How can I manage anthracnose in high-tunnel grape production?
Answer: Anthracnose is a widespread problem in outdoor vineyards, but high tunnels may limit incidence of anthracnose by reducing rain splash, which is the primary means of spore dispersal. The disease is favored by warm and humid climates. Once established, it can be very difficult to manage, resulting in significant yield loss and a reduction in fruit quality. Fungal spores overwinter on infected canes or berries and spread to young, succulent shoots and berries after germinating in the spring. Initially appearing as small reddish spots, it later progresses to brownish lesions with gray centers and dark margins. Older lesions may fall out, resulting in a “shot hole” appearance, or coalesce into large patches, giving the leaves a deformed look.
Anthracnose management starts with proper vineyard sanitation, so removing infected canes and berries should be the first step. If infected berries are too numerous to remove completely, burying by cultivation or mulching can also be successful. When sanitation is not sufficient for control, fungicide applications can help reduce disease problems. A delayed-dormant application of lime sulfur or copper product shortly before bud-break is critical for control in many systems. Foliar fungicides applied on a seven- to 14-day interval are also recommended during the growing season (Brannen and Cline, 2019; Smith et al., 2020).
You can learn much more about grape pests in the new ATTRA publication High Tunnel Grapes: Pest Management. This publication is the fourth in a series on high tunnel grape production, based on research led by Dr. Elena Garcia at the University of Arkansas. It covers general guidelines for integrated pest management (IPM) of high tunnel grapes, methods of scouting for pests, descriptions and controls for the most important diseases and insect pests, and an example spray schedule for both conventional and organic production of grapes in high tunnels.
While you’re at it, check out the other three titles in this series, too:
In addition, ATTRA has produced several videos on high tunnel grapes that you’ll find useful:
Brannen, P., and B. Cline. 2019. 2019 Southeast Regional Bunch Grape Integrated Management Guide. University of Georgia Cooperative Extension, Athens, GA.
Smith, S., J. Boyd, N. Burgos, D. Johnson, J. Lee, and S. Sanders. 2020. Arkansas Small Fruit Management Schedule – 2020. University of Arkansas System Division of Agriculture, Fayetteville, AR.