Friday, July 21, 2017
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Myrtle rust low risk to honey

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Myrtle rust is believed to be a low risk to New Zealand’s growing manuka honey industry, says Comvita CEO Scott Coulter.

New Zealand Manuka honey is produced from exclusively from leptospermum scoparium, which is the only leptospermum variety found in New Zealand.

Manuka is also found in Tasmania and is part of a large family of leptospermums found in Australia.

“Because of this Tasmania is particularly relevant to our Manuka industry as it has similar varieties and environmental conditions as New Zealand,” says Scott.

Comvita’s Australian joint venture partner Capilano and apiary businesses in Tasmania have had no reports of myrtle rust being found in Manuka since the fungus was discovered in mainland Australia in 2010. And Tasmania in 2015.

“There has been no impact from myrtle rust on their honey production,” says Scott.

“We have also been communicating with the Tasmania Government agency the Department of Primary Industries Parks Water and Environment, which has not detected myrtle rust in the leptospermum species in Tasmania since its incursion.

“While it is in the early days in terms of analyzing the effect of myrtle rust on Manuka plants in New Zealand this information is consistent with what we are seeing here. Myrtle rust hasn’t been found on Manuka plants in the wild and so far has only been found in plant nurseries and domestic environments.”

One infected Manuka plant has been found in a nursery, says Scott.

Plant nurseries tend to have young plants in warmer and more humid environments than natural sites and are thus more susceptible to fungal infections.

Comvita is still taking the threat seriously and is introducing some initiatives:

  • Standard operating procedures on how to identify assess and report the condition,
  • Educating beekeepers to recognise and report myrtle rust
  • All Comvita stock destined for extensive plantings is being regularly inspected,
  • Ensuring a treatment regime is applied before any plants are distributed from nurseries,
  • Investing in mobile hive units so hives can be moved and relocated should myrtle rust be detected,
  • Investigate ways to introduce resistance to Manuka plant breeding programme across the plant varieties Comvita has developed.

Meanwhile, the Ministry for Primary Industries and Department of Conservation are introducing legal restrictions on the movement of myrtle species plants and green waste out of an area of the Taranaki region. 

MPI’s Myrtle Rust Response Incident Controller David Yard says to help control any spread of myrtle rust from the most infected area around Waitara, MPI has imposed a Controlled Area extending 10km out from the known infected properties. 

"It is illegal to move any plants or trees belonging to the myrtle family and any garden waste, fruit (feijoa or guava) or prunings from those plants out of this area," says David.

Myrtle rust symptoms are suppressed during the cold winter months, says David. And it’s proving difficult to get a good measure of exactly where the disease is present and the scale of the outbreak. 

"We could be dealing with an extensive outbreak, but there remains some possibility we may only have a small level of infection that could ultimately be eradicated.

"Until the weather warms up and any infection present becomes much more visible, we need to do everything possible to contain and destroy it in the areas we know about.

"Come spring, if we find it is limited to the current known areas, we’ll have the best possible chance to get rid of it from New Zealand."

Myrtle rust affects only plants in the myrtle family which includes pohutukawa, manuka, rata, ramarama, Lilly Pilly, eucalyptus (gum trees) and feijoa. 

"We encourage Taranaki residents to support us in this important job by not moving myrtle species plants, fruit or myrtle green waste out of the specified Controlled Area. Garden waste should be disposed of responsibly within the Controlled Area – for example at the Waitara transfer station or the New Plymouth landfill. Myrtle family plants can still be bought and planted within the zone."

Taranaki is the focus of the effort, even though myrtle rust has been found in other regions. Two small Northland and Te Kuiti infections have been managed and there has been no further sign of the disease in those areas. 

The rust has also been found on a small number of properties in Te Puke in the Bay of Plenty and work is still underway to determine the scale of the situation there.

"We encourage people to keep looking out for signs of myrtle rust and telling us about it. Knowing where the disease is and treating it gives us the best chance of protecting some of our treasured plants into the future."

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