are microscopic roundworms that live in soil and feed on plant roots.
Aboveground symptoms are poor growth, low yields and an off
color. The symptoms may resemble those of nutrient deficiencies or virus
diseases. Belowground symptoms include poor root development, root browning,
root swelling and stunting or death of feeder roots. In new vineyards,
nematodes may cause poor establishment and weak growth of young vines.
Nematodes seldom kill vines but contribute to a steady decline in vigor.
Some nematodes are also vectors of viruses. Nematodes spread with soil
and plant roots. Once established in a vineyard, nematode infestations
tend to be permanent.
|Left, roots with black discoloration caused by dagger nematode. Right, healthy roots.