scholarly journals Evaluating the efficacy of potential fungicide-adjuvant combinations for control of myrtle rust in New Zealand

2021 ◽  
Author(s):  
Kwasi Adusei-Fosu ◽  
Carol A. Rolando ◽  
Brian Richardson ◽  
Rebecca van Leeuwen ◽  
Robyn Gaskin ◽  
...  
Keyword(s):  
New Zealand ◽  
Leaf Surface ◽  
Post Inoculation ◽  
Myrtle Rust ◽  
Good Surface ◽  
Spray Inoculation ◽  
Leaf Surfaces ◽  
Austropuccinia Psidii ◽  
Tea Extract

AbstractMyrtle rust is a serious fungal disease caused by Austropuccinia psidii affecting a number of Myrtaceae species in New Zealand and elsewhere. Control with fungicides or biologicals provides a mechanism to reduce the build-up of inoculum in the short-term while other strategies are being developed or deployed for long-term management. This study evaluated the efficacy of fungicides for control of myrtle rust under controlled conditions and identified adjuvants that would promote spreading of fungicidal active ingredients across the leaf surface. The spread of fungicide on detached M. excelsa leaves was assessed by applying three different adjuvants in combination with seven fungicides. Subsequently, M. excelsa plants were treated with three fungicides/mixes, (azoxystrobin + epoxiconazole, triademinol or a natural tea-extract) at a single rate followed by inoculation with A. psidii urediniospores on day 0, 7, 14 or 21 days after spraying. The response to infection in M. excelsa plants based on different inoculation timings at days 0, 7 and 21 significantly differed among fungicide treatments. The fungicide azoxystrobin + epoxiconazole was the most effective with infections significantly lower on the adaxial leaf surface than abaxial, despite good surface coverage of fungicide being achieved on both leaf surfaces. There were significant differences among fungicides based on the proportion of infected leaves on M. excelsa plants. Day 21 post-spray inoculation indicated a significant interaction between inoculation time and fungicide on leaf disease ratings. However, this was not the case at either 28 or 35 days post-inoculation. This research contributes to fungicide options for myrtle rust control in New Zealand.

scholarly journals New Zealand indigenous Myrtaceae in foreign botanic gardens: testing the sentinel plant concept for biosecurity risk assessment

2021 ◽  
Vol 74 (1) ◽  
pp. 1-9
Author(s):  
Kirsty S.H. Boyd-Wilson ◽  
M. Virginia Marroni ◽  
Mark R. McNeill ◽  
David A.J. Teulon
Keyword(s):  
Risk Assessment ◽  
New Zealand ◽  
Invasive Alien Species ◽  
The United States ◽  
Botanic Gardens ◽  
Indigenous Plants ◽  
Myrtle Rust ◽  
Potential Pest ◽  
Austropuccinia Psidii ◽  
Plant Biosecurity

The use of sentinel or expatriate plants is a growing concept for risk assessment in plant biosecurity. This approach involves ascertaining the presence and impact of pests and pathogens on plants foreign to a given location but planted in international botanic gardens or arboreta. The data obtained provide information on the potential pest status of these pests and pathogens, as invasive alien species (IAS), to plant species in their native or indigenous range. Assessment of the biosecurity threat from IAS for indigenous plants not found within the geographic distribution of these pests and pathogens is challenging, however, as they may be relatively taxonomically distinct from plants found in the distribution of the IAS and can be in different climates and environments. We examine the sentinel/expatriate concept in relation to risk assessment for myrtle rust (Austropuccinia psidii) on New Zealand Myrtaceae on these plants found in botanic gardens and arboreta outside New Zealand. Between September 2017 and September 2018, we identified and then contacted 65 botanic gardens or arboreta that putatively had New Zealand Myrtaceae and were within the known distribution of myrtle rust. We asked for information on the presence of New Zealand Myrtaceae species in their collections and whether these plants were infected by myrtle rust. Sixteen gardens/arboreta responded; most were in Australia or the United States. Only one of these gardens provided information that was useful for biosecurity risk assessment for myrtle rust on New Zealand Myrtaceae. The results are discussed in the context of plant biosecurity risk assessment and the broader sentinel/expatriate plant concept.

scholarly journals Transcriptome Analysis of Eucalyptus grandis Implicates Brassinosteroid Signaling in Defense Against Myrtle Rust (Austropuccinia psidii)

