Cause Heterodera humuli. Cyst nematodes are sedentary endoparasites. Surveys in 1961-1962 determined the presence of this nematode in hop yards near Independence and Salem, OR. Movement of hop roots from yard to yard and area to area, combined with annual flooding, probably has widely distributed the pest.
Symptoms White to brown protuberances (cysts) on roots.
Sampling Infective second-stage juveniles, adult males (rarely), and cysts (the female's dead body, which contains eggs) can be obtained from soil samples. However, cyst extraction requires a special extraction procedure; so if a cyst count is desired, noted that on the form accompanying the sample. During the growing season, it helps to send roots as well as soil to assist the diagnosis.
Cultural control No control has been developed.
Biological control
- LALNIX ACT DC at 10.25 fl oz/A at 4- to 6-week intervals for nematode suppression. Apply when soil temperature at a depth of 4 inches is consistently 60ºF. See label for specific application types and timings. 24-hr reentry. O
Reference Jensen, H.J., Smithson, H.R., and Loring, L.B. 1962. The hop cyst nematode (Heterodera humuli Filpjev, 1934) found in Oregon. Plant Disease Reporter 46:702.