Using Objective Biophysical Measurements as the Basis of Targeted Surveillance for Detection of Grapevine Phylloxera 'Daktulosphaira vitifoliae' Fitch: Preliminary Findings

In Australia early detection of grapevine phylloxera ('Daktulosphaira vitifoliae' Fitch) is critical for the sustainability of its viticultural industry which is predominantly planted on phylloxera-susceptible ungrafted 'Vitis vinifera' L. The current range of available early detection methods, including ground surveys and aerial imagery, rely on detection of a 'weak spot' in the vineyard resulting from the expression of non-specific, often non-phylloxera related, plant stress. These methods are costly and labour intensive. Other evolving methods include chemical fingerprinting and soil-based DNA probes. However, there is a need to develop biophysical descriptors that directly indicate the potential susceptibility of vineyards to phylloxera infestation. Quantitative biophysical indicators including vine photosynthetically-active biomass (PAB), soil electrical conductivity (ECa), soil particle-size and soil chemistry have been evaluated for their ability to facilitate targeted and intensified surveillance. Phylloxera monitoring was conducted in infested vineyards in Central Victoria, Australia over two successive growing seasons. Soil ECa was derived using EM38 and PAB was derived using airborne multispectral imaging. Results indicated zones of higher ECa and higher exchangeable aluminium, were associated with higher populations of phylloxera. Further studies are required to quantify the link between phylloxera dispersal and soil parameters, however the results were encouraging for developing a grapevine susceptibility matrix as the basis for an objective monitoring protocol.