Why Is My Vineyard Turning Yellow?

Genetic Diseases

• Inferior or weak grape stock plants can suffer from afflictions such as corky bark, grapevine yellows disease, fanleaf degeneration and leaf roll. The leaves roll up and turn yellow. The only cure is to start over and replace the vines with certified healthy ones. After all the work that goes into the preparation and planting, this can be devastating news.

Pests and Fungi

• Grape vines are particularly susceptible to various types of mites and hoppers. They feed on the leaves and cause them to curl up and turn yellow. Downy mildew is a fungus that can afflict vineyards and turn the leaves yellow. An effective way to combat any of these is to identify the problem and spray the vines with the appropriate fungicide or insecticide.

Magnesium and Nutrients

• An imbalance of magnesium and potassium will cause yellowing of grape leaves before fall. This condition is particularly prevalent in acid soils, where adding lime and potassium to the soil to correct the pH levels causes a chemical reaction that makes the magnesium unavailable to the plants. Other nutrient deficiencies including nitrogen, phosphorous and iron can also cause the leaves to turn yellow. Have an expert analyze your plants to find out how to correct the problem.

Water

• Grapevines lose water by transpiration and evaporation. Young plants need regular water and must be irrigated regularly for the first two years of their lives. Older plants can live with little water for periods of time but yellowing of the leaves is one of the first symptoms of dryness.