The Department of Agriculture and Water Resources has recently implemented emergency quarantine measures to reduce the likelihood of entry of the bacterial plant pathogen Xylella fastidiosa and related Xylella species. These emergency quarantine measures will see changes to the import conditions around a significant number of plants for nursery stock.
Xylella is a complex bacterium with a number of subspecies. Its host range is quite considerable with some hosts being asymptomatic.
The bacteria lives within the xylem of plants, and can impact upon plant health by multiplying and forming a bacterial gel which then restricts or blocks the xylem, impacting upon the flow of water in the plant. The bacteria are naturally spread by insect vectors which feed upon the xylem. Once the insect feeds upon the xylem it also ingests the bacteria and this can then be spread to other plants as the insect moves and feeds on other plants. A number of Australian insects could potentially acts as a vector for Xylella. Of particular note for our industry the bacteria can also be spread to new areas through the trade of infected plant material. Chemical control for Xylella is not available and efforts need to be focused on prevention, the use of resistant plant varieties, cultural/hygiene controls, and vector control. Xylella is currently present in the America’s, Europe, India, Iran, Lebanon, Taiwan and Turkey.
Xylella is responsible for a number of plant diseases with significant economic impact internationally. Examples include Pierce’s disease in grapes, Citrus variegated chlorosis, Almond leaf scorch and most recently Olive quick decline syndrome in Italy and France. The symptoms of these diseases vary depending upon the plant species affected but range from reduced vigour and crop yields, through to leaf scorching and death of the plant.
Australia is fortunate that Xylella is not currently present but its arrival could lead to significant economic impact. Likewise given that a number of hosts families are represented in native Australian species the bacteria could significantly impact upon our natural environment. Additionally for the nursery industry there is also evidence that the bacteria impacts upon amenity plantings as well, such as maples, oaks and elm through bacterial leaf scorch.
In light of recent international developments the Department of Agriculture and Water Resources has moved to alter its quarantine requirements to reduce the likelihood of entry of the bacterial plant pathogen Xylella fastidiosa and related Xylella species.
Changes to import requirements include:
- Nursery stock and plant material coming from countries or regions where Xylella occurs will need to be tested offshore and certified as free from Xylella by the government of the exporting country. If this certification is acceptable then the current import conditions for the plant species will apply.
- Material that does not meet this requirement will be held and tested in an Australian Government quarantine station for a minimum of 12 months
- An approved arrangement that ensures the health of plants will need to be in place for off-shore certification of nursery stock from high risk countries.
The Department will continue to review the emergency measures and these will be adjusted in the coming months as more information on the host range and spread of Xylella comes to light.
For more information on the changes to the impost conditions of Xylella hosts please refer to the Alerts posted on the Department of Agriculture and Water Resources BICON website here or refer to the individual import case requirements.