Killer disease found on ramarama in Kaiti
Myrtle rust has arrived in Gisborne City, with the recent discovery of the disease on ramarama hedges at two properties in Kaiti.
“The trees are not smothered by the disease, but it is present,” Gisborne District Council principal scientist Dr Murry Cave said.
“Ever since myrtle rust was detected in New Zealand in 2017, we have been monitoring and responding to public queries.
“From increasing reports in Tairawhiti it now appears to be widespread, which is very disappointing, with wild plants infected on the East Cape.
“We will investigate if there is any present in the Motu Scenic Reserve.”
Dr Cave said it was inevitable that the disease would reach Tairawhiti, as it was believed microscopic spores had blown over from Australia or New Caledonia and it had spread rapidly across the North Island and parts of the South Island.
The disease affects familiar and much loved New Zealand plants in the myrtle family.
New Zealand has a variety of native plants that belong to this family including pohutukawa, manuka, kanuka, rata, swamp maire and ramarama.
Other plants in the Myrtaceae family include the introduced fruit species feijoa and guava and commercially grown species such as eucalyptus.
Because myrtle rust is now widespread, since July 2019 the emphasis has shifted from eradication to understanding and controlling the disease.
“Members of the public who believe they have spotted an infestation can contact the local DoC office or the council,” Dr Cave said
“Once established on a host tree or shrub, it destroys new growth and soft tissues, eventually killing the plant. So it's not to be dismissed lightly.”
Home gardeners are advised not to remove plants, as that will spread spores.
They can treat affected plants with commercially available products, although they will need long-term treatment.
“The disease poses a significant threat to wild and some agricultural species,” Dr Cave said.
When a plant becomes infected with myrtle rust, the disease affects the young, soft, actively growing leaves, shoot tips and young stems.
At the very early stages symptoms are invisible to the naked eye.
Even in the later stages of infection myrtle rust can be very difficult to detect, as some symptoms can look similar to insect or other types of damage.
The first visible symptoms are powdery, bright yellow or orange-yellow pustules that develop on leaves, tips and stems.
The pustules can progress into wounds on the plant and may cause leaves and shoots to become misshapen or disfigured and die off.
The disease can cause deformed leaves, heavy leaf loss from branches, damaged fruits, canopy dieback, stunted plant growth, and eventually may lead to plant death.