ASSOCIATION BETWEEN GRAPE PHYLLOXERA AND STRONGLY RESISTANT ROOTSTOCKS IN CALIFORNIA: BIOASSAYS
Grape phylloxera Daktulosphaira vitifoliae populations were found in high numbers in a total of six Napa and Sonoma County vineyards on 101-14 Mgt or Teleki 5C roots. The phylloxera were only associated with nodosities and populations were easily found by excavating roots, though unevenly distributed. Laboratory bioassays with colonies established from three of the 101-14 Mgt sites indicated that these phylloxera were able to easily establish and reproduce on immature feeder roots of a number of rootstock types to a greater extent than were colonies established from field collected Vitis vinifera or AXR#1 roots. Phylloxera colonies arising from 101-14 Mgt fields established, developed and reproduced relatively poorly on most root types tested with V. vinifera parentage. These observations question the nature and durability of rootstock resistance conferred by wild American Vitis species.
Granett, J., Walker, M.A. and Fossen, M.A. (2007). ASSOCIATION BETWEEN GRAPE PHYLLOXERA AND STRONGLY RESISTANT ROOTSTOCKS IN CALIFORNIA: BIOASSAYS. Acta Hortic. 733, 25-31
Vitis vinifera, grape phylloxera, rootstocks, resistance