Currently-available commercial grape rootstocks have a number of serious shortcomings, including narrowness of soil pest resistance, excessive vigor except in the sandiest of soils, and a lack of long-term resistance to a specific soil pest of considerable importance, namely root knot nematodes.

A University of California scientist has developed two new grape rootstocks (designated RS-3 and RS-9) that feature broad-spectrum resistance to nematodes, including aggressive root knot nematodes. RS-3 has a moderate vigor level that is most suitable for coarse to fine sandy loam soils, and displays resistance to all known aggressive populations of root knot nematodes, to Xiphinema index, the citrus nematode (Tylenchulus semipenetrans) and to root lesion (Pratylenchus vulnus). RS-9 has a lower vigor, which will probably be better suited to coastal valleys. RS-9 also exhibits good resistance to root knot nematodes, Xiphinema index, and P. vulnus, and should be considered in cooler regions where ectoparasitic nematodes predominate. Overall, RS-3 and RS-9 offer broader nematode resistance than grape rootstocks such as VR 039-16, Freedom, Harmony, Ramsey, or Teleki 5C(6), coupled with an attenuation of vigor that is desirable in many kinds of soils.

File Number: 10240 

Web site: http://techtransfer.universityofcalifornia.edu/...