Oral Abstracts Monday 20 November: Pre-Conference Workshops Workshop 1: Breaking Ground in Australian Nematology Workshop 2: Grapevine Virology 101 Workshop 3: New approaches for surveillance and monitoring of plant pathogens Tuesday 21 November: Conference Day One: PRESIDENTIAL ADDRESS: Dr Andrew Geering, President of the Australasian Plant Pathology Society KEYNOTE ADDRESS 1: Prof Jon West, Rothamsted Research SESSION 1 A: New Technologies (Artificial intelligent (AI)) and Novel Methods in Plant Pathology and Disease Control SESSION 1 B: Host Resistance Breeding and Pathogenomics SESSION 1 C: Diagnostics, Biosecurity SESSION 1 D: Integrated Disease Management/Biological Control SESSION 2 A: Molecular Plant Disease Interactions SESSION 2 B: Microbiomes and Disease Complex SESSION 2 C: Plant Disease Management, Chemical Resistance SESSION 2 D: Integrated Disease Management/Biological Control KEYNOTE ADDRESS 2: Dr Peter Dodds, CSIRO KEYNOTE ADDRESS 3: Prof Linda Kinkel, The University of Minnesota Wednesday 22 November: Conference Day Two: DANIEL MCALPINE LECTURE: Dr Jenny Davidson KEYNOTE ADDRESS 4: Dr Murray Sharman, Queensland Department of Agriculture and Fisheries SESSION 3 A: Diagnostics, Biosecurity and Community/Industry Engagement/Extension SESSION 3 B: Epidemiology, Ecology, Modelling and Risk Analysis SESSION 3 C: New Diseases and Climate Change SESSION 3 D: Taxonomy, Diversity and Evolution SESSION 4 A: New Technologies (Artificial intelligent (AI)) and Novel Methods in Plant Pathology and Disease Control and Forest and Perennial Crop Diseases SESSION 4 B: Epidemiology, Ecology, Modelling and Risk Analysis SESSION 4 C: Diagnostics, Biosecurity SESSION 4 D: Plant Disease Management, Chemical Resistance KEYNOTE ADDRESS 5: Dr Florent Trouillas, University of California Thursday 23 November: Conference Day Three: KEYNOTE ADDRESS 6: Dr Walter F Mahaffee, United State Department of Agriculture – Agricultural Research Service KEYNOTE ADDRESS 7: Prof Lindsey du Toit, Washington State University SESSION 5 A: New Technologies (Artificial intelligent (AI)) and Novel Methods in Plant Pathology and Disease Control SESSION 5 B: Epidemiology, Ecology, Modelling and Risk Analysis SESSION 5 C: Diagnostics, Biosecurity SESSION 5 D: Integrated Disease Management/Biological Control SESSION 6 A: Integrated Disease Management/Biological Control SESSION 6 B: Microbiomes and Disease Complex and other SESSION 6 C: Diagnostics, Biosecurity SESSION 6 D: Plant Disease Management, Chemical Resistance KEYNOTE ADDRESS 8: Dr Louise Shuey, Department of Agriculture and Fisheries Contents (continued) Friday 24 November: Post-Conference Workshops Workshop 5: Xylella Poster Abstracts P1 - P9: Diagnostics, Biosecurity P10 – P11: Epidemiology, Ecology, Modelling and Risk Analysis P12 – P14: Forest and Perennial Crop Diseases P15 – P17: Host Resistance Breeding P18 – P22: Integrated Disease Management/Biological Control P23: Microbiomes and Disease Complex P24 - P28: Molecular Plant Disease Interactions P29: New Diseases and Climate Change P30 – P31: New Technologies (Artificial intelligent (AI)) and Novel Methods in Plant Pathology and Disease Control P32 -P42: Plant Disease Management, Chemical Resistance P43 -P47: Taxonomy, Diversity and Evolution Contents (continued) Disclaimer Responsibility for the contents of papers included in these Proceedings resides with the authors. Copyright © 2023 Copyright resides with the authors´ and/or their employing or funding institutions. Other than brief abstracts, no part of this publication may be produced in any form without the consent of the authors. Presenters: Dr Mike Hodda - CSIRO, Canberra ACT; Dr Katherine Linsell - SARDI, Urrbrae SA; Dr Sarah Collins - DPIRD, Perth WA; Dr Rebecca Zwart - University of Southern QLD, Toowoomba QLD; Plus Guest Presenters Summary A workshop on what’s breaking in nematology. We have new species to discuss (in the turf world) known species that are not what we thought (like cereal cyst nematode), new species that we definitely didn’t want (Root knot nematode findings in our north) and new information on species that cause huge economic losses annually in Australian agriculture. We also have techniques for nematode extraction, inoculum in glasshouse trials and in the molecular world. Hear from those closest to these changes, discuss what they might mean, and have a look at the nematodes in question. Then finish by engaging with a panel of nematologists on where nematology is going and should concentrate in the years ahead. With panellists ranging from the recently converted to very experienced, and questions from the floor, we hope this will be a lively session to end the day! The workshop is a series of talks by people working on most of the most damaging nematode genera, including Cyst Nematodes (genus Heterodera), Root-Knot Nematodes (genus Meloidogyne), Root-Lesion Nematodes (genus Pratylenchus), and turf nematodes (several genera). There will be demonstrations of each of these under the microscope where possible. After lunch, there is a series of talks on molecular methods in nematology, from routine identifications to detailed taxonomic examinations of the identity and validity of species and how these can be incorporated into diagnostic tests. Other talks in this section will discuss what can be learned from studying whole genomes and e-DNA. The final part of the workshop is a discussion of what all this might mean for nematology with a diverse panel of nematologists and questions and comments from the floor. 1. Cyst Nematodes: Dan Huston (CSIRO), Sarah Dunstan (CSIRO) 2. Root-Knot Nematodes: Wayne O’Neill & Dylan Corner (QDAF) & Guest presenter (NT DITT) 3. Root-Lesion Nematodes: Sarah Collins (WA DPIRD), Mike Hodda (CSIRO) 4. Turf Nematodes: Peter Ruscoe (Turf consultant). 5. Techniques: Neil Wilson (Netagen), Dan Huston (CSIRO), Akshita Jain (DJPR-Vic/Latrobe Uni), Daniele Giblot-Ducray (SARDI), Mike Hodda (CSIRO) 6. Nematology past, present and future: Join the discussion with a diverse panel of nematologists on what developments such as those described might mean for nematode priorities, research, diagnostics, management, resistance breeding and other aspects of nematology. Having heard about new species, ups and downs in what we know about existing species and new techniques. Your questions from the floor welcomed. To answer these questions and others we have: Ian Riley (Consultant), Dan Huston (CSIRO), Ian Riley (University of Adelaide), Kerrie Davies (University of Adelaide). Workshop 1: Breaking Ground in Australian Nematology Presenters: Dr Monica Kehoe - DPIRD, South Perth WA; Dr Fiona Constable - AgVic, Bundoora, VIC Summary During this workshop we will cover the basics of Grapevine Virology in Australia. We will cover: • Information on the viruses themselves, what we know about them in the Australian context. Monica Kehoe, Kamalpreet Kaur and Dr Fiona Constable o Updates on recent research including: ▪ The prevalence and diversity of grapevine Pinot gris virus in Australia. Kamalpreet Kaur ▪ Molecular Epidemiology of Shiraz Disease with an Emphasis on Grapevine Virus A. Dr. Qi Wu (recorded) ▪ A snapshot of vineyard health in Victoria. Dr. Cliff Kinoti ▪ New technologies for virus detection. Dr. Monica Kehoe ▪ An update on the status of grapevine red blotch virus in Australia. Dr. Fiona Constable, Dr Monica Kehoe, Kamalpreet Kaur ▪ Establishing the National Grapevine Collection. Nick Dry ▪ Vine improvement: A national network. Chris Bennett • An introduction to the Sampling Protocol for Virus Diagnostics, including how to sample/submit to diagnostic services • An introduction to the Australian Grapevine Virology Technical Committee • Discussion on the latest diagnostic test development, and future directions . Fiona Constable, Robin MacDiarmid, Sharon Harvey, Cath Kidman, Nick Dry and Chris Bennett Workshop 2: Grapevine Virology 101 Presenters: Dr Rohan Kimber - Crop Sciences, SARDI SA; Prof Jon West, Protecting Crops and the Environment Group, Rothamsted Research, United Kingdom; Plus Guest