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Identification of cause and origin of crown gall-like symptoms in vineyards

Summary

Objective

This project aims to address the occurrence of crown gall-like symptoms in commercial and propagation winegrape vineyards in Australia. Specifically, the objectives are to:

  1. Identify the pathogen(s) causing crown gall-like symptoms observed within the last three years in Queensland, Australian Capital Territory, Victoria and New South Wales 
  2. Understand the factors influencing severity of symptom expression in vineyards
  3. Understand how the pathogen(s) is spread
  4. Develop a diagnostic assay that ensures specificity, accuracy, and rapid turnaround time, and is suitable for adoption in commercial diagnostic laboratories.
     

Background

Crown gall is a plant disease endemic to Australia that affects grapevines and a wide range of other horticultural crops. It is caused by bacteria from two genera, Agrobacterium and Allorhizobium, both belonging to the Rhizobiaceae family. While pathogenic and non-pathogenic strains of these bacteria are commonly found in soils and water worldwide, their presence alone does not necessarily result in disease.

The disease sporadically emerges in Australian vineyards, but occurrence is relatively infrequent. The recent appearance of crown gall-like symptoms in several wine regions highlighted the absence of diagnostic tests able to identify the causal pathogen/s and to track disease origin and spread.

While some cases are seemingly attributable to infected planting material, others indicate the involvement of environmental conditions, cultural practices, or a combination of these and potentially unidentified factors. Consequently, batches of planting material displaying crown gall symptoms in one region or vineyard may exhibit no symptoms elsewhere.

An industry response group was formed, led by Wine Australia and comprising representatives from key sector organisations. The group met frequently to monitor the situation, share information and provide the latest knowledge to stakeholders. A request for proposal was developed to procure a project to address the key research gaps. Specifically, these were to identify the pathogen/s responsible for causing crown gall-like symptoms, understand the factors influencing severity of symptom expression in vineyards, design a reliable diagnostic assay for the pathogen/s and trace the source(s) of the infection.

Sector benefits

Although crown gall occurrs sporadically in vineyards, it can have devastating effects on affected growers and suppliers of propagation material. This project aims to generate knowledge essential to  understanding the current situation and developing effective measures for prevention and control of crown gall in Australian vineyards.

This content is restricted to wine exporters and levy-payers. Some reports are available for purchase to non-levy payers/exporters.

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This content is restricted to wine exporters and levy-payers. Some reports are available for purchase to non-levy payers/exporters.