Rootstocks

Grape rootstock breeding advances have been substantial and new rootstocks have been released. Noteworthy advances and discoveries from the breeding program include:

The development and release of the five new GRN (grape rootstocks for nematode resistance) rootstocks with outstanding and broad nematode resistance for use with wine, raisin, and table grapes on nematode infested soils.

Rootstock trials in the San Joaquin Valley by farm advisors in Fresno and Kern counties.

The evaluation of techniques to reduce wood rot fungi in nursery mothervines and blocks.

The development of rootstock alternatives to Freedom with strong resistance to root-knot nematodes.

The discovery of strong resistance to ring nematodes in 039-16 and GRN-1; many other selections are being tested.

The evaluation of phylloxera resistance in fertile vinifera x rotundifolia hybrids leading to their use in breeding for nematode and fanleaf resistance.

The development of a rapid greenhouse assay for salt tolerance.

The collection and maintenance of approximately 1,000 accessions of southwestern grape species, many of which have salt and drought tolerance, and resistance to dagger nematodes and Pierce’s disease.

The evaluation of DNA from 500 phylloxera collections from across the US now allows the world to determine where their strains of phylloxera originated and how this key grape pest is evolving.

The mapping and characterization of the Xiphinema index resistance gene from V. arizonica.

The combining of strong resistance to nematodes, phylloxera, salt and drought with rootstock candidates under testing.