By Andi Anderson
Grapevine decline is a major concern for Michigan vineyards, drastically shortening their productive life. This issue is caused by various fungi that infect the wood, leading to diseases like Eutypa dieback and Esca complex.
These diseases often enter vines through pruning cuts, especially in Michigan's cool climate, where winter injury can make vines more vulnerable. Proactive prevention is key to long-term vineyard health.
Every pruning cut creates an open door for pathogens. Fungal spores, carried by air and rain, can infect fresh wounds, particularly if conditions are wet. Wounds can remain susceptible for several weeks.
To minimize risk, avoid pruning in wet weather. Cold, dry, and sunny conditions allow cuts to heal faster and reduce infection chances.
Delaying pruning until late dormant season, around March or early April, is also beneficial. Wounds made in warmer spring conditions heal quicker and face lower pathogen levels. For large vineyards, "double pruning" involves an initial cut, followed by a final trim closer to budbreak, removing potentially infected stub wood.
Always prune healthy blocks first to prevent spreading diseases to cleaner areas. Minimize large cuts into old wood, as these are harder for the vine to heal.
When large cuts are necessary, angle them to shed water and consider leaving a small "desiccation stub" to protect the main trunk.
Protecting pruning wounds with fungicides or biological sealants is an important extra step. Apply these protectants within 24 hours of pruning. Dormant sprays like lime sulfur can also disinfect fresh cuts and control other fungi. Avoid using plain paint or wax, as they are not effective and can trap moisture.
Good vineyard sanitation is crucial. Remove and destroy any infected wood, as fungi can continue to release spores from dead material.
Regularly disinfect pruning tools, especially after working on diseased vines, using solutions like 70% alcohol or 10% bleach. By following these practices, growers can significantly reduce grapevine decline and extend the life of their vineyards.
Photo Credit: pixabay-vinotecarium
Categories: Michigan, Crops, Fruits and Vegetables, Rural Lifestyle