cluster stems and berries. This should reduce the amount of primary inoculum for the disease in the vineyard.
Where the disease is established, especially in a commercial vineyard, the use of fungicides is recommended in Ohio. Ohio fungicide recommendations for anthracnose control consist of a dormant application of Liquid Lime Sulfur (112 L/ha), followed by applications of foliar fungicides during the growing season.

If you see these symptoms in your vineyard, please contact Wendy McFadden-Smith at (905) 562-3833 or wendy.mcfadden-smith@ontario.ca.

Bird's eye lesions of anthracnose on SV 23-512 in Ontario, 2008

Anthracnose lesions on shoots and leaves Note the shot holes where infected tissues drop out of leaves.
Source: http://ohioline.osu.edu/hyg-fact/3000/3208.html