Anthracnose of Grape (Elsinoë ampelina)

Anthracnose is a grape rot disease, caused by fungus Elsinoë ampelin. It’s also kAnthracnose is a grape rot disease caused by the fungus Elsinoë ampelin. It’s also known as bird’s-eye rot due to the look of the symptoms that appear on the infected plant. The disease is widely recognized in rainy, warm and humid climates, and can be very destructive once occurs in the vineyard. It reduces fruit quality and quantity and weakens the vines.

Symptoms of Anthracnose

Most winegrowers are familiar with the symptoms of shoots and berries, but Anthracnose can also attack fruit stems, leaves, tendrils and petioles. Disease is more dangerous when it occurs on young leaves. Infected leaves are usually full of spots with grey centres and brown-to-black margins with round or angular edges. The grey centre of the spots eventually dries and drops out, so the leaves look like they have been shot through. If spots cover the entire leaf or affect leaf veins, the whole leaf eventually dries out. Symptoms on shoots first appear as small, round, reddish spots. Eventually, the spots enlarge and generate grey centres with reddish-brown to black margins and round or angular edges. On infected lesions, shoots can crack and become brittle or die out. Berries can get infected anytime between the pre-flowering and the veraison development stage. Similar to the shoots, also on berries, symptoms of infection first appear as small, round, reddish spots. After some time, spots enlarge and appear as “bird’s eye” – with grey centres and reddish brown to black margins. Infected spots can then extend into the pulp and cause cracking of the berries. Under favourable weather conditions, fungal fruiting bodies develop in the lesions and appear as pinkish spores.

Anthracnose Disease cycle

The Anthracnose fungus overwinters in infected shoots, canes and/or berries. In the spring, when favourable wet weather conditions exist, spores called conidia develop. These spores are then spread around with the rain. Infection time depends on moisture and temperatures; heavy rain and warm temperatures are ideal for the disease development. Optimum conditions for primary conidia infection are 12 hours of moisture and temperatures in the range between 2°C and 32° C. Symptoms of the disease develop 13 days after the infection if the temperatures are around 2°C and after 4 days if the temperatures are around 32° C. After disease occurrence, the asexual fruiting bodies (acervuli) appear on infected areas and produce conidia during the wet weather. These conidias are then the source of secondary infections.

Disease management

Anthracnose is a grape fungal disease that thrives in rainy and warm conditions, with the risk of infection increasing as temperatures rise. The disease can be efficiently controlled through good cultural practices, such as removing and destroying infected plant parts and eliminating wild grapes near the vineyard. Planting resistant varieties and improving air circulation through proper training systems and leaf removal are also helpful. If Anthracnose does appear, fungicide sprays like sulfur or copper can be used. Vineyard management decision support systems like eVineyard can offer timely advice on when to spray, helping to protect your vines from the disease.

Winegrowers, are you familiar with the symptoms of bird’s-eye rot and its management practices, or is there anything else you would like to add?

Sources:

• Michael A. Ellis and Omer Erincik. Anthracnose of Grape. 2008. Ohio State University Extension.
• John R. Hartman and Cheryl A. Kaiser. Fruit Rots of Grape. University of Kentucky, Cooperative Extension Service.
• University of Minnesota Extension. Grape: Dried fruit disease symptoms. University of Minnesota. (online).
• Grape Anthracnose; Purdue University
• Featured image: by CSIRO; via Wikimedia Commons