Pierce's disease and glassy winged sharpshooter

Have you seen symptoms of Pierce´s disease or the glassy winged sharpshooter?

In Queensland, Pierce’s disease (Xylella fastidiosa) and glassy winged sharpshooter (Homalodisca coagulata) are both listed as prohibited matter under the Biosecurity Act 2014.

Be on the lookout and report them to Biosecurity Queensland.

Early detection and reporting are the key elements in controlling the pest.

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  • Advanced symptoms of Pierce's disease on a merlot grapevine leaf
    Advanced symptoms of Pierce's disease on a merlot grapevine leaf
  • Symptoms of leaf scalding caused by Pierce's disease on Chardonnay grapevine leaves
    Symptoms of leaf scalding caused by Pierce's disease on Chardonnay grapevine leaves
  • Photo of a Glassy winged sharpshooter
    Photo of a Glassy winged sharpshooter

General information

Pierce's disease of grapevine is an exotic bacterial disease caused by a strain of the bacterium, Xylella fastidiosa. Xylella fastidiosa infects more than 100 plant species, including many perennial fruit crops and forest trees. Crops of particular concern in Queensland are grapes (Vitis vinifera), stonefruit, citrus, coffee, mulberry and pear.

Pierce's disease is spread by a number of insect vectors. The most efficient vector is the glassy winged sharpshooter, Homolodisca coagulata. Pierce's disease occurs in North America (southern states of the United States) and Central America (Mexico). Currently, Pierce's disease and the glassy winged sharpshooter are not known to be present in Australia.

Overview

Hosts

Pierce's disease is one of the most significant exotic pest threats to the Queensland grape-growing industry. Xylella fastidiosa (the causal bacterium) is also a significant threat to many other fruit crops, including plums, peaches, nectarines, pears, citrus and coffee.

More than 150 other species of plants (including pasture crops such as lucerne) can host the glassy winged sharpshooter. Many of these are also hosts of the Pierce's disease strain of Xylella fastidiosa.

Symptoms and damage

Pierce's disease symptoms are very similar to those caused by water stress, as the disease blocks the water conducting tissues (the xylem) of the host plant.

The disease severely limits fruit production, with leaf scorching and wilting (Figure 1), leading to shrivelled unsaleable fruit.  These effects are so strong they can kill Vitis vinifera vines (commercial grapevines) within 1-4 years.

Look for necrotic leaf margins (Figures 2 and 3) and shrivelled fruit clusters, petioles attached to the cane, and wood on new canes maturing irregularly, producing patches of green surrounded by mature brown bark.

If native insects could vector the disease or if it arrived with the glassy winged sharpshooter, it would have a severe impact on vine productivity and possibly lead to the death of whole vineyards

Spread

Xylem feeding insects, such as glassy winged sharpshooters, can spread Pierce's disease from vineyard to vineyard. Although the glassy winged sharpshooter is not known to be present in Australia, there are other xylem feeding insects here that could have a capacity to spread the disease.

Pierce's disease is prevalent in areas of North America (California and Florida) that experience mild winters, which may indicate that many Australian production areas could be favourable for its development.

How is the disease controlled?

Control or exclusion of vector insects must be practised to reduce the incidence of Pierce's disease in vineyard areas. In the United States, vineyards in close proximity to glassy winged sharpshooter habitats are most at risk. Glassy winged sharpshooters flourish in a wide variety of habitats, particularly where citrus, avocado, eucalyptus and oleander are growing, as well as in residential, park and riverine (stream-side) locations. Growers monitor these habitats for glassy winged sharpshooters, using sticky traps to warn of their movement into vineyards, and apply insecticides accordingly.

There is no cure for Pierce's disease, but infected arms or whole plants can be removed to prevent infection of adjoining vines.

In the United States, the movement of items capable of distributing Pierce's disease vectors (such as glassy winged sharpshooters) are strictly regulated. In particular, nursery plants and fresh fruit cartons(e.g. citrus or grape) are effective ways to transport these insects over long distances.

Last updated 02 September 2011