NEW HYBRID ROOTSTOCK RESISTANCE SCREENING FOR PHYLLOXERA UNDER LABORATORY CONDITIONS

Abstract

Grafting Vitis Vinifera, European grapevine onto rootstocks (hybrids of American Vitis species) is a successful long-term management tool for both phylloxera resistance and other important traits for grapegrowers worldwide. Rootstock improvement and breeding for specific environmental conditions is important for the viticulture industry. However, most of the commercially available rootstocks in Australia were bred outside the country. Some of the most important features for rootstocks grown under Australian conditions include nematode resistance, salt tolerance, drought tolerance, graft compatibility and phylloxera resistance. A laboratory rootstock screening method was developed to test the resistance of newly developed rootstocks in Australia against two selected phylloxera genetic strains (designated G4 and G30). Screening was conducted on excised grapevine roots under controlled laboratory conditions. The development and survival of two phylloxera clones was compared on three newly released rootstocks (two V. cinerea var. helleri crosses and one V. cinerea cross) and ungrafted V. Vinifera. Relative resistance levels from the screening process are presented, which highlight that both G4 and G30 phylloxera developed on the V. cinerea cross, neither developed on one of the V. cinerea var. helleri cross rootstocks and only G4 developed on the other V. cinerea var. helleri cross rootstock.