2021 ◽  
Vol 4 ◽  
Author(s):  
Shae Swanepoel ◽  
Caryn N. Oates ◽  
Louise S. Shuey ◽  
Geoff S. Pegg ◽  
Sanushka Naidoo
Keyword(s):  
Disease Resistance ◽  
Rna Sequencing ◽  
Plant Disease Resistance ◽  
Rust Fungus ◽  
Eucalyptus Grandis ◽  
Post Inoculation ◽  
Puccinia Psidii ◽  
Myrtle Rust ◽  
Brassinosteroid Signaling ◽  
Austropuccinia Psidii

Eucalyptus grandis, in its native Australian range, varies in resistance to Austropuccinia psidii (syn. Puccinia psidii). The biotrophic rust fungus, A. psidii is the causal agent of myrtle rust and poses a serious threat to Australian biodiversity. The pathogen produces yellow pustules of urediniospores on young leaves and shoots, resulting in shoot tip dieback, stunted growth, and death. Dissecting the underlying mechanisms of resistance against this pathogen will contribute to improved breeding and control strategies to mitigate its devastating effects. The aim of this study was to determine the molecular dialogue between E. grandis and A. psidii, using an RNA-sequencing approach. Resistant and susceptible E. grandis seedlings grown from seed collected across its natural range were inoculated with the pandemic biotype of A. psidii. The leaf tissue was harvested at 12-h post inoculation (hpi), 1-day post inoculation (dpi), 2-dpi and 5-dpi and subjected to RNA-sequencing using Illumina 50 bp PE reads to a depth of 40 million reads per sample. Differential gene expression and gene ontology enrichment indicated that the resistant seedlings showed controlled, coordinated responses with a hypersensitive response, while the susceptible seedlings showed no systemic response against myrtle rust. Brassinosteroid signaling was apparent as an enriched term in the resistant interaction at 2-dpi, suggesting an important role of this phytohormone in defense against the pathogen. Brassinosteroid mediated signaling genes were also among the candidate genes within two major disease resistance loci (Puccinia psidii resistance), Ppr3 and Ppr5. While brassinosteroids have been tagged as positive regulators in other plant disease resistance interactions, this is the first report in the Eucalyptus – Austropuccinia psidii interaction. Furthermore, several putative resistance genes, underlying known resistance loci and implicated in the interaction have been identified and highlighted for future functional studies. This study provided further insights into the molecular interactions between E. grandis and A. psidii, contributing to our understanding of this pathosystem.

scholarly journals Transcriptional Responses of Escherichia coli K-12 and O157:H7 Associated with Lettuce Leaves

2012 ◽  
Vol 78 (6) ◽  
pp. 1752-1764 ◽  
Author(s):  
Ryan C. Fink ◽  
Elaine P. Black ◽  
Zhe Hou ◽  
Masayuki Sugawara ◽  
Michael J. Sadowsky ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Leaf Surface ◽  
Short Term ◽  
Transcriptional Responses ◽  
Content Type ◽  
E Coli ◽  
Leaf Surfaces ◽  
K 12

ABSTRACTAn increasing number of outbreaks of gastroenteritis recently caused byEscherichia coliO157:H7 have been linked to the consumption of leafy green vegetables. Although it is known thatE. colisurvives and grows in the phyllosphere of lettuce plants, the molecular mechanisms by which this bacterium associates with plants are largely unknown. The goal of this study was to identifyE. coligenes relevant to its interaction, survival, or attachment to lettuce leaf surfaces, comparingE. coliK-12, a model system, andE. coliO157:H7, a pathogen associated with a large number of outbreaks. Using microarrays, we found that upon interaction with intact leaves, 10.1% and 8.7% of the 3,798 shared genes were differentially expressed in K-12 and O157:H7, respectively, whereas 3.1% changed transcript levels in both. The largest group of genes downregulated consisted of those involved in energy metabolism, includingtnaA(33-fold change), encoding a tryptophanase that converts tryptophan into indole. Genes involved in biofilm modulation (bhsAandybiM) and curli production (csgAandcsgB) were significantly upregulated inE. coliK-12 and O157:H7. BothcsgAandbhsA(ycfR) mutants were impaired in the long-term colonization of the leaf surface, but onlycsgAmutants had diminished ability in short-term attachment experiments. Our data suggested that the interaction ofE. coliK-12 and O157:H7 with undamaged lettuce leaves likely is initiated via attachment to the leaf surface using curli fibers, a downward shift in their metabolism, and the suppression of biofilm formation.

