Plant parasitic nematodes are microscopic roundworms that live in soil and plant tissues. They feed on plants by puncturing and sucking the cell contents with a spearlike mouthpart called a stylet. Of the several genera of plant parasitic nematodes detected in California orchard soils, lesion and root knot nematodes are considered to be important factors in limiting plant growth. Dagger nematode can reduce growth but is more important as a virus vector. Pin nematode is common, but effects on cherry have not been studied and it is not considered a pathogen on other stone fruits.
Damage caused by nematodes is likely to become evident during the first year after planting.
Feeding by nematodes can impair root functions such as uptake of nutrients and water. Lesion nematodes penetrate into the roots and cause damage by feeding and tunneling through the root tissues. Dagger nematodes feed from outside the roots, but can reach the vascular tissues with their long stylet and are capable of reducing vigor and yield of trees. However, X. americanum is more important on stone fruit trees as a vector of the cherry rasp leaf virus, which cause raspleaf disease, and strains of tomato ringspot virus, which cause yellow bud mosaic, cherry mottle leaf, and Prunus stem pitting diseases. These virus diseases can reduce the productivity of the trees significantly, and infected trees may eventually die.