Why Are Grape Leaves Folding Over and Turning Brown?

Grape Leafroll Disease

• Grape leafroll disease is a viral condition found in both large vineyards and individual plots although it is less common in home gardens. This viral disease infects grapevines in a variety of ways, via injury through improper pruning or pest damage, as well as through the soil. Grape leafroll disease causes the leaves of the grapevines to roll up as the disease progresses; eventually, the leaves turn brown and drop from the vines.

Controlling Grape Leafroll Disease

• Viruses, unlike bacteria and fungi, cannot be controlled with chemical sprays. Cultural care, including proper watering, fertilization and pest control, help limit the likelihood of disease contraction and slow the progression of the disease if it does appear. Plants that are infected by grape leafroll disease do not recover and have the potential to spread the virus to other, healthy plants. Remove and destroy infected grapevines to control the leafroll virus and minimize pest problems to lessen the chances of spreading the disease.

Nutrient Deficiency

• Phosphorus and potassium are two essential macronutrients that must be present in the soil for successful growth of grapevines and the production of fruit. A deficiency of these nutrients in the soil causes the leaves of a grapevine to mimic symptoms of grape leafroll disease, including rolled, brown leaves. Add a fertilizer to the soil that contains phosphorus and potassium to see if the plant recovers; fertilizer is crucial to the health of grapevines.

Chemical Damage

• Some herbicides have the potential to damage the leaves of grapevines; herbicides that are sprayed to control weeds, if present in large enough concentrations, can cause grape leaves to roll up and turn brown. Excess exposure to herbicides has the potential to kill some leaves although the chemicals are rarely fatal to grapevines. Water the grapevines regularly and avoid spraying herbicides near the garden to prevent further damage and allow the leaves to recover.