12 de diciembre de 2022

Fungus-eating fungus: coming to a myrtle near you?

Reports on iNaturalist and from scientists heading into the field tell us that the 2022-23 myrtle rust 'season' is in full swing. This time around, those with good eyesight or a hand lens/magnifying glass could lend researchers an extra hand by looking out for a fungus that feeds on myrtle rust - a species in the Sphaerellopsis genus. This organism is hard to spot but has been seen on myrtle rust-infected ramarama (Lophomyrtus bullata), rōhutu (Lophomyrtus obcordata) and on one of the climbing rātās (Metrosideros diffusa) in and around Taranaki and the Kaimai-Mamaku ranges. Is it more widespread? Scientists want to know! For more information, including images and instructions on how to make a report, see the story about this discovery on the Beyond Myrtle Rust website here.

No Sphaerellopsis on your myrtle rust? No problem - please continue to upload your images (they are still useful). Between 1 November 2021 and 10 June 2022, New Zealanders reported 827 new observations of myrtle rust on iNaturalist - up from 561 during the previous 12 months. In fact according to this story A. psidii (the fungus that causes myrtle rust) has become the most common fungi reported on iNaturalist in New Zealand. For more information about myrtle rust records made on iNaturalist last summer, see here. With all the images flowing onto iNaturalist already, we could top 1,000 this year. Not great news for our myrtle plants - but helpful for those looking out for them.

Publicado el diciembre 12, 2022 03:37 MAÑANA por reneejohansen reneejohansen | 0 comentarios | Deja un comentario

23 de agosto de 2022

Could invasive weed Syzygium smithii be about to join NZ's myrtle rust host list?

A recent find of myrtle rust on the invasive weed Syzygium smithii and reported on iNaturalist highlights that we may still see the disease on 'new' hosts, even five years after the fungal spores that cause it blew upon our fair shores. Curiously, even though Syzygium species are typically highly susceptible, this host is not on the MPI list of species known to be infected in New Zealand. It has been reported as a host on iNaturalist before, but MPI has not confirmed the host species. This needs to happen before the host list can be updated. It is not easy to identify the different Syzygium species present in NZ. For more information about them and how to tell them apart, see here. Syzygium smithii is listed on the National Pest Plant Accord meaning it is banned from distribution, propagation, and sale but it can still be found in gardens following historical plantings. MPI is following up on this recent report so we may soon see the plant added to the list of NZ hosts.

Over time, we can expect myrtle rust to further establish in New Zealand. This will see the 'spore load' (amount of spores in the air) continue to increase. This may mean new hosts become infected, and/or known hosts suffer from more severe infections. Strains not known to be present in New Zealand may also arrive, threatening hosts not susceptible to the current strain. If you think you have a record of infection on a new host in NZ, please let MPI know. If you are interested in whether the species may have been recorded as susceptible in other parts of the world, a global host list is available here (scroll down to find the list.) The new record of the disease on Syzygium smithii shows iNaturalist continues to be a valuable source of information about the spread of myrtle rust in New Zealand, so do continue to upload sightings.

Publicado el agosto 23, 2022 12:33 MAÑANA por reneejohansen reneejohansen | 1 comentario | Deja un comentario

28 de abril de 2022

Myrtle rust reaches the Chatham Islands

A conspicuous new record has appeared on the Myrtle Rust Reporter map - the first find on the Chatham Islands. The sharp-eyed and regular iNaturalist poster Lloyd Esler recorded the find. In doing so, he expanded the known range of the problematic fungus that causes myrtle rust, Austropuccinia psidii, by approximately 800 kilometres. There is, however, a twist to this tale - the fungus is occupying a weed. Said weed, Ugni molinae or Chliean guava, is good for making jam but is busy destroying sensitive ecosystems. Given the rapacious nature of this plant, and the lack of naturally occurring Myrtaceae on the islands, we may be looking at a very unusual situation whereby myrtle rust results in an overall environmental win. If you would like to learn more about this, and to hear researcher Peter de Lange talk about the find, check out these links:

https://www.rnz.co.nz/national/programmes/morningreport/audio/2018838950/myrtle-rust-found-on-the-chathams-but-it-s-not-all-bad-news

https://www.newstalkzb.co.nz/on-air/mike-hosking-breakfast/audio/peter-de-lange-beyond-myrtle-rust-programme-researcher-says-there-is-a-silver-lining-in-disease-found-on-chatham-islands/

https://www.scoop.co.nz/stories/AK2204/S00388/myrtle-rust-found-on-the-chatham-islands.htm

The far-flung nature of the disease had it reported from another island in April - Aotea (Great Barrier) near Auckland - this time on nursery pohutukawa. This disease loves nursery conditions - especially wet leaves. A reminder - if you want to raise vulnerable seedlings, it's best to find a way to water them without getting the leaves wet.

