Sustainable Phylloxera management phase 11

Abstract

Phylloxera is a serious threat to production and deserves attention on several fronts, including expansion of knowledge of the pest through research, examination of the circumstances and implications surrounding outbreaks, improvement of practices in infested vineyards and extension of information to grapegrowers.

Summary

Activities in this phase of phylloxera research had components of research into clonal interactions with different rootstocks, assessment of dry heat treatments, extension to grapegrowers and monitoring of new infestations. The opportunity to study new infestations came with discovery of phylloxera at Porepunkah in November 2007 and at Lancefield in January 2008, when trapping and monitoring of vine vigour gave an insight into spreading patterns and population dynamics. The genotype G4 at Porepunkah for instance was characterised by its fast spread as opposed to a different pace for the genotype G1 at Lancefield. Soil factors were examined and it was found that areas of higher electrical conductivity (EC) were either favoured for establishment or were more likely to show symptoms first. The most revealing component of this project came when laboratory trials to screen for phylloxera resistance (comprising six selected phylloxera genotypes and seven rootstocks) were conducted.

Results added to information about the spread of the pest and the behavior of different genotypes. They differ in amount of egg production and the number of eggs that survive to go on to be adults. Generally grafted vines have greater tolerance than ungrafted vines but even so-called “resistant” rootstocks can carry populations to adulthood. This does not mean roots are infested but highlights a risk of persistence and spread. An illustration is that while 1103 Paulsen with G7 did not have development of the insect beyond crawler stage, indicating a highly resistant interaction, rootstock 919 high numbers of eggs and adults of this genotype. Interestingly there was the first reported incidence of “highly resistant” rootstock Borner associated with G7 and G30 genotypes beyond crawler stage in controlled conditions.

The project has expanded knowledge on a number of fronts and in particular has drawn attention to differences in genotype and rootstock interactions.