Destructive Fungus Threatens Manuka Honey

The Manuka honey industry has had much success in the decades since the Manuka bush was considered a mere weed to be plucked from the fields in mainland New Zealand. It’s said to be an industry currently worth 300 million dollars, with the potential to be worth 1.2 billion dollars in the future, says Unique Manuka Honey Factor Association spokesman John Rawcliffe. In the face of that potential, however, the lucrative New Zealand industry must face a new obstacle beyond the enigmatic colony collapse disorder (CCD)—an invasive fungus called myrtle rust.

Myrtle Rust

The invasive fungus, never before seen on New Zealand’s mainland soil, has been discovered in a Kerikeri tree nursery on five young pohutukawa seedlings, a species that may be at serious risk should the myrtle rust take hold on New Zealand’s mainland. “[Myrtle rust] tends to attack the leaves, and it actually shrivels up the leaves of the plant, and they wither and die,” said Andrea Byrom of the Biological Heritage Science Challenge. "It's impacted on a number of species in Australia, particularly native species, so the ti tree they call it, similar to our Manuka." Other native plants, such as kanuka and rata, could also be in danger as well as exotic plants like eucalyptus, guava, and feijoa.

The infected seedlings were discovered on May 2, two months after a full grown pohutukawa tree was discovered to be infected with myrtle rust on Raoul Island, which lays north of mainland New Zealand in the Kermadecs. “We get a prevailing northwesterly wind across the Tasman [Sea], and so things like this rust…it’s got spores that travel on the wind, so it’s not surprising that eventually it might have got here. It’s just a shame that it has arrived,” Byrom said.

Containment

A biosecurity team is working to keep the myrtle rust contained to the Kerikeri nursey. According to Nathan Guy, who serves as New Zealand’s minister for primary industries, "We've stood up a response there. Effectively, the nursery is in lockdown, [and] it is currently being sprayed." Conservation lands are also being scoured for any traces of infection, with the hope being that the myrtle rust has not gotten far. "The issue with this particular fungus is that from the time it is infecting a plant, it could take between three and five weeks for that infection to become visible," Maggie Barry, who serves as conservation minister, said.

According to Guy, myrtle rust is notoriously hard to eradicate, based on the experiences of other countries, to the point that none have been truly successful in disposing of it. The most that can be done is contain the fungus while New Zealand citizens actively participate in tracking any further infections and then informing the Ministry for Primary Industries. Hopefully, neither the Manuka honey industry nor New Zealand will suffer greatly as a result of this invasive fungus.