Resistance of autotetraploids of grapevine rootstock cultivars to phylloxera (Daktulosphaira vitifoliae FITCH)

Resistance of colchicine-induced autotetraploids of four grapevine rootstock cultivars (Riparia Gloire de Montpellier, Rupestris St. George, Couderc 3309 and Kober 5BB) to phylloxera (Daktulosphaira vitifoliae FITCH) was evaluated using the aseptic co-culture technique of root segments and phylloxera in a petri dish, and compared with those of the original diploid and Cabernet Franc (Vitis vinifera L.). None or very few phylloxera nymphs grew to adults on the root of the rootstock cultivars and their autotetrapolids whereas 26.8 % of the eggs grew to adults on the roots of Cabernet Franc. Resistance of Riparia Gloire de Mont-pellier, Rupestris St. George, Couderc 3309 and their autotetraploids to phylloxera was also tested by planting in a phylloxera-infested vineyard and compared with that of Kyoho, a tetraploid table grape cultivar (V. vinifera x V. labrusca Bailey). The formation of galls on the root tips of tetraploid rootstock cultivars was not increased significantly as compared to that on their original diploid plants whereas galls were formed on 52.9% of Kyoho root tips examined. These results show that the autotetraploid rootstock cultivars used in this study had high resistance to phylloxera, thus they were not different from the original diploids.