Important update on myrtle rust – 26 September

27 September 2017

HELP CONTROL MYRTLE RUST

There are now 121 confirmed finds of myrtle rust: 4 sites in Northland, 78 sites in Taranaki, 33 in Bay of Plenty and 6 sites in Waikato.

Unfortunately myrtle rust continues to spread, and the fungus has now been found on two properties in the Otorohanga township – in both cases on a single ramarama tree. The two properties do not have a connection with nurseries or other infected properties in Taranaki.  It would appear these are infections that have occurred through wind contamination.

The Ministry for Primary Industries has introduced legal restrictions on the movement of myrtle species plants and green waste out of the Taranaki region.  The restrictions are set out in a Controlled Area Notice. Full information about the Controlled Area, including the notice itself and a map, can be found here.  

To date, the rust has been found on pōhutukawa, Lophomyrtus bullata (Ramarama), eucalyptus, mānuka and Syzygium smithii. It has not been observed on feijoa.

Please read the below for information on the latest situation, plus some important advice to those of you planning planting events, and for nurseries.

The Project Crimson Trust is seriously concerned for the impact of myrtle rust on our Metrosideros species; there’s no way of predicting how our native plants will cope with this fungal disease. We are asking for your help as New Zealand faces a major biosecurity threat to native plants with the discovery of myrtle rust. The below information is particularly important to anyone who might be either growing plants or planning planting days.

 What you need to know

  • MPI has introduced a Controlled Area which extends 10km from the known infected areas in Waitara, Taranaki. This means it is illegal to move plants (including trees) or plant material (such as garden waste, clippings, feijoa and guava fruit) from the myrtle family out of this area. You can still buy and plant these species inside the Controlled Area.
  • Check any Myrtaceae plants on your property for symptoms of myrtle rust (some common examples of these are pōhutukawa, mānuka, bottlebrush, feijoa, ramarama, blue gum)
  • For the first time in Project Crimson’s 27 year history, the Trust has temporarily halted the planting and distributing of any pohutukawa or rata trees and is asking New Zealanders to follow their lead. Says Project Crimson Trustee, Dr Gordon Hosking “We are asking Kiwis to help by not planting pohutukawa or rata trees for the remainder of the 2017 planting season (this varies by region but is typically until mid-Spring). Because myrtle rust becomes dormant over winter infected plants may not show symptoms until spring so this gives us more time to understand the impact myrtle rust is going to have on pohutukawa and rata, and also prevent people from unwittingly spreading this serious fungal disease further.”
  • MPI advise not to plant any myrtle species in the New Plymouth, Waitara, Kerikeri, Te Kuiti or Te Puke areas.
  • Myrtle rust symptoms may not develop on infected host plants in the current winter conditions (myrtle rust prefers temperatures over 10°C), and therefore symptomless plants may be infected with myrtle rust. Movement of plants could unwittingly move infected plants to new locations, spreading myrtle rust further. By late spring, the health of susceptible plants will be much clearer.
  • Project Crimson urges New Zealanders to plant other native trees this year and are reminding people that the halt on planting pohutukawa and rata is temporary. “We urge Kiwis to remain committed to planting natives this year, but simply to avoid pohutukawa or rata to give us some time to understand this disease, we really hope to see New Zealanders back out planting pohutukawa next year. With a warming climate and our native birds in decline there has never been a more important time for us to be planting native trees.  Please keep planting as many other native trees as you can this year, we just ask you to avoid pohutukawa and rata for the next few months so we can try to protect them for future generations” says Dr Hosking.
  • If you suspect myrtle rust, please take a photo and report to MPI (0800 80 99 66) and don’t move any plants, produce or gardening equipment offsite until you hear back from MPI.
  • While most infections are on seedlings, one of the most recent detections was an extensive outbreak in a very established pōhutukawa hedge belt in Taranaki. The hedge has been safely removed and destroyed.
  • Staff from MPI, DOC and the Northland, Taranaki and Waikato local and regional councils are working on carrying out surveillance around confirmed properties, setting up controls and applying fungicide treatment.
  • To secure the long term future of taonga Myrtaceae species, seed collection work is in progress involving manawhenua, to conserve the biodiversity of native Myrtaceae in New Zealand. As a result DOC is leading the collection of seed for seed banking. This includes pohutukawa,

There are 2 main reasons why the rust is being found in plant nurseries.

