No myrtle rust in winter
‘‘But what we do expect that areas we don't know about will show themselves come spring.’’
The myrtle rust threat has abated in the Waikato, but the disease could be lying dormant over winter.
A second Waikato case of the rust-coloured fungal disease which attacks native trees was found in a Te Kuiti nursery in May.
Ministry for Primary Industries ( MPI) has confirmed no other affected plants have been found in the Waikato or Coromandel.
MPI response manager Dr Catherine Duthie said the rust may begin to spread during the coming spring and summer.
‘‘Given that it’s winter time and the symptoms are suppressed during the cold weather … once the weather warms up, things start sporulating and the spores get blown by the wind - we will see spread at that point,’’ she said.
The windborne disease is thought to have blown over from Australia and continues to heavily affect north Taranaki and Te Puke, where MPI continues to identify new cases almost daily.
‘‘None of the evidence, in terms of the age of the infections that we’re seeing, indicates that there’s been any spread from that initial distribution of infections,’’ Duthie said.
The Department of Conservation (DOC) continues to conduct extensive surveillance for the disease in the Coromandel, targeting specific areas based on wind pattern modelling. No rust has been found.
DOC has also been collecting and preserving seeds from the different regional species of affected plants throughout the country.
If no further spread is identified over spring and summer, it may be possible to eliminate the rust from local regions, Duthie said.
‘‘But what we do expect that areas we don’t know about will show themselves come spring.’’
Myrtle rust attacks plants in the myrtle family, including pohutukawa, rata, manuka, gum, bottlebrush and feijoa.
The disease damages foliage, and exposes a plant to secondary disease.
Kawhia residents expressed concern for a grove of scared pohutukawa which line the coastal town’s shores in June.
Ngati Mahuta kaumatua Tom Moke commended the Otorohanga District Council’s response.
Council workers have checked the ancient Tangi-tekorowhiti tree weekly, and the community was now informed and vigilant for rust.
‘‘There’s been no sign of it ... it may have been in Te Kuiti, but it’s certainly not out here.
‘‘It must be hard for it to spread in wintertime, so summertime will tell.’’
No more cases of myrtle rust have been found in the Waikato since May, but the disease may be lying dormant. Dr Catherine Duthie