Rust risk to manuka honey low

Myrtle rust. Photo: Supplied

The overall risk of myrtle rust to the manuka honey industry is low, honey producer Comvita says.

The company announced to the NZX yesterday it was basing its statement on information it had been collating about the ongoing myrtle rust situation.

Although it was early days in terms of analysing the effect of myrtle rust on manuka plants in New Zealand, the information collated was consistent with what was being seen in this country, chief executive Scott Coulter said.

Myrtle rust had not been found on manuka in the wild. It had been found in nurseries and domestic environments, including the one infection found on a manuka plant which was in a nursery.

Nurseries tended to have young plants in warmer and more humid environments than natural sites, and they were generally more susceptible to fungal infections, he said.

Myrtle rust spore production was stimulated in the warmer months when humidity was high and when leaves were wet for six hours or more.

Current scientific knowledge indicated temperatures of 15degC to 25degC were required for the rust to complete its life cycle, otherwise the fungus remained dormant.

However, Comvita was taking the rust incursion seriously and was undertaking several initiatives as part of its ongoing response to the situation, Mr Coulter said.

They included: standard operating procedures on how to identify, assess and report the condition; educating Comvita beekeepers to recognise and report the rust, although there was no sight of it in the field so far; all Comvita nursery stock destined for extensive plantings was being regularly inspected; ensuring a treatment regime was applied before any plants were distributed from nurseries; investing in mobile hive units so hives could be moved and relocated should myrtle rust be detected; and working with scientists in New Zealand to apply the lessons from Australia and model potential outcomes in the local environment.