About black rot
This is a fungus that causes diseases on grapes and some ornamental plants. It's native to North America and parts of Europe.
Global distribution of black rot
Why this is a problem for New Zealand
This fungus can cause up to 80% loss of a grape crop. It can spoil the taste of wine if infected grapes mix with healthy ones.
It's quite hardy and can survive harsh conditions in canes, leaves, the vine, or the ground.
How could it get here
The fungus could come in as a visible powder (spores) on:
- fruit (grapes)
Whenever travelling to New Zealand, always declare any food or fruit in your luggage. If you fail to do so, you could face a $400 fine.
Where will I find it
Black rot is more likely to establish in the North Island.
How to identify black rot
You will see small brown circular spots on young grape leaves (older leaves can resist the rot). The symptoms on leaves can be confused with other fungi.
Black rot infects grapes when they're still green. You will see light brown spots that become dark brown. Eventually, the spots cover the whole fruit.
Right: Symptoms of black rot on a grape stem. Image: CC 3.0 by Clemson University – USDA Cooperative Extension Slide Series
If you find black rot
- photograph it
- collect a sample
- call 0800 80 99 66
Note: This information is a summary of this disease's global distribution and potential impacts to New Zealand.