Myrtle rust

Growing conditions there are ideal for the fungus with many vulnerable young plants in sheltered, warm and damp environments. In addition, there has been a large amount of communication with the nursery industry and growers have been particularly vigilant in checking their plants.

Identifying myrtle rust

Yellow bumps and brown patches typical of myrtle rust

Myrtle rust only affects plants in the myrtle family.  It generally attacks soft, new growth, including leaf surfaces, shoots, buds, flowers, and fruit. Symptoms to look out for on myrtle plants are:

  • bright yellow powdery eruptions appearing on the underside of the leaf (young infection)
  • bright yellow powdery eruptions on both sides of the leaf (mature infection)
  • brown/grey rust pustules (older spores) on older lesions.
  • Some leaves may become buckled or twisted and die off.

 The THREAT

The disease could be on any plants from an infected area taken to a revegetation site. It can also be carried on clothing or vehicles. Myrtle rust spores are microscopic and can easily spread across large distances by wind, or via insects, birds, people, or machinery.

If it becomes widespread it will impact all of New Zealand’s Myrtaceae to some degree and we are likely to lose some native species in their natural state. Ecological integrity will be compromised in places where myrtles are a dominant species. It is also likely to affect commercial activities (e.g. manuka honey industry), tourism, recreation and landscape values.

It is very important community planting groups, volunteers and all those who go into the forest follow certain hygiene protocols to restrict the spread of the wind-borne disease. Revegetation work is a potential vector for spreading myrtle rust. People doing voluntary conservation work of any type, could inadvertently spread the disease.

Community Group Action

If you are growing plants

  • Commercial plant nurseries are required by MPI to comply with NZPPI protocols of plant hygiene. Other plant nurseries are requested to comply with these protocols so the next link in the chain is where the plants go to from the nurseries.
  • At this time, DOC is encouraging community groups to adopt the same protocols to lower the possibility of any further spread of myrtle rust and to keep an eye out for myrtle rust.

If you are planning to plant

  • Project Crimson is asking people to consider not planting pohutukawa and rata but to plant other native plant species this year.  It is advisable to ensure the nursery of origin has been adhering to the NZPPI hygiene protocols and you keep a record of number of plants by species, their origin and planting location, as these plants can still be a vector.
  • Please follow this advice:
    • Seek advice from experts when sourcing plants, e.g. from your nursery or supplier
    • Know where your plants come from, keep a record of where you’ve planted them
    • Keep alert for signs of myrtle rust. Myrtle rust becomes dormant over winter and infected plants may not show symptoms until spring
    • Check new plantings as the weather warms up
    • Myrtle rust primarily affects new plant growth including young shoots, flower buds, leaf surfaces and fruit
    • More detailed information about nursery and plant hygiene is at NZ Plant Producers Inc website.

Hygiene Recommendations for Community Groups

  • Check any myrtaceae plants for symptoms of myrtle rust
  • If you are bringing myrtaceae plants in, check the site the plants are coming from has been surveyed for symptoms of myrtle rust.
  • If you suspect myrtle rust, please take a photo and report to MPI (0800 80 99 66). Don’t move any plants, produce or gardening equipment offsite until you hear back from MPI.

If you find anything suspicious

1. Do not move the plants from the site or your truck.

2. Take photos of the suspected myrtle rust and the whole plant.

3. Do not attempt to touch or collect samples as this may increase the spread of this disease.

4. If possible, isolate the plants with an igloo-hoop-like plastic cover.

5. Call MPI’s exotic pests and diseases hotline on 0800 80 99 66.

More information

Please feel free to share this information with anyone you feel will be interested. We’ll provide further updates as they come to hand if the situation changes, but please follow us on Facebook for more frequent updates.