Cause Heterodera trifolii, a cyst nematode that is a sedentary endoparasite. Although this pest occasionally is found in western Oregon on roots of various legumes, little information about it is available. Ladino clover and hairy vetch are infected frequently.
Symptoms Plants look unthrifty and generally stunted. Under magnification, brown females, resembling miniature lemons, can be seen on roots.
Sampling Infective second-stage juveniles, adult males (rarely), and cysts (the dead body of the female, which contains eggs) can be obtained from soil samples. However, cyst extraction requires a special procedure; so note on the form accompanying the sample that a cyst count is desired. During the growing season, it is helpful to send roots as well as soil to assist the diagnosis.
Cultural control
- Rotate field out of legumes.