It's getting colder - but myrtle rust is still around

While warm nights with damp leaves provide the perfect conditions for myrtle rust to develop on susceptible hosts, records popping up on iNaturalist from around the country suggest the troublesome fungus driving the disease is still active even as the weather cools down. Most reports are still being made from warmer parts of the North Island, but iNaturalist members in Ohakune and Christchurch have spotted the telltale symptoms of yellow pustules under leaves in the last few weeks. The Christchurch record is particularly concerning, given it suggests the first known infection there on a plant that was not recently introduced to a garden from another region. The source of the infection is not yet known. Lophomyrtus records are increasingly being joined by those from other species, especially pōhutukawa. One notable record from a host not yet commonly recorded, snapped near the Auckland Museum, is from a very ill Crimson rātā (Metrosideros carminea). With land managers and scientists keeping an eye on iNaturalist for new records, do post the host plant name if you can ID it along with pictures of the plant, there is interest in the host species as well as symptoms and locations. All this myrtle rust activity means it's probably best to wait a bit longer before pruning your trees (the new growth will be susceptible), and to ensure any sprinklers in gardens are not resulting in wet leaves on myrtle plants, especially overnight. For a quick guide to myrtle rust, including tips on plant removal, check out the FAQs on the Beyond Myrtle Rust research programme website: https://www.landcareresearch.co.nz/discover-our-research/biosecurity/ecosystem-resilience/beyond-myrtle-rust/faq/

Posted on May 18, 2021 03:40 AM by reneejohansen