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What Are Nematodes?

Nematodes are predominantly tiny aquatic roundworms that thrive in nearly all environments on Earth. They are the largest group of multicellular species in the animal kingdom, making up about four-fifths of animal life on Earth. Some species are parasites of humans or animals. Other nematodes are parasites of plants and can cause economic losses in various food, ornamental, and industrial crops. Some species are considered beneficial as they are essential members of the food web and help in soil nutrient recycling. They feed on soil fungi, bacteria, algae, arthropods, or other nematodes. Nematodes are also one of the favorite model organisms in studies on molecular genetics. This workgroup primarily focuses on developing and extending information about plant-parasitic and beneficial nematodes.

Sting nematodes feeding on a corn root

root-knot nematode damage on carrots

California Nematology Information

Plant Parasitic Nematode Thresholds/Damage Levels

Crop damage is typically related to the population density of plant-parasitic nematodes at seeding or planting although plant species and cultivar response as well as soil biotic and abiotic factors may modify the crop injury extent. A Nematology Workgroup project compiled crop damage thresholds for some important nematode pests in California.

UC Nematology Stories

Grape vines are susceptible to diseases caused by various nematode species, including root-knot, root-lesion, ring, citrus, and dagger nematodes. Research has indicated that root-knot nematode species often adapt to invade previously resistant rootstocks within two to 14 years after planting. Once nematode populations develop the means to exploit one rootstock, they are then able to attack all the plantings using that rootstock. The damage caused by nematodes is economically significant, resulting in lost fruit and vine vigor for growers.

Read about: Nematologist Works on Resistant Grape Rootstocks | View Other Stories