Presentations/Demonstrations from Dr Walt Mahaffee, Dr Ismail Ismail, Dr Mohsen Khani, Dr Andrew Baker, Lewis Collins, and Dr Michelle Demers Summary This workshop will demonstrate and discuss common and innovative spore trapping systems for the surveillance of airborne plant pathogens related to plant health. It will be held at SARDI’s Plant Health Surveillance laboratory in the Plant Research Centre located at the Waite Research Institute. Researchers with interests in spore trapping, digital & mechatronic technologies, diagnostic techniques and data visualisation to end-users are encouraged to attend. The agenda will comprise of presentations, hands-on demonstrations and discussion sessions with the aim to facilitate a collaborative and interactive forum to overview emerging technologies and platforms, advantages and disadvantages, and present opportunities these offer aerobiological research and the surveillance of airborne plant pathogens. This includes drawing on the expertise of Professor Jon West (Rothamsted Research), who is internationally recognised in his research on aerobiology, and will co-chair this workshop. Workshop 3: New approaches for surveillance and monitoring of plant pathogens 167 Pioneering discoveries in plant virology from Australia (what lessons can we learn from history?) Geering A1 1The University of Queensland, St Lucia, Australia Plant pathology in Australia prior to World War II was full of challenges. According to Walter Carne, there was “an absence of colleagues of similar interests with whom to consult, …defects of libraries and equipment, …ignorance of the work going on with other States and the feeling of geographical and mental isolation”. Despite these challenges, truly world class research emerged from Australia, and the Waite Institute in Adelaide was a centre of excellence in plant pathology. In this talk I will follow the story of the discovery of tomato spotted wilt virus, which provides a microcosm of the beginnings of State and Federal collaboration in agricultural research. Research on this virus got off to a rocky start, with personality clashes between individuals but eventually great progress was made in understanding the aetiology and epidemiology of this virus. Two of the main protagonists in the tomato spotted wilt virus story, Geoffrey Samuel and Jack Bald, were eventually lured to the mother country, England, by promises of greater research opportunities, leaving behind Rupert Best as the lone virologist at the Waite Institute. Best turned his attention to biochemical characterisation of tobacco mosaic virus and was among the first to demonstrate that it was composed of protein and nucleic acid. It has been suggested by some that he should have been Australia’s first Nobel Prize winner, but instead the award went to a well-connected American, Wendell Stanley. At the conclusion of my talk, I will review what lessons can be learnt from this period of research. The adage that history repeats itself is still pertinent. PRESIDENTIAL ADDRESS 204 Emerging technologies for surveillance and monitoring of sporadic pathogens Professor Jon West1 1 Rothamsted Research Authors: Jonathan S. West, Gail G.M. Canning & Kevin M. King Surveillance and monitoring of pathogens optimises applications of crop protection products and is particularly useful for sporadic pathogens that are difficult to forecast. Established and emerging technologies, include imaging from satellites, aircraft or in-field sensors, visual observations, portable diagnostic tests, weather-based models and airborne inoculum detection. Optical sensing by spectroscopy or imaging from satellites or aircraft can cover a wide land area but often cannot differentiate between different crop stress and detection may be too late to enable control. The most promising optical sensing approach for early detection appears to be from proximal sensors using fluorescence or image analysis to identify anomalies but often needs controlled conditions. Portable diagnostic assays are increasingly available as Lateral Flow Devices or LAMP assay kits and can be used to confirm identity of symptoms or even to detect incubating infections that would otherwise be missed by a simple visual inspection. These kits can also be used with samples from spore traps and for some diseases initiated by airborne spores, this approach is now being automated to detect pathogen inoculum before infection occurs. Alternatively, airborne spores can be detected based on optical properties of the spores themselves. Integration of wireless reporting improves the timeliness of results from automated devices compared to samples being sent to a lab. This gives more time for application of crop protectant products and is essential for rapidly developing diseases such as potato blight. Current research is combining automated spore traps with metagenomic sequence-based technologies (e.g. minION sequencing) to enable rapid monitoring of the entire aerobiome to profile abundance of multiple pathogens and even genetic traits such as fungicide resistance. The area represented by a single spore trap, depends on atmospheric conditions and the spore trap’s height above ground but can serve as a proxy for relatively large areas. Keynote Address 1 192 Understanding pathogen populations using qPCR analyses of airborne spore samples to assist in the management of Eutypa dieback of grapevines Kimber R1, Hill K1, Giblot-Ducray D1, Sosnowski M1, Oswald E2, Baker A3, Johnson S4 1SARDI, Urrbrae, Australia, 2Treasury Wine Estates Wynns Coonawarra, Coonawarra, Australia, 3Data Effects, Adelaide, Australia, 4AUSVEG, Melbourne, Australia An iMapPESTS Sentinel (www.imappests.com.au) with a cyclone spore sampler (200 l/min) was deployed at Treasury Wine Estates Wynns Coonawarra (SA) site in 2022 adjacent a Burkard spore trap (10 l/min) traditionally utilised in plant pathology. Quantification of airborne pathogens was examined using qPCR. Key pathogens within Eutypa dieback, including Cryptovalsa ampelina, Eutypa lata, and other Eutypella and Cryptovalsa species were targeted using 3 different assays. Additionally, a generic assay (modified A), was applied to target a range of species in the Xylariales order, which include the Eutypa dieback species complex (multiple genera). Erysiphe necator and Botrytis cinerea were also analysed fortnightly within traceable samples in the iMapPESTS diagnostics pipeline then compared to traditional trapping at the end of season. Results showed Cryptovalsa ampelina was the dominant pathogen in the Eutypa dieback complex. This contrasts with findings in other regions where Eutypa lata often drives this complex. Additionally, the Sentinel (2 m) detected early spore dispersal events not captured by the Burkard sampler at a lower height (50 cm), which would align with pruning activities, a vulnerable period of vines to infection by Eutypa dieback pathogens. Monitoring also revealed mass dispersal of foliar pathogens E. necator and B. cinerea mechanically liberated into the air by barrel pruning activities. These insights into pathogen population shifts offer new opportunities for airborne pathogen surveillance or monitoring dynamics for improved management of fungal diseases. DNA- based diagnostics is further amenable to additional analytics of air samples, such as fungicide resistance or pathogen virulence profiles, now being investigated at SARDI. Connected digital outputs using the iMapPESTS surveillance pipeline has provided device-to- data delivery to researchers and industry end-users. This could offer devices deployed into risk pathways or area freedom points for trade protection for Australian imports and exports and showcases innovative and sustainable solutions to Australia’s biosecurity programs. Session 1 A: New Technologies (Artificial intelligent (AI)) and Novel Methods in Plant Pathology and Disease Control 179 Next-generation spore trapping: exploring opportunities and overcoming challenges Demers M1,2, Collins L1 1Bioscout Pty Ltd, Marrickville, Australia, 2School of Life and