About Ceratocystis wilt
This wilt is caused by a fungus. There are many different strains of the fungus. We don't yet fully understand the host plants each strain may infect. We have one strain here in New Zealand. It only affects kūmara.
Global distribution of Ceratocystis wilt
Why this is a problem for New Zealand
Some strains of this fungus are aggressive and can attack many hosts. In Hawai'i, this fungus causes “rapid ōhi’a death”. The disease has killed large numbers of native Hawai’ian ōhi’a trees. Ōhi’a trees are closely related to iconic New Zealand native species of pōhutakawa and rātā.
A form of this fungus has affected whole kiwifruit orchards in Brazil, reducing yield and killing plants.
How different strains could get here
The fungus is most likely to get here on infected nursery stock. MPI has strict measures to stop it from getting here on all the known host plants, including myrtles, kiwifruit, stonefruit, and citrus.
MPI also has measures to stop other possible carriers (such as infected soil or wood products).
How to identify Ceratocystis wilt
Ceratocystis infections cause plants to wilt and collapse. The fungus multiplies in and blocks the water transport system. This stops the water moving through the plant. The signs are similar for many other wilt diseases.
- Mature ohi’a trees killed by rapid ohi’a death in Hawai’i – NPR website
- Kiwifruit affected by Ceratocystis wilt in Brazil – Kiwifruit Vine Health website
If you think you've found Ceratocystis wilt
- photograph the trees and symptoms
- note the location and any landmarks
- call 0800 80 99 66
Note: This information is a summary of this disease's global distribution and potential impacts on New Zealand.