My Muscadines Grow too Much Foliage & Few Grapes

Irrigation

• Grapevines require a sufficient amount of water on a regular schedule in order to produce a good yield. Drought conditions can cause a decrease in flower set clustering and fruit production according to Virginia Tech University viticulture specialist Dr. Tony K. Wolf. Reduce irrigation after harvesting to harden the vines for winter. Vines can experience freeze injury if irrigated too late in the fall.

Fertilization

• Muscadine grapevines are heavy feeders that need regular fertilization for fruit set and maturation. Fertilize each plant with one-quarter pound of 8-8-8 or 10-10-10 formula fertilizer after growth begins in the spring. Repeat application in late summer.

  Increase this to 1 to 2 pounds per vine in early spring the second year, and 3 to 4 pounds in future years, according to University of Florida horticulturist Peter C. Andersen. If overgrowth of vegetation at the expense of fruiting is a problem, apply a fertilizer with a lower nitrogen component.

Pruning

• If grapevines are not properly pruned, all the energy of the plant will go to producing leaves on the new growth instead of to fruit production on mature vines. Prune a central leader vine and prune out side shoots and unnecessary vining. Train the vines along trellis or support wires to support fruit as it becomes heavy.

  Since grapes generally take three years to produce a crop, prune the vines judiciously to encourage strong central vines and eliminate weak offshoots. Grapes grow on the previous years growth, so avoid overpruning which can inhibit fruit production.

Grapevine Diseases

• Muscadine grapes are sometimes subject to disease conditions that affect fruit-setting. Powdery mildew, an off-white powdery growth on the plant's surface, can reduce the size of berries and cause fruit drop. Black rot can also cause lesions on grapevine stems and tendrils. Bitter rot can cause shriveling and mummification of the berries, according to Library4 Farming writer E.S. Luttrell. Regular application of an effective fungicide like captan or sulfur helps to control these disease problems. Remove and destroy affected areas of plants to prevent the spread of the disease.