Environmental Sciences, The University of Sydney, Camperdown, Australia Fungal diseases pose a significant threat to agricultural productivity and food security worldwide. To help mitigate these challenges, early detection of pathogens is crucial for effective disease management. Traditional pathogen detection relies on manual sampling methods, which are labour-intensive and frequently fail to provide timely data, preventing early disease intervention in commercial farming operations. However, recent technological advancements offer promising opportunities for overcoming these challenges. This talk aims to overview the opportunities and challenges associated with automated fungal spore trapping for agriculture. First, an explanation will be provided as to how technologies, including artificial intelligence, machine learning, and automated microscopy, have improved how we can detect airborne fungal crop diseases and case studies on how this technology has been implemented to date. It will explore the possibilities posed by providing aerobiological and environmental data in near real-time on a localised and large geographic scale. This includes providing early warning systems for farmers to implement targeted interventions and tracking large-scale disease spread in near real-time. It will also explore several challenges that must be addressed to facilitate the successful implementation of automated fungal spore trapping. These challenges include dealing with diverse environmental conditions, evaluating the accuracy of machine-learning models, working within limits posed by detection resolution, and assessing the effects of this data on pest management in-field. By fostering knowledge exchange and interdisciplinary collaboration, we can harness the power of automation to improve disease monitoring and management strategies, paving the way for a more sustainable and resilient agricultural future in a rapidly changing world. 189 Integrated digital biosecurity systems for plant health diagnostics Hill M1, Arnold J1, Grgurinovic C1, Tran-Nguyen L1 1Plant Health Australia, Deakin, Australia Plant Health Australia (PHA) administers a range of digital systems that are integral to national plant biosecurity, including the Pest and Disease Image Library (PaDIL), the Australian Plant Pest Database (APPD) and AUSPestCheck®. APPD and PaDIL are of strategic importance to Australia's national biosecurity system in supporting the accurate diagnosis of plant pests and diseases for regulatory and management purposes, and determination of pest status. AUSPestCheck® is the repository for national surveillance data and supports critical data from the National Plant Health Surveillance Program and from industry partners. Each of these digital systems facilitate sharing of biosecurity information and data necessary for efficient functioning of our national biosecurity system. While these applications are aligned in purpose, there is an opportunity to think holistically across the services provided by PHA and look at ways to bring their functions and features together as integrated digital biosecurity systems. Plant Health Australia have also led the scoping required for “National coordination of high throughput sequencing data for a connected diagnostics system”. The vast amount of data being generated by HTS technology has created a need for a secure, centralised storage database supporting the submission, sharing and analysis of plant pest genomic data. Links to the APPD and PaDIL are clear, as there is such value of having specimens linked to a reference collection of sequence data. In this talk we will cover what each of the Digital Systems administered by PHA currently do, future enhancements, areas where they could be further aligned, and the scope for new digital systems and services to be developed and integrated into these current systems. 90 Harnessing mobile, foliar applied double-stranded RNA for effective RNAi against plant pathogens Brosnan C1, Fletcher S1, Sawyer A1, Gardiner D1, de Felippes F2, Carroll B1, Waterhouse P2, Mitter N1 1University of Queensland, Brisbane, Australia, 2Queensland University of Technology, Brisbane, Australia Foliar application of double-stranded RNA (dsRNA) as RNA interference(RNAi)-based biopesticides represents a sustainable alternative to traditional transgenic, breeding or chemical-based crop protection strategies. A key feature of RNAi in plants is its ability to act non-cell autonomously, a process that plays a critical role in plant development and protection against pathogens. However, whether RNAi induced by foliar dsRNA application can act non-cell autonomously remains debated and the potential mechanisms and implications of this movement largely unexplored. Here we show that upon foliar application, unprocessed full-length dsRNA enters the leaf vasculature and rapidly moves to vegetative, reproductive and below ground tissue types in several model plant and crop hosts. Intact unprocessed dsRNA was detected in the apoplast of distal tissue types and maintained in subsequent new growth indicating apoplastic rather than symplastic transport. Furthermore, we show that mobile dsRNA is functional against root-infecting fungi and foliar viral pathogens. When used to target fungal pathogens, mobile dsRNA transfers to the fungus where it is processed by the fungal RNAi machinery to elicit gene silencing. Using a novel biochemical purification technique and small RNA sequencing we have for the first time diagnosed function siRNA species derived from foliar applied dsRNA in both in the applied and distal infected tissue types. Our mechanistic dissection of the uptake and maintained movement of intact, functional dsRNA provides crucial insights into RNAi biopesticides and stands to add significant benefit to this emerging field of plant protection. 193 Optimisation of BioClay™ formulation and application to control botrytis grey mould of lentil Khani M1,2, Krysinska-Kaczmarek M1, Blake S1,2, Harbottle S3 1South Australian Research and Development Institute (SARDI), Adelaide, Australia, 2School of Agriculture, Food and Wine, University of Adelaide, Adelaide, Australia, 3Nufarm, Melbourne, Australia BioClay™ is a new bio-pesticide containing layered double hydroxide (LDH) microclay sheets that carry double stranded RNA (dsRNA). Using spray-induced gene silencing technology, a specific dsRNA construct incorporated in BioClay™ is applied on plants and targets pathogen growth or virulence gene/s that eventually reduces plant disease. We developed a reliable and high throughput protocol for screening BioClay™ products to control botrytis grey mould (BGM) on lentil plants. Briefly, BioClay™, or its components dsRNA and LDH, plus a penetrant were applied on plants to examine the efficacy of these products on BGM in a controlled environment room equipped with LED light. Plants inoculated with Botrytis cinerea received humidity after inoculation, and BGM progression was assessed on several days after inoculation (DAI), up to 21DAI. Early developed products such as raw and washed LDH, and BioClay™ caused phytotoxicity. Along with improvements to product formulation, we screened several penetrants at different rates on 2–6-week-old plants. The phytotoxicity issue was resolved using a safe rate of some penetrants such as Pulse® at 0.005% v/v, on 4- week-old plants. The best control of BGM was achieved when dsRNA was applied 5DAI, compared to a few days before inoculation (5-2DBI) or even 0-3DAI. The concentration of dsRNA DCL1/2 in BioClay™ was progressively reduced from higher rates (0.1-0.6 mg/ml) used in initial trials and optimised to 0.05 mg/ml. Several dsRNA constructs targeting different genes, clay formulations and loading ratios of dsRNA/clay were examined and eventually achieved 80% efficacy control of BGM on lentil. Employing BioClay™ is a promising option for control of BGM, and future work will focus on further optimisation of the protocol and products. 