Pests and diesease update

Several new plant pest detections in Australia highlight why vineyard hygiene and surveillance will become increasingly important in Australian vineyards.

We all have a much deeper understanding of the importance of biosecurity and its worth taking the time to think about how this new knowledge might be applied to protecting vine health.

If you spot anything unusual in the vineyard, it always pays to be vigilant and report it. In fact it’s a legal requirement to do so. By doing the right thing, you are potentially protecting all of Australian agriculture for the unwanted consequences of a widespread pest or disease outbreak.

It’s also worth being aware of the provisions for owners to be reimbursed for financial losses incurred due to a response to an exotic pest incursion. This is designed to ensure that growers have the confidence to meet their obligations to report exotic pests.

Timely and accurate identification about the presence of new pests and diseases is essential for control and potential eradication of new pests. Advances in plant disease detection and monitoring such as through the use of high throughput sequencing has enabled the discovery of new or obscure non-target viruses.

Use of this diagnostic has led to the discovery of previously unidentified strains and species, that are thought to have been present in Australia for a long time but without identification.

Grapevine Pinot gris virus was one such example. This virus has now been detected in NSW, Victoria and South Australia. We are yet to fully understand the impact that this virus will have on vine health however we do know that it displays symptoms in many varieties other than Pinot gris.  The fact that it is often found in infections with a mix of other viruses adds to the challenge of understanding its current and potential impact.

In early 2021, there were five previously undetected soilborne fungal species found in Australia, all thought to have been present for a number of years.  The species are all known to cause ‘black root rot’ in trees and vines, one of the main soilborne fungal diseases affecting grapevine production worldwide.  Black foot rot disease can lead to severe necrosis of the root system causing stunting, wilting, leaf chlorosis, browning and leaf drop.  Typical indicators include reduction in root biomass and root hairs with sunken and necrotic lesions.  The species identified were Dactylonectria estremocensis, D. pinicola and Ilyonectria capensis in Victoria, and D. alcacerensis and D. palmicola in Queensland. In April 2022, Diatrype stigma (a Grapevine trunk disease) was detected in spore traps in South Australia and New South Wales. Growers suspicious of an unknown pathogen in their vineyard should take care to contain any potential spread by not to removing infected plants from the property unless it is through an approved council collection. Suspect vines or other plants should be reported to the Exotic Plant Pest Hotline on 1800 084 881.

The fact that these diseases are likely to have been present for quite some time with limited damage means these detections should not be treated as emergency. However, it serves as a reminder that we are in an environment of increasing global spread of pests and diseases, enhanced transmission pathways and a changing climate means new incursions and/or the spread of existing pests and diseases are becoming more and more of a threat to plant and animal industries.

2022 also saw a new pest notification of strawberry latent ringspot virus in parsley seed purchased from a national hardware chain. The virus can cause significant yield losses in affected plants including grapes. As there have been no detections in the field, it is hoped that the virus will not transfer form backyard vegetable gardens to commercial agricultural crops assuming pathways for its spread are limited.  As always, it is recommended that industry continue to practice good hygiene with all vineyard equipment and hand tools and to keep an eye out for any symptoms through surveillance and monitoring.

More information regarding exotic pests and diseases is available on the Plant Health Australia website.