Publicado el abril 28, 2022 04:48 MAÑANA por reneejohansen reneejohansen | 1 comentario | Deja un comentario

23 de febrero de 2022

Myrtle rust can travel with nursery plants, and sneaky spores

A recent report of myrtle rust on Bartlett's rātā (Metrosideros bartlettii) plants shipped from a nursery reminds us that, sadly, the disease can travel and potentially be introduced to new places with nursery plants. It is possible that symptoms were not visible at the time the plants were packed. It's the time of year when myrtle rust is rife, especially with all the wet weather some of the country has been having keeping leaf surfaces moist while the temperature is warm, so do keep an eye on any new Myrtaceae foliage - whether the plant has recently arrived at your place, hangs out in a pot on the deck, or is established in the garden. Avoid encouraging new growth by keep the pruning shears in the shed for now.

I have heard from a gardener who was surprised that their pōhutukawa seedlings had myrtle rust, even though they were located in a greenhouse. Unfortunately the spores of the fungal pathogen are highly mobile and can easily sneak around. If you are raising Myrtaceae in a greenhouse, the key thing to remember is to keep the foliage dry - the fungal spores can not infect without water. Therefore, water very carefully and only at the base.

We now also have a record of pōhutukawa fruits being infected on a large mature tree at an Auckland park, adding to evidence that this species is being increasingly impacted by myrtle rust - also being shown by the records posted here. What's the number one thing you can do for our native taonga suffering from a rusty onslaught? Avoid planting exotic Myrtaceae, especially Syzygium species often sold as 'lilly pilly', and Lophomyrtus plants, in your garden. If they are already there - and especially if they are infected - plan to replace them with something not susceptible to myrtle rust.

Publicado el febrero 23, 2022 04:03 MAÑANA por reneejohansen reneejohansen | 2 comentarios | Deja un comentario

07 de diciembre de 2021

Myrtle rust taking off again

Recent increases in the number of myrtle rust reports on iNaturalist suggest the disease is, unfortunately, being helped by the warm wet conditions much of the country is now experiencing. November saw 188 observations, following just 27 in October and 23 in September. I am informed that exotic Myrtaceae hedges across Auckland are "lit up like Christmas trees" - and not in a good way! If you have one of these hedges, it would do our native trees a real favour if you could remove it - fewer spores blowing around = less chance of infection on native forest plants. And spores can travel a long way! It is also now best to water only at the base of myrtle plants in your garden (to keep the above-ground plant parts dry), and hold off until autumn before pruning and fertilising. This will reduce production of the new growth that is most vulnerable to myrtle rust. For more tips, and notes on reducing biosecurity risks when removing plants, see here for myrtle rust FAQs: https://www.landcareresearch.co.nz/discover-our-research/biosecurity/ecosystem-resilience/beyond-myrtle-rust/faq/

Meanwhile, myrtle rust continues to spread through our native forests. A recent record of myrtle rust on Lophomyrtus in Hokitika is notable - the first from the west coast of the South Island this season. If you are out and about, especially in native forest areas, do keep an eye out for myrtle rust and keep putting up your pictures. Scientists and land managers appreciate this.

