RELATIONSHIPS BETWEEN GRAPE PHYLLOXERA ABUNDANCE, FUNGAL INTERACTIONS AND GRAPEVINE DECLINE

Grape phylloxera (Daktulosphaira vitifoliae) populations were found in high numbers at two field sites in the north-east of Victoria, Australia, on Vitis vinifera ‘Cabernet Sauvignon’ roots. Differences in population abundance were observed with phylloxera genetic strain G4 being more abundant than G1. Root necrosis in phylloxera-infested grapevine roots reached levels of up to 26% and was associated with the presence of fungal pathogens, of which Fusarium oxysporum was the most prevalent. The implications for phylloxera management and detection are discussed.