100 Factors contributing to the expression of blackleg disease (Leptosphaeria maculans) of canola in the context of breeding for quantitative disease resistance Sprague S1, Marcroft S2, Van de Wouw A3, Barrett L1 1CSIRO, Canberra, Australia, 2Marcroft Grains Pathology, Horsham, Australia, 3University of Melbourne, Parkville, Australia Blackleg disease is a serious economic constraint to canola production globally. Host resistance to yield-limiting crown canker symptoms is either qualitative or quantitative. Qualitative resistance can be rapidly overcome due to the high mutability of Leptosphaeria maculans and therefore, quantitative resistance (QR) is considered a more durable form of resistance. The aim was to identify factors influencing blackleg expression to improve phenotypic characterisation of canola for application to breeding. Experiments were conducted by inoculating (i) with a genetically uniform single isolate in a controlled environment (ii) with a genetically diverse blackleg population under field-like conditions and (iii) with the same set of three blackleg populations in three different field environments. Differences in disease severity were detected between cultivars at various plant growth stages. A significant isolate x host genotype interaction was consistently measured in multiple experiments inoculated with either single isolates or diverse blackleg populations. There was a significant effect of environment on blackleg severity when host and pathogen were held constant. Our findings highlight the complex interplay between host, pathogen and environment in the expression of blackleg disease in canola with implications for both characterisation of quantitative resistance and disease management. In a breeding context, screening with single isolates may be useful to detect individual QTL associated with QR but these may not contribute to QR when screened against a population. Strong QR is likely a combination of genes with additive effects requiring further breeding and characterisation to identify optimal combinations. The effect of environment should be a focus for future research with significant implications for phenotyping for breeding and identifying scenarios which lead to severe disease and yield reductions. Session 1 B: Host Resistance Breeding and Pathogenomics 32 Exploring the wilds for resistance to banana bunchy top virus Dela Cueva F1, Perez N1, Yanos L1, Gueco L1, Thomas J 2 1University Of The Philippines Los Baños-Institute Of Plant Breeding, College Of Agriculture and Food Science, Los Baños, Philippines, 2 Queensland Alliance for Agriculture and Food Innovation, University of Queensland, Brisbane, Australia Edible bananas (Musa sp.) contain genome components of the wild, seeded progenitor M. acuminata (AA) and often also M. balbisiana (BB). Cultivars with a B genome component are often noted to be less susceptible to infection by banana bunchy top virus (BBTV). In the Philippines, the cv Lakatan (AAA) is very susceptible to BBTV while the cv Saba (BBB/ABB) may escape field infection for years. In this study, two wild progenitors of bananas were evaluated for disease response against BBTV. Two accessions of M. acuminata ssp. errans (AAW) and 34 of M. balbisiana (BBW) from the National Plant Genetic Resources Laboratory, IPB-UPLB germplasm collection were artificially inoculated with BBTV in a screenhouse using viruliferous aphids. Symptoms were monitored and plants indexed by PCR 3 and 6 months after inoculation. All M. acuminata ssp. errans plants and all ‘Lakatan’ controls were infected, whereas all plants of all M. balbisiana plants (BBW) remained uninfected. M. balbisiana plants subsequently transferred to a field under high BBTV inoculum pressure remained uninfected for more than five years, while all Lakatan control plants were infected after six months. To our knowledge, this is the first report of apparent immunity to BBTV and these wild M. balbisiana accessions will be further studied to uncover novel sources of BBTV resistance genes for functional genomics research, genome-wide association studies, and marker-assisted plant breeding applications. 108 Mining fungal pan-genomes for effector and fungicide resistance profiling for disease diagnosis and surveillance Hossain M1, Jones D1, Williams A1, Phan H1, Hane J1 1Centre for Crop and Disease Management, Curtin University, Perth, Australia Fungal crop diseases are mediated by pathogen-secreted effectors, the accurate identification of which can enable long-term crop disease resistance. In this study, we apply recently improved methods for predicting novel effector candidate profiles from pan- genome data. By combining this with cultivar-specific disease phenotyping and locations, we aim to develop a novel genome-based disease diagnostic and surveillance database/toolkit for efficient surveillance of known effectors and improved discovery of novel effectors. We also incorporate our recently developed fungicide-resistance (FR) allele search tool (FRAST) to assess the fungicide-resistance allele diversity and emergence risks across fungal populations. This study examines 648 Parastagonospora nodorum isolates, focusing on 260 local isolates from the Western Australian (WA) wheat-belt region, which are contrasted with 388 internationally sourced isolates. We observed profiles of relevant pathogenicity- indicators including: mating type, fungicide resistance alleles, and effector haplotypes/isoforms across evolving pathogen populations at a state level. Mating types show both MAT1-1 and MAT1-2 loci are dispersed across WA, indicating meiotic reproduction and subsequent genome diversification via repeat-induced point mutations (RIP). Combining pan-genomics with FRAST we detected multiple FR mutations across WA, consistent with reports of emerging resistance. We report RIP is a major driver of genome- wide mutations, yet the majority of retained RIP-like SNPs within predicted protein-coding genes were synonymous mutations. Effector isoform profiles were variable across WA, but phylogenetically consistent with localised sub-populations. For 5 currently known effector loci of P. nodorum, most isoform changes/diversity were due to a small number of RIP-like non-synonymous mutations. RIP apparently drives pathogenic adaptations at a whole- genome level but is typically held in check by selection against widespread deleterious non- synonymous mutations. We present this pan-genomic study as an effective diagnostic method to support crop disease management by enabling rapid identification of region- specific pathogen effector profiles and emerging fungicide resistance. 128 Whole genome approach to population genomics of Phytophthora cinnamomi in Australia Longmuir A1, Ziemann M1, Richardson M1, Cahill D1 1Deakin University, Waurn Ponds, Australia Since the first record of jarrah dieback disease in Western Australia in the 1920s, the causative agent, Phytophthora cinnamomi has continued to spread through south-western Australia, across much of Victoria and Tasmania and the east coast, devastating Australia’s ecosystems and native plant species in its wake. The oomycete’s distribution in Australia is well documented; however, knowledge of its genetic diversity within Australia is extremely limited. Given the pathogen’s wide host range of over 2000 Australian plant species and the variation between the ecosystems within which P. cinnamomi thrives, a robust understanding of its evolution and diversity within Australia, specifically with regard to genes involved in the infection process, will help us to understand why P. cinnamomi is such a successful pathogen. Here we present a large-scale population genomics analysis of 70 P. cinnamomi isolates collected across Australia. Utilising a whole-genome sequencing approach, we will quantify the genetic diversity of the species in Australia and identify genes undergoing selective pressure. We focus on drawing possible associations between genetic diversity, geographical location and host plant species. Understanding the genetic diversity and important genomic features of P. cinnamomi in Australia will bolster our understanding of what makes the species such a successful pathogen. Moreover, identifying key genes involved in infection may shed new light on potential novel strategies for disease control. 