Publicado el diciembre 7, 2021 04:52 MAÑANA por reneejohansen reneejohansen | 2 comentarios | Deja un comentario

30 de agosto de 2021

Where and when might you spot myrtle rust? Find out in a recent webinar

Myrtle rust observations recorded on iNaturalist throughout winter suggest that symptoms vary by host and by area. This reminds us of the importance of host susceptibility and the environment (in this case, mostly climate) to disease development. Yellow pustules tell us the fungus causing myrtle rust has produced spores on the host, and these have been seen right throughout winter in some parts of New Zealand. However, it’s not just the appearance of the spores that matters – the time it took for them to appear post-infection – the ‘latent period’ – is key to understanding disease spread. If you would like to learn more about myrtle rust epidemiology, and particularly about disease spread in NZ and what we might see in the future, check out the webinar by plant pathologist Rob Beresford now available for viewing here:

https://www.landcareresearch.co.nz/discover-our-research/biosecurity/ecosystem-resilience/beyond-myrtle-rust/webinar-series/

And when you are out of the house on that lockdown stroll, tinkering in the garden, or lucky enough to be further afield on a hike, keep your eyes open for myrtle rust symptoms to photograph - your records matter.

Publicado el agosto 30, 2021 03:04 MAÑANA por reneejohansen reneejohansen | 0 comentarios | Deja un comentario

05 de julio de 2021

iNaturalist reporting summary shows value of reporting finds

As the mercury drops around the country, our myrtles should finally be enjoying some respite from myrtle rust. If you do see symptoms though - particularly of telltale yellow spores indicating an active infection - put your pictures up. This article, reporting on finds logged on iNaturalist throughout the last 'season,' describes how your records inform land managers, help researchers, and have even attracted media attention:

https://www.landcareresearch.co.nz/discover-our-research/biosecurity/ecosystem-resilience/beyond-myrtle-rust/news/myrtle-rust-inaturalist-reports-from-last-season/.

Over 500 new reports have been made since last November.

While myrtle rust is lying low, now is the time to think about pruning your myrtles so new growth is less likely to be infected. You might also want to think about replacing vulnerable myrtles in your garden, especially non-native plants like lilly pillys. If we can keep infections down in gardens, spore numbers in the environment will reduce, and native plants in the bush will have a reduced chance of infection. For other tips, and answers to questions about myrtle rust you might have, see here:

https://www.landcareresearch.co.nz/discover-our-research/biosecurity/ecosystem-resilience/beyond-myrtle-rust/faq/

Publicado el julio 5, 2021 11:01 TARDE por reneejohansen reneejohansen | 2 comentarios | Deja un comentario

18 de mayo de 2021

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/

Publicado el mayo 18, 2021 03:40 MAÑANA por reneejohansen reneejohansen | 3 comentarios | Deja un comentario

14 de enero de 2021

Myrtle rust: coming to a pōhutukawa near you?

Warmth, a bit of rain, and humidity – unfortunately all the ingredients are now present in many places for myrtle rust to be ravaging myrtle plants. Seen some yellow spores? Don’t touch them – snap them – and upload. Got some clear pictures of the host plant? Even better – these can help our experts confirm the symptoms indicate myrtle rust. The pictures of rohutu and ramarama (bubble leaf) keep coming – testament to the extreme vulnerability of these species to myrtle rust. Keep it up but also – it would be great if people could keep a special look out for pōhutukawa right now. Unfortunately reports are trickling in that even mature trees are now being impacted – especially on the ‘epicormic’ growth (new growth coming from old branches.) More information about where this is happening would be great – and whether this (and all) myrtle species are sporting spores on fruits and flowers. Leaves are commonly photographed – but don’t forget to check reproductive structures as well if they are present.

Publicado el enero 14, 2021 03:51 MAÑANA por reneejohansen reneejohansen | 0 comentarios | Deja un comentario

04 de diciembre de 2020

Myrtle rust season is upon us

As we come into the myrtle rust season (this disease thrives in warm, wet conditions), now is the time to be looking out for yellow spores. Researchers studying myrtle rust in the field are getting their summer field work underway, and you can help by keeping your eyes peeled as well. Spores are popping up across Auckland (thanks to everyone uploading pictures of these) and pustules have recently been seen by scientists in Taranaki. Thanks to those who have also reported the disease in other areas including Northland, Rotorua, Coromandel and on the East Cape. Given the local climate, these areas are likely hot spots for the disease, and further observations will help confirm this. Seen it somewhere else? Upload your pictures and help us understand what's going on out there.

Publicado el diciembre 4, 2020 02:47 MAÑANA por reneejohansen reneejohansen | 7 comentarios | Deja un comentario