Nematode Symptoms in Grapevines

The soil around grapevines should be kept clean to keep the plants healthy.

The soil parasite known as a nematode exists worldwide. Its primary host is the grapevine, but nematodes also will feed on woody plants, tree fruit, cereals, soybeans and corn. There are many varieties of nematodes including citrus nematode, lesion nematode, ring nematode, the root knot nematode and the dagger nematodes. Of all the varieties, the root knot nematode does the most damage.

Dagger Nematodes

Dagger nematodes transmit the grapevine disease known as grapevine fanleaf. The symptoms of this disease include shortening of nodes, a zig-zag growth pattern of the shoots, asymmetric blades that look like a fan, and indentations on the leaves. Over the long term, the fruit yield will also be reduced by half with this nematode present. The best means of treating this nematode is through only growing dagger nematode-resistant varieties in your vineyard.

Tobacco Spot Ring

Tobacco spot ring virus is caused by the nematode variety Xiphinema americanum, which is the name for the American dagger nematode. Symptoms of this virus in grapevines include distortion of foliage, reduced leaf size and leaf molting. According to Dr. Judith Monis, Plant Health Services Manager at STA Laboratories, Inc., tobacco spot ring has been reported in New York and Pennsylvania.

Root Gall

The most destructive of all nematodes, root knot nematode eats into the roots of the grape plants. The best way to recognize the presence of this nematode is by observing the irregular clusters of unhealthy plants throughout the vineyard. The nematodes cause irregular cell growth in the roots, causing the roots to form galls, or giant balls, along the roots. When this happens, the plants cannot efficiently absorb water and nutrients from the soil.

Life Cycle

Nematodes are efficient feeders and they reproduce very quickly. Unlike most animals, nematodes can self-fertilize, so it is actually very rare to find any male nematodes. Once the nematode female self-fertilizes, she lays between 500 and 1,000 eggs during the late summer. By midwinter, the eggs have hatched and the second stage nematodes are already feeding on the grape roots.

References

• University of California Agriculture and Natural Resources: Grape Nematodes; B. B. Westerdahl; October 2008
• "Pinpointing Grapevine Virus Diseases: Part II"; Judit Monis, Ph.D.; Wine Business Monthly; March 2006
• HYPP Pathology: Grapevine Fanleaf Virus
• Plant Pro: Nematodes