146 Utilisation of small RNA-omics and Rapid Genome Sequencing Complementary Strategy for characterisation of novel plant viruses Abeynayake S1, Gauthier M2, Lelwala R2,3, Hetherton A1, Fiorito S1, Elliott C3, Pattemore J3, Barrero R2, Dinsdale A1 1Plant Innovation Centre, Plant Import Operations, Biosecurity Plant and Science Services Division, Department of Agriculture, Fisheries and Forestry (DAFF), Mickleham, Australia, 2eResearch, Research Infrastructure, Academic Division, Queensland University of Technology, Brisbane, Australia, 3Operational Science and Surveillance, Science and Surveillance Group, Biosecurity Plant and Science Services Division, DAFF, , Plant viruses cause considerable economic loss in agricultural industries. Rapid and accurate identification of plant viruses and viroids is crucial for preventing disease outbreaks. Whilst small RNA-omics are transforming our capacity to detect plant viruses, the characterisation of novel viruses is still challenging due to the lack of whole genome coverage at low titre. Here, we report a small RNA sequencing (sRNA-Seq) followed by the Rapid Amplification of cDNA Overlapping Regions (RACOR) strategy for whole genome sequencing and characterisation of novel plant viruses. This approach resulted in the detection and characterisation of the complete genome sequence of a novel potexvirus, tentatively named “Adenium obesum potexvirus X” (AobPX) isolated from an Adenium obesum (desert Rose) plant held at the Post-Entry Quarantine (PEQ) facility (Mickleham, DAFF). Our results suggest that this method is suitable for rapid and complete genome sequencing of positive- single-strand RNA viruses with a poly A tail from infected plants showing a disease phenotype. This method can be further improved by using random hexamers to target viruses with or without poly A tails, enhancing our capacity to resolve complete viral genomes to facilitate biosecurity risk assessment and decision making. Session 1 C: Diagnostics, Biosecurity 161 Biosecurity engagement in horticulture in the Virginian growing region Todd C1,2, Hassan Z3, Sosnowski M1,2 1South Australian Research and Development Institute (SARDI), GPO Box 1671, Adelaide, Australia, 2University of Adelaide, PMB 1 Glen Osmond, Australia, 3AusVeg, 3 Glenarm Road Glen Iris, Australia AusVeg lead a series of grower education workshops under the “Peri-urban vegetable biosecurity pilot workshop” program in 2020-2022. Education workshops in South Australia focused on pests, diseases and growing in the northern Adelaide plains, particularly Virginia, in South Australia (SA). This area has intensive horticultural production, and growers from an abundance of nationalities, with a range in the size and complexity of operations, in this area. Consequently, significant language and cultural barriers have been found which may exacerbate the lack of engagement with biosecurity and testing for pests and diseases. These workshops were supported by diagnostic services to engage growers, inform BiosecuritySA of the pests in the area and were replicated in New South Wales and Victoria. Attendee survey results from SA supported the assumption of cultural diversity in the region, with growers and agronomists frequently indicating they spoke multiple languages. Workshops in the form of farm visits, with an introduction by a local consultant, were the most effective way that samples (38%) were collected during this project. Over the course of the project sixty-six diagnostic requests were made for 11 crop types, with capsicum (8), cucumber (12) and tomato (16) the most common. Reports were made of fungal (16), nematode (6), viral (5) and bacterial (5) pathogens, or the absence of pathogens (28), to individual growers. These reports combined with weekly surveillance data, provided by agronomists, were collated and circulated via a weekly report enabling understanding of pest and disease pressures in the region and management decisions into the future. A contribution to biosecurity surveillance was also made with the first identifications of: Verticillium isaacii, from tomato, and nematode Aphelenchoides fragariae, impacting parsnips. Cucumber Green Mottle Mosaic Virus (CGMMV) was also identified from one fruit sample; supporting the lack of area freedom claims for this virus in SA. 36 Exploring genomic insights into the whole genomes of Heterodera species Jain A1,2, Li T1, Kaur J1, Trollip C4, Huston D3, Hodda M3, Wainer J1, Mann R1, Edwards J1,2, Rodoni B1,2, Sawbridge T1,2 1Agriculture Victoria Research, Bundoora, Australia, 2School of Applied Systems Biology, La Trobe University , Bundoora, Australia, 3Australian National Insect Collection, National Research Collection Australia, Canberra, Australia, 4Department of Regional NSW, Sydney, Australia Cyst nematodes form a major taxon of plant-parasitic nematodes causing a significant economic impact globally. They are characterised by the female’s ability to retain hundreds of eggs in its body after the completion of its life cycle. They are notorious agricultural pests, classified into eight genera of which Heterodera and Globodera are two of the most economically important. Traditionally, detection of cyst nematodes is reliant upon morphological identification. However, this is time consuming and requires expertise, hence, there has been an increase in the use of molecular diagnostic strategies. Whole genome sequencing (WGS) provides information to identify unique molecular barcodes to distinguish species as well as underlying mechanisms of host invasion. However, WGS of cyst nematodes is difficult since it is very challenging to extract DNA from an individual juvenile. Therefore, millions of juveniles are pooled together to generate enough data to obtain a high-quality draft assemblies. To date, only six draft genomes have been sequenced which have given an insight into the diverse biological processes associated with cyst nematodes. Our study aims to sequence, assemble and annotate draft genomes of cyst nematodes belonging to the genus Heterodera including species native to Australia and couple of exotics. The goal of this genome sequencing effort is to expand on the existing genomic resources and provide usable data of sufficient quality to the nematology community and develop diagnostic assays for species identification and management. 98 Fusarium sp. [AF-18] - a friend and close confidant of polyphagous shot hole borer Pain N1, Wright D1, Croeser L1, Ireland K2, Cousins D1, Moir M1, Kehoe M1 1Department of Primary Industries and Regional Development, South Perth, Australia, 2Department of Biodiversity, Conservation and Attractions, Kensington, Australia The first Australian detection of Polyphagous shot hole borer (Euwallacea fornicatus, PSHB) occurred in Perth, Western Australia in August 2021. PSHB is a significant threat to amenity and horticulture trees globally. Upon detection, the Department of Primary Industries and Regional Development (DPIRD) established a biosecurity emergency incident response, with a quarantine area now incorporating 25 local government areas (871km²). PSHB has a wide host range (>500 plant species globally) and a symbiotic relationship with Ambrosia clade Fusarium species. This symbiotic relationship is a devastating combination; the beetle bores a ~1mm diameter hole into its host, creates galleries, and deposits Fusarium spores directly into the host plant’s vascular system as a food source for its larvae. The beetle galleries and the Fusarium growth disrupts the host’s vascular system, often causing limb and tree death. We optimised a fungal isolation method for beetle and host plant samples. The Fusariums isolated from PSHB samples were identified as Fusarium sp. [AF-18] by sequencing the ITS, TEF and RBP2 gene regions. Isolates are cultured, sequenced, morphologically described, and deposited into the Western Australian plant pathology Culture (WAC) collection. Other fungal cultures have also been isolated from beetle and wood samples that were submitted to DPIRD’s diagnostic laboratory services for further identification at a later date. Well defined workflows, rapid identification methods, and knowledge from incursions overseas enables the best outcome when responding to complex multi-species incursions such as PSHB and its associated Fusarium species. Ideally, ongoing knowledge-sharing of exotic species incursion responses between jurisdictions is required to promote early detection and maximise the likelihood of eradication of exotic species across Australia. 95 Xanthomonas euvesicatoria pv. euvesicatoria causes bacterial leaf spot of chili in Indonesia Utami D1,2, Jayasanti N2, Meale S1, Young A1 1The University Of Queensland, Gatton, Australia, 2Universitas Gadjah Mada, Sleman, Indonesia Chili (Capsicum sp.) is an important cash crop in the world with significant impacts in popular and traditional cultures. However, it has several serious diseases, including Bacterial Leaf Spot (BLS) which is caused by at least four Xanthomonas biotypes. The plant pathogen identification is crucial to provide proper management and avoid the spread of the disease. As the third biggest country producing chili, there is no information on the BLS pathogen in Indonesia. Chili samples exhibiting BLS symptoms were collected from 14 provinces in Indonesia. Symptomatic leaves were first screened with the ooze test, then isolations were made, and the resulting strains where initially characterised through amylase activity prior to sequence confirmation via the specific hypothetical protein and gyrase B loci. The bacterial pathogens were isolated and validated by Koch Postulates. One isolate was obtained, amylase test was conducted to differentiate X. euvesicatoria pv. euvesicatoria from X. vesicatoria and X. euvesicatoria pv. perforans. A pathogenicity test was conducted in two chili pepper cultivars which popular in Indonesia, C. frutescens var. trisula hijau and C. annuum var. annuum. The pathogenic bacteria were identified as Xanthomonas euvesicatoria pv. euvesicatoria based on the biochemical, PCR and sequencing using specific primers to this species, and pathogenicity test. This information is essential to provide a proper control on the symptom chili plants in Indonesia. 42 Gaining insight into the life cycle and mating system of the floral smut Ustilago quitensis, a prospective biocontrol agent against invasive pampas grass in New Zealand. Probst C1, Bellgard S2 1Manaaki Whenua - Landcare Research, Auckland, New Zealand, 2Northern Territory Department of Industry, Tourism and Trade, Darwin, Australia Pampas grass, a perennial grass native to South America, is invasive in multiple regions including New Zealand, Australia, South Africa, the United States, and parts of Europe. In New Zealand, two species of Pampas grass, Cortaderia jubata and C. selloana, can form dense stands, outcompeting native plants. In 2012-2013, surveys for potential biocontrol agents were conducted within its native range. A floral smut fungus, Ustilago quitensis, was discovered in Ecuador and later in Chile. The fungus was imported to Manaaki Whenua – Landcare Research's plant pathogen containment facility in Auckland in 2017, where its life cycle is currently being studied. On artificial media, teliospores produce haploid sporidia that are unable to infect plants unless they fuse with sporidia of the opposite mating type. A method to determine compatible smut mating types, combining two sporidial types on charcoal media, was tested, but proved unsuccessful. To understand the mating system of U. quitensis, specific primers were designed to target its mating-type loci. This revealed the presence of four different mating-types, indicating that the life cycle of U. quitensis is regulated by two independent mating type loci, similar to Ustilago maydis. Three-year-old pampas seedlings were injected with a 0.5 mL spore suspension containing two different mating-types and were harvested 20 months later. Due to the difficulty of inducing pampas plants to flower under controlled glasshouse conditions, a species-specific, real-time PCR (TaqMan) assay was developed to detect U. quitensis in plant tissues. This assay identified the presence of the smut fungus in the stems of the “inoculated” plants. The smut was only detected in plants inoculated with the opposite mating types, confirming the effectiveness of the inoculation method to enable infection, and the specificity of the PCRs designed to determine the U. quitensis mating types. Session 1 D: Integrated Disease Management/ Biological Control 15 The benefits of breeding major food crops for durable resistance: A meta-analysis of empirical evidence Geffersa A1, Barrett L1, Sprague S1 1CSIRO Agriculture and Food, Canberra, Australia The benefits of breeding major food crops for durable resistance: A meta-analysis of empirical evidence Abstract A critical challenge for food security is to protect crops from damage caused by microbial pathogens. Breeding crops for disease resistance is a sustainable approach to meeting this challenge. However, pathogen adaptation, leading to the breakdown of resistance, is common and can cause damaging outbreaks of disease. While the importance of genetic, evolutionary and epidemiological factors to managing resistance breakdown are reasonably well understood, there has been little effort to understand the parallel socio-economic dimension. Consequently, incentives for individual decision-makers to invest in managing pathogen evolution are often difficult to articulate or support with solid evidence. We will present research investigating how socio-economic factors influence the management of genetic resistance and pathogen evolution. We first develop a conceptual framework that illustrates the socio-economic challenges to proactively managing resistance ineffectiveness. We extend our conceptual model with a meta-analysis of the agronomic and economic impacts of the adoption of disease-resistant crops worldwide to consolidate empirical evidence. Our assessment highlights that resistance delivers considerable economic and agronomic benefits. However, such benefits will only be fully realized if a significant effort is put into the identification of effective incentives for the adoption and uptake of resistance deployment strategies to increase resistance durability. Keywords: Economic benefits; food security, genetic resistance; pathogen evolution; plant systems 201 Endophytic actinobacteria as a biocontrol agent of stem canker disease of royal poinciana caused by Neoscytalidium dimidiatum El-Tarabily K1, AbuQamar S1, Almazrouei H1, Allabban S1 1College of Science, United Arab Emirates University, Al-Ain, United Arab Emirates Twenty-seven endophytic streptomycete and non-streptomycete actinobacteria were isolated from healthy royal poinciana root tissues. In vitro screening revealed that the antifungal action of isolate #14 was associated with the production of cell-wall degrading enzymes; whereas with diffusible antifungal metabolites in isolate #21, albeit their production of volatile antifungal compounds. According to the 16S rRNA gene sequencing, isolates #14 and #21 were identified as Streptomyces spp. The two antagonists recovered from root tissues till 12 weeks after inoculation, efficiently colonized root cortex and xylem vessels, indicating that the royal poinciana roots are a suitable habitat for these endophytic isolates. At the end of the greenhouse experiments, the development of stem canker disease was markedly suppressed by 52% with the application of isolate #14 and 62% with isolate #21, confirming their potential in disease management. Results showed that the estimated disease severity indices in diseased seedlings were significantly (P<0.05) reduced from 4.64 (scale of 5) to 1.05 or 0.51 by either isolate #14 or isolate #21, respectively. In addition, conidial numbers of the pathogen significantly (P<0.05) dropped by 55% and 82% with isolate #14 or isolate #21, respectively, compared to infected seedlings with Neoscytalidium dimidiatum (control). Thus, the suppression of disease symptoms was superior in seedlings pre-inoculated with isolate #21, indicating that the diffusible antifungal metabolites were responsible for N. dimidiatum retardation in these plants. This is the first report of actinobacteria naturally existing in royal poinciana tissues acting as microbial antagonists against stem canker on royal poinciana. 110 Management of chickpea Ascochyta blight using cultivar resistance, fungicide strategies and agronomy Fanning J1, Brand J1, Munoz Santa I2,3, McDonald L1, Mawalagedera S1, Taylor J2, Hobson K4, Hollaway G1 1Agriculture Victoria, Horsham, Australia, 2School of Agriculture, Food and Wine, University of Adelaide, , Australia, 3Department of Statistics and Operations Research, University of Valencia, , Spain, 4New South Wales Department of Primary Industries, Tamworth, Australia Chickpea production is limited by Ascochyta blight (Ascochyta rabiei), globally. To reduce yield losses and manage disease, fungicides are essential, as there is limited cultivar resistance. To assist Australian growers managing Ascochyta blight, three sets of experiments were conducted across three seasons in Victoria: 1) Assessment of cultivar resistance with 14-20 cultivars in each experiment, 2) Fungicide strategies, with eight strategies assessed, including single and dual active fungicides (Groups M4, M5, 3, 7, 11, 12), with dual actives (3&11, 3&7) applied preventatively (before rainfall) or curatively (after disease is detected), and 3) Interrow sowing chickpea between a standing or slashed cereal stubble. All experiments had Ascochyta blight, with varying disease severities. Grain yield losses varied across seasons and environments, with losses ranging from 5% to 95%, between cultivars in the absence of fungicides. All fungicide strategies reduced disease severity and grain yield losses, but both the severity and yield loss varied between actives and timings. An economic analysis was inconclusive in determining an optimal strategy,but did provide growers with multiple options for managing disease. Applying dual active fungicides curatively or preventatively did not provide a conclusive result either. This approach combined with cultivar resistance worked economically in drier environments, but not in wetter environments. Grain yield losses could also be reduced with sowing chickpeas between standing cereal stubble rows. These experiments highlighted the importance of individual factors on reducing grain yield losses, including cultivar resistance, fungicide applications, and inter row sowing. However further research is required to determine the advantage of combining all these factors. 13 Taking shortcuts: modifying harvest height to prevent colonisation of cereal stubble by Fusarium pseudograminearum Petronaitis T1, Forknall C3, Simpfendorfer S1, Flavel R2, Backhouse D2 1NSW DPI, Calala, Australia, 2University of New England, Armidale, Australia, 3Department of Agriculture and Fisheries, Toowoomba, Australia Higher harvest-heights (e.g., via stripper headers) and rotations with shorter stature break crops such as chickpea (Cicer arietinum) are being increasingly adopted with wheat production in the northern grain region of Australia (NSW and Qld). These practices have potential to affect the saprotrophic colonisation, survival and/or dispersal of Fusarium pseudograminearum (Fp) in cereal stubble. Thus, three-year field experiments at two sites in northern NSW were conducted to explore the effect of stubble height on saprotrophic colonisation of Fp-inoculated durum wheat stubble (2019-20 season). Dispersal of Fp inoculum following harvest of a chickpea break crop (2020 season) and any subsequent effects on FCR risk (2021) were also assessed. A combination of culturing and quantitative polymerase chain reaction (qPCR) methods was used. Cutting stubble short (13-17 cm in height) prevented any further colonisation of stubble by Fp occurring after harvest. In comparison, taller stubble (approximately 38-45 cm in height) allowed 61 to 70% more vertical progression of Fp within the infected stubble in the 6 months after harvest. The pathogen also persisted higher within the stubble for at least 12 months after harvest (compared with the height found at harvest). Significant displacement of Fp was observed in the basal (crown) portion of durum stubble from six months post-harvest, resulting in large decreases in total Fp DNA concentrations in stubble. As such, no significant differences in FCR risk (PREDICTA® B) were observed for the different stubble management scenarios. Still, this research provides important field-validation that saprotrophic colonisation of standing cereal stubble by Fp is occurring in the northern region, which can potentially be prevented via harvest height modification. 66 Elucidation of antagonistic mechanisms of Bacillus velezensis in biocontrol of shot-hole disease in flowering cherry Han V1,3, Yu N1, Yoon H2, Ahn N2, Son Y2, Lee B2, Kim J1 1College of Agriculture and Life Sciences, Chonnam National University, Gwangju , Republic of Korea, 2Biological and Genetic Resources Assessment Division, National Institute of Biological Resources, Incheon , Republic of Korea, 3Centre for Crop and Disease Management (CCDM), Curtin University, Bentley, Australia The shot-hole disease is among the most important diseases affecting flowering cherry (Prunus x yedoensis Matsumura) trees in South Korea every year, resulting in spots and shot-holes in the leaves. Several pathogens are associated with the disease, including the bacteria Bukholderia contaminans, Pseudomonas syringae pv. syringae, and Xanthomonas arboricola pv. pruni, and the fungi Mycosphaerella cerasella and Epicoccum tobaicum. This study aimed to investigate the inhibitory activities of antagonistic bacteria against shot-hole pathogens both in vitro and in vivo and their bioactive compounds. Of the 403 bacterial strains isolated, two biosurfactant-producing bacterial strains, designated as JCK-1618 and JCK-1696, exhibited the best effects against the growth of both bacterial and fungal shot- hole pathogens in vitro through their cell-free culture filtrates (CFCFs). These two strains were identified as Bacillus velezensis based on morphological characteristics and sequence analysis of 16S rRNA (ribosomal ribonucleic acid) and gryA (DNA gyrase subunit A) gene. In addition, they strongly inhibited the growth of the pathogens via the action of their antimicrobial diffusible compounds and antimicrobial volatile organic compounds (VOCs). Crude enzymes, biosurfactants, and solvent extracts of the two strains also exhibited antimicrobial activities. Liquid chromatography/electrospray ionization time-of-flight mass spectrometric analysis of the partially purified active fractions, obtained from the CFCFs of both JCK-1618 and JCK-1696, revealed that the two antagonists produced three cyclic lipopeptides, including iturin A, fengycin A, and surfactin, and a polyketide, oxydifficidin. In a detached leaf assay, pre-treatment and co-treatment of flowering cherry leaves with the CFCFs led to a large reduction in the severity of the leaf spots caused by E. tobaicum and Bu. contaminans, respectively. To our knowledge, this is the first report of the antimicrobial activities of the diffusible compounds and VOCs of B. velezensis against the shot-hole pathogens and their efficiency in the biocontrol of shot-hole in flowering cherry. 67 Identification of Pyrenophora teres f. teres virulence QTL with multi- parental and bi-parental mapping populations Dahanayaka B1, Martin A1 1University of Southern Queensland, Toowoomba, Australia Net-form net blotch (NFNB) is an economically important disease, causing severe yield losses in susceptible barley varieties. This foliar disease is caused by the fungal pathogen Pyrenophora teres f. teres (Ptt). Multi-parental nested association mapping (MP-NAM) and bi-parental mapping populations consisting of 399 and 305 progeny isolates of Ptt, respectively, were developed with the aim to identify quantitative trait loci (QTL) associated with Ptt virulence on the barley cultivars Prior and Skiff. The effectiveness of using a MP- NAM population to identify QTL in haploid plant fungal pathogens like Ptt was also assessed. The MP-NAM population consisted of four inter-crossed sub-populations. The four populations were developed by crossing parental isolates virulent to Prior with isolates avirulent to Skiff and vice versa. The bi-parental mapping population was developed by crossing two of the Ptt isolates also used in the MP-NAM crosses. A highly significant QTL for Prior virulence was identified on chromosome 5 in both the MP-NAM (LOD from 30.9 to 36.7) and the bi-parental (LOD 48.0) populations. The phenotypic variance explained by the QTL ranged from 33 to 63% in the MP-NAM population and 40% in the bi-parental mapping population. For Skiff virulence, a QTL was identified on chromosome 3 with LOD values ranging from 8.9 to 9.9 in the MP-NAM populations and a LOD of 22.0 in the bi-parental population. The phenotypic variation explained by the QTL in MP-NAM was 13% and bi- parental was 24%. The MP-NAM population detected eight QTL in total whilst only five QTL were detected with the bi-parental mapping population. The result of this study confirms that MP-NAM populations can be successfully used in detecting QTL in haploid fungal pathogens and are especially useful when individual crosses produce insufficient numbers of ascospores for bi-parental mapping analyses. Session 2 A: Molecular Plant Disease Interactions 52 How does a broad host range necrotrophic fungal pathogen trigger host cell death? Newman T1, Kim H2, Khentry Y1, Sohn K2,3,4, Derbyshire M1, Kamphuis L1 1Centre for Crop and Disease Management, Curtin University, Bentley, Australia, 2Plant Immunity Research Center, Seoul National University, Seoul, Republic of Korea, 3Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea, 4Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea Sclerotinia sclerotiorum is a fungal pathogen that infects a wide range of crop species, causing significant economic damage. This pathogen produces small effector proteins to kill host cells and obtain nutrients. Our objective was to discover novel necrosis-inducing effectors and characterize their activity using transient expression in Nicotiana benthamiana leaves. Five intracellular necrosis-inducing effectors were identified with differing host subcellular localization patterns. Notably, we discovered that one of the effectors enters host cells using an RxLR-like motif. Additionally, we found evidence that another effector induces necrosis via an NLR protein. All five of the identified effectors are highly conserved in globally sourced S. sclerotiorum isolates. These findings contribute to our understanding of how S. sclerotiorum causes disease and reveal potential opportunities for developing genetic resistance against this damaging fungal pathogen. 175 The Effect of Endophytic Fusarium oxysporum on the rhizome quality of ginger (Zingiber officinale Roscoe) Matthews A1, Aitken E1 1The University Of Queensland, Ormiston, Australia There are approximately 1500 species of plants belonging to the family Zingiberaceae. Many of these species are used for food, including ginger, turmeric and cardamon but some also contain compounds with medicinal properties with potential to treat illnesses such as nausea, blood conditions and cancer. Ginger (Zingiber officinale Roscoe) is both an important spice and a source of gingerol, an aromatic compound extensively used in traditional medicine. Ginger is grown widely in tropical and subtropical countries, including Australia. Despite the presence of antimicrobial compounds like gingerol, soil borne diseases, including Fusarium oxysporum f. sp. zingiberi (Foz) can cause significant discolouration and damage to ginger rhizomes. In our study, ginger rhizomes were found to host both pathogenic Foz and non-pathogenic fusaria. Our studies have also found that Foz carries secreted in xylem (SIX) genes, SIX7, SIX9, SIX10 and SIX12, but the non-pathogenic, endophytic fusaria in our study did not carry SIX genes. In order to better understand the role of SIX genes in host-pathogen interactions, we inoculated ginger with Foz; with Fusarium oxysporum f. sp. dianthi (Fod), a carnation pathogen reported to carry the same SIX gene profile as Foz; with Fusarium oxysporum f. sp. niveum (Fon), a watermelon pathogen with a different SIX gene profile; and a Fusarium oxysporum endophyte isolated from ginger. It was found that the ginger endophyte and Fon had little effect on rhizome quality, but that rhizome quality was reduced by Foz and Fod. Gingerol is produced via the phenylpropanoid pathway, a process associated with plant defence. While the presence of pathogens would be expected to increase gingerol levels, it is proposed that non-ginger pathogens could be used to stimulate gingerol production without reducing rhizome quality. Further research is required to quantify changes in gingerol production in the presence of pathogenic and non-pathogenic fusaria. 120 A cornucopia of signaling factors in R-mediated defense against viral pathogens allows new types of regulation to fit the occasion Palukaitis P1 1Jeonbuk National University, Jeonju, South Korea Dominant R-mediated defense against various plant pathogens occurs largely via effector triggered immunity (ETI). This can involve various pathways including those regulated by phytohormones (SA, JA, ET, ABA, NO, BR, and AUX), MAP kinase cascades, lipase-like regulator proteins (EDS1, PAD4, and SAG101), other regulator factors (NDR1/HIN1, and NPR1), transcription factors (WRKYs, MYBs, ERFs, and NACs), plant effector proteins (PR proteins, AGOs, IVR, and RDRs) and helper CNLs (ADR1, NRG1, and NRC2/3/4). Activation of the defense responses occurs following conformational changes in the R-proteins, mediated by one or more chaperones (HSP90, SGT1, RAR1). Analysis of the early steps in the five most characterized R gene response signaling pathways [TMV/N/N.tabacum(Nt); PVX/Rx/S.tuberosum(St); TCV/HRT/A.thaliana(At); TMV/Tm2²/S.lycopersicum(Sl); and TSWV/Sw5b/Sl] reveals numerous differences: (1) Not all three chaperones are required (TCV/HRT/At, TSWV/SW5b/Sl; unknown for TMV/Tm2²/Sl); (2) no need for EDS1 (PVX/Rx/Sl, TSWV/SW5b/Sl; unknown for TMV/Tm2²/Sl); (3) no need for NPR1 (TCV/HRT/At, TSWV/SW5b/Sl; unknown for PVX/Rx/Sl, TMV/Tm2²/Sl); (4) no need for NGR1 (TSWV/SW5b/Sl; unknown for TCV/HRT/At, TMV/Tm2²/Sl); (5) no need for ARD1 (TSWV/SW5b/Sl; necessary for PVX/Rx/Sl unknown for others); (6) need for NRC2/3/4 (PVX/Rx/Sl, TSWV/SW5b/Sl; unknown for others); (7) no need for NDR1 (TCV/HRT/At, TSWV/SW5b/Sl; unknown for others); (8) need for CRT1 (PVX/Rx/Sl, TCV/HRT/At; unknown for others); (9) need for MIP1a (TMV/N/Nt, TMV/Tm2²/Sl; unknown for others); and (10) additional factors identified for one system, but not examined in others (SPL6 in TMV/N/Nt; RanGAP2 in PVX/Rx/St; DRB1/4 in TCV/HRT/At). These observations indicate there is much variation in the regulation of early steps in the signaling pathways, as well as alternative approaches that can be used or better fitted to specific R proteins. In addition, these data show that it is not possible to predict what components from the ensemble available will be used by a specific R protein, and therefore each system needs to be examined separately. 93 The ilv2 gene, encoding acetolactate synthase for branched chain amino acid biosynthesis, is required for pathogenicity in Leptosphaeria maculans Chong N1, Idnurm A1, Van de Wouw A1 1University of Melbourne, Melbourne, Australia Control of blackleg disease of canola caused by the fungus Leptosphaeria maculans relies on strategies such as the inhibition of fungal growth with fungicides. However, growers use other chemicals during canola cultivation, including fertilizers and herbicides, that may inadvertently impact the fungus. Based on widespread use of herbicