Bacterial canker of kiwifruit
Pseudomonas syringae pv. actinidiae (PSA)
PSA is caused by the bacteria Pseudomonas syringae pv. actinidiae.
PSA disease is present in Japan, Korea, China, Italy, Argentina and New Zealand. There are different strains of PSA. Some are mild (like those detected in Victoria in 2011) and others are more aggressive. The effects of PSA depend on the strain type, the vine cultivar, and weather conditions.
What to look for:
The early signs of PSA are dark spots on leaves of vines (see image).
As the disease progresses symptoms include brown discoloration of buds, dark brown spots surrounded by yellow haloes on leaves, cankers with reddish exudate on twigs leaders and trunks and collapse of fruits. Infected plants can eventually die.
How is PSA spread?
Over short distances PSA can be spread by heavy rainfall, strong winds, mechanical transmission such as grafting and by animals.
Over long distances, PSA is spread by nursery stock. The PSA bacteria has also been found on pollen, but it is unclear whether pollen can cause infection. Laboratory tests have been unable to infect fruit – fruit is not considered to be a pathway for the introduction and establishment of PSA.
Are weeds affected? Yes!
PSA is also known to infect:
- Alternanthera philoxeroides (alligator weed)
- Paulownia tomentosa (paulownia)
- Setaria viridis (green foxtail)
Good practice weed management should be a priority for all growers to stop the spread of PSA.
When is the disease likely to occur?
Symptoms are likely to occur during wet and cool weather conditions. The bacteria may be present without symptoms during other conditions. In other countries symptoms are usually expressed during spring and autumn when favorable conditions are present.
If you suspect you have PSA
If you find symptoms that you suspect could be PSA please contact firstname.lastname@example.org
Download this information as factsheet (PDF - 307.8 KB) .