Rapid response to myrtle rust
Myrtle rust, an invasive fungal disease, affects plants in the myrtle family such as pōhutukawa, mānuka, rātā, ramarama, eucalyptus, and feijoa.
To prepare for the possibility of myrtle rust getting into New Zealand, in 2014 we developed a fast and sensitive DNA-based test for the disease. When myrtle rust did arrive in New Zealand in 2017, this test was important in confirming suspected cases. During the following response to the disease, the test has allowed fast and confident diagnosis of myrtle rust.
We've also developed a DNA barcode database for myrtle family species, enabling us to confirm myrtle rust host plants at species or even hybrid level.
Over a 14-month period, our laboratory:
- processed over 3,800 notifications from the public and survey teams
- identified myrtle rust from nearly 1,500 samples.
Now that myrtle rust is established in New Zealand, we're focusing on reducing its risk through long-term pest management.
Looking for stink bugs
The brown marmorated stink bug (BMSB) is one of the world's worst invasive pests. Overseas, it can cause extensive damage to fruiting crops and is a major nuisance in urban areas, gathering in their thousands in homes during autumn.
PHEL entomologists play a significant role in keeping watch for this unwanted pest. An awareness programme generates hundreds of notifications from the public and industry each season. Most of these are screened by PHEL entomologists.
Over the last 3 seasons, we've screened more than 2,100 suspected BMSB cases.
Helping diagnose pests and diseases overseas
The International Plant Protection Convention (IPPC) is responsible for improving plant health worldwide. Our internationally recognised scientists are on the IPPC panel that develops diagnostic methods for pests and diseases that affect international trade.
Many of the tests developed at PHEL have been included in IPPC standards — including tests for fire blight, Pierce's disease in grapes, and myrtle rust.
International diagnostics training
PHEL has been actively working with Pacific nation partners, planning and delivering training to help develop their ability to identify and diagnose pests and diseases.
We've developed and delivered successful training programmes in Fiji and the Cook Islands.
A good end-point for avocados
Our virology team has worked with NZ Avocado to develop a testing method for their high health scheme which assures the health of avocado nursery plants.
The high health scheme includes testing for avocado sunblotch viroid (ASBVd) – a virus-like pathogen which causes deformity and streaks or blotching on avocados, making them unmarketable.
For many years, the preferred way to test for ASBVd in New Zealand was to test mother trees. But it can be impractical and uneconomical to test source trees from hundreds of orchards across the country.
An alternative was proposed to test trees after propagation rather than mother trees – a method known as end-point testing. Technical questions had to be answered before the avocado industry could be confident this was an acceptable alternative.
Many years of work on ASBVd by the United States Department of Agriculture (USDA), and more recent work by the virology team at PHEL answered these questions.
We've shown sensitive and robust detection of ASBVd from as little as one infected leaf in 100 leaves, using a real-time Polymerase Chain Reaction (PCR) method.
End-point testing is now included as an option in the high health scheme.