How an Indigenous community responded to the incursion and spread of myrtle rust (Austropuccinia psidii) that threatens culturally significant plant species – a case study from New Zealand

2019 ◽  
Vol 25 (4) ◽  
pp. 348 ◽  
Author(s):  
Amanda Black ◽  
Melanie Mark-Shadbolt ◽  
Gary Garner ◽  
Jenny Green ◽  
Tame Malcolm ◽  
...  
Keyword(s):  
Social Media ◽  
New Zealand ◽  
Indigenous Community ◽  
Rust Disease ◽  
Pests And Diseases ◽  
Historical Significance ◽  
Myrtle Rust ◽  
Plant Nursery ◽  
Austropuccinia Psidii

The incursion of the myrtle rust disease (Austropuccinia psidii) was officially confirmed on 3 May 2017 at a plant nursery located in Kerikeri, North Island, New Zealand. Since then the presence of myrtle rust has now been located throughout New Zealand, with additional outbreaks in Taranaki, Waikato and Bay of Plenty. It has been detected on a range of Myrtaceaea species including ramarama (Lophomyrtus bullata), pōhutukawa (Metrosideros excelsa), Monkey apple (Syzygium smithii), mānuka (Leptospermum scoparium), and Eucalyptus spp. (E. botryoides). Many of these species are iconic to the Indigenous Māori and have historical significance, being taonga (treasures). Since the incursions, Te Tira Whakamātaki (National Māori Biosecurity Network), have been informing Māori communities throughout New Zealand about the potential impacts of myrtle rust via a series of regional meetings (hui), email and social media that have included brief reports and recommendations. Feedback from these meetings and social media has strongly highlighted the desires of Māori communities to be active participants in decision-making and response plans for the management of myrtle rust as well as other pests and diseases. In this paper, we describe the journey of an Indigenous community approach to a modern biosecurity incursion.

scholarly journals Monitoring Austropuccinia psidii (myrtle rust) on New Zealand Myrtaceae in native forest

2020 ◽  
Vol 44 (2) ◽  
Author(s):  
Roanne Sutherland ◽  
◽  
Julia Soewarto ◽  
Rob Beresford ◽  
Beccy Ganley
Keyword(s):  
New Zealand ◽  
Native Forest ◽  
Myrtle Rust ◽  
Austropuccinia Psidii

scholarly journals Compiling myrtle rust surveillance data for the 2017-18 New Zealand incursion

2018 ◽  
Vol 71 ◽  
pp. 356
Author(s):  
Rebecca E. Campbell ◽  
David A.J. Teulon
Keyword(s):  
New Zealand ◽  
Visual Information ◽  
Surveillance Data ◽  
Monitoring Data ◽  
Easy Access ◽  
Sampling Effort ◽  
Multiple Sources ◽  
Myrtle Rust ◽  
Food Research ◽  
Austropuccinia Psidii

As the observed distribution of myrtle rust (Austropuccinia psidii) changes within New Zealand, many stakeholders are interested in the spread of this disease, resulting in a number of organisations carrying out various levels of monitoring. There is a need to compile these monitoring data from multiple sources and provide easy access to basic disease distribution information, for the benefit of all interested parties. This should include not only locations of positive myrtle-rust detections, but also the rate of monitoring in areas where it has not yet been detected (confirmed absence). This project provided visual information in the form of maps that are easy to interpret by general and/or specific users. Resolution was useful and informative while maintaining privacy of landowners. A series of maps is presented, showing the advance in sampling effort and the disease distribution across New Zealand, as measured from surveillance effort from Ministry for Primary Industries, Department of Conservation, botanical gardens, Plant and Food Research and the Myrtle Rust Reporter app (NatureWatch NZ). Further analysis of such data will inform ongoing management and research.

Drepanopeziza ribis. [Descriptions of Fungi and Bacteria].

1979 ◽  
Author(s):  
C. Booth
Keyword(s):  
New Zealand ◽  
Geographical Distribution ◽  
Leaf Spot ◽  
Leaf Surface ◽  
Leaf Surfaces ◽  
Water Borne

Abstract A description is provided for Drepanopeziza ribis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Ribes spp. DISEASE: Causes leaf spot or anthracnose of currants and gooseberries. Symptoms consist of small, dark brown, round or irregular spots scattered over the leaf surface. They may coalesce if numerous. Infected leaves may turn yellow (especially in gooseberry) and fall. Minute greyish acervuli develop in lesions on upper and lower leaf surfaces. Lesions may also occur on petioles and peduncles, where they are elongated, and on fruit. GEOGRAPHICAL DISTRIBUTION: Europe, N. America, Japan, Australia and New Zealand (CMI Map 187, ed. 2, 1967). TRANSMISSION: By water-borne conidia produced from the Gloeosporidiella state on leaf lesions. Apothecia are produced from saprophytic growth on fallen diseased leaves and they produce air-borne ascospores in spring.

scholarly journals Efficacy of Fungicides Applied for Protectant and Curative Activity Against Myrtle Rust

Plant Disease ◽  
2020 ◽  
Vol 104 (8) ◽  
pp. 2123-2129
Author(s):  
Amin K. Pathan ◽  
William Cuddy ◽  
Mark O. Kimberly ◽  
Kwasi Adusei-Fosu ◽  
Carol A. Rolando ◽  
...  
Keyword(s):  
New Zealand ◽  
Host Plants ◽  
Water Control ◽  
Effective Protection ◽  
Fungicide Application ◽  
Myrtle Rust ◽  
Interaction Terms ◽  
Austropuccinia Psidii ◽  
Optimum Application ◽  
Demethylation Inhibitor

Myrtle rust, caused by the pathogen Austropuccinia psidii, affects species of the Myrtaceae, many of which are endemic to Australia and New Zealand. Originating from South America, A. psidii is now present in both countries, necessitating effective chemical control for disease management. Using an artificial inoculation protocol, the efficacy of eight fungicides (tebuconazole/trifloxystrobin, cyproconazole/azoxystrobin, fosetyl aluminum, triforine, triadimenol, oxycarboxin, copper, and tebuconazole) applied as curative or protectant treatments was tested on two native New Zealand species (Lophomyrtus × ralphii and Metrosideros excelsa). The impacts of rate (×2), frequency (single or double), and timing (pre- or postinfection) of fungicide application were investigated. Overall, the most effective fungicides tested across both species were those that included a demethylation inhibitor and strobilurin mix, notably tebuconazole/trifloxystrobin (Scorpio) and cyproconazole/azoxystrobin (Amistar Xtra). These fungicides significantly reduced infection of host plants relative to the water control. Timing of application significantly affected bioefficacy, with applications made 7 days before inoculation or 7 days after inoculation being generally the most effective. The rate of fungicide application was not significant for both host species, with few interaction terms showing overall significance. Key findings from this study will set the foundation for further fungicide bioefficacy research conducted to evaluate formulations and adjuvant mixtures, determine suitable application methods for enhanced retention and coverage, and derive optimum application time for effective protection of native and exotic Myrtaceae species in New Zealand.

The pandemic strain of Austropuccinia psidii causes myrtle rust in New Zealand and Singapore

2019 ◽  
Vol 48 (3) ◽  
pp. 253-256 ◽  
Author(s):  
E. du Plessis ◽  
G. M. Granados ◽  
I. Barnes ◽  
W. H. Ho ◽  
B. J. R. Alexander ◽  
...  
Keyword(s):  
New Zealand ◽  
Pandemic Strain ◽  
Myrtle Rust ◽  
Austropuccinia Psidii

scholarly journals Predicting the climatic risk of myrtle rust during its first year in New Zealand

2018 ◽  
Vol 71 ◽  
pp. 332-347 ◽  
Author(s):  
Robert M. Beresford ◽  
Richard Turner ◽  
Andrew Tait ◽  
Vijay Paul ◽  
Gregor Macara ◽  
...  
Keyword(s):  
New Zealand ◽  
Process Model ◽  
Weather Conditions ◽  
Coastal Areas ◽  
First Year ◽  
The South ◽  
Myrtle Rust ◽  
The North ◽  
Weather Model ◽  
Austropuccinia Psidii

After the first detection of myrtle rust (Austropuccinia psidii) on mainland New Zealand in May 2017, the Ministry for Primary Industries sought information about how weather conditions would affect regional and seasonal risk of disease establishment to help plan the incursion response. Using internationally published information, a pathogen-process model was developed to predict infection, latent period and sporulation in relation to weather variables (temperature, relative humidity and solar radiation). This Myrtle Rust Process Model (MRPM) was implemented by the National Institute of Water and Atmospheric Research Limited using numerical weather model data to produce weekly maps of potential risk. Predicted risk was greatest in northern North Island and decreased further south, but was still substantial in coastal areas of the north-western South Island during summer and autumn. Risk was low in southern coastal areas of the South Island and the lowest risk occurred in mountainous areas, particularly in the South Island. Retrospective analysis of surveillance data showed that the MRPM accurately predicted geographic risk and it is currently in use for tactical planning of incursion surveillance and organism management.  

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