Growers are in their vineyards every week. They are the eyes and ears of our biosecurity army. Active surveillance for grape phylloxera requires practical and effective tools for growers and regulators alike.
Vinehealth Australia has just completed a six-year project named ‘Sampling strategies for sensitive, accurate cost-effective detection of grape phylloxera for quantifying area freedom status’ co-funded by Plant Biosecurity Cooperative Research Centre (PBCRC) and Wine Australia.
A cross-functional project team carried out the work, made up of various members of Vinehealth Australia, scientists from the South Australian Research and Development Institute (SARDI) and The University of Adelaide, a statistician from Rho Environmetrics, and biosecurity officers from Biosecurity SA, Department of Economic Development, Jobs, Transport and Resources (DEDJTR) and NSW Department of Primary Industries.
The aim of this project was to develop a simple field sampling protocol for the collection of soil cores that could deliver cost-effective, sensitive and accurate detection of grape phylloxera DNA using a molecular biology technique called quantitative PCR (qPCR). This ‘DNA method’ does not require collection of whole insects but can detect phylloxera DNA from all stages of the insect’s lifecycle including eggs as well as body parts like legs.
The field sampling protocol for the DNA method was developed with information obtained from a number of studies investigating the effect of various factors on phylloxera presence or absence and amount of phylloxera detected. Such factors included:
- Timing of soil sample collection within and across years;
- Position, depth, location in the vineyard for soil sampling;
- Number of soil cores collected within the sampling area;
- Pooling of individual soil cores into composite soil samples; and
- Temperature and duration of soil sample storage.
This project also included outcomes of a study undertaken to compare three primary phylloxera detection methods: DNA, emergence trap and visual root inspection. This study showed differences in detection rates at landscape, block, composite sample and vine level.
This project has recommended that the DNA method be included in the National Phylloxera Management Protocol as a primary phylloxera detection method.
Endorsement of this method, alongside the emergence trap method and the currently endorsed visual root inspection phylloxera detection method, will provide growers and regulators with an integrated toolkit of field sampling and detection options to utilise as part of national surveillance plans. This will enable greater confidence in area freedom status, delimiting of incursions and upgrading phylloxera management zone status from a Phylloxera Infested Zone or Phylloxera Risk Zone to a Phylloxera Exclusion Zone.
Vinehealth Australia will continue to extend outcomes from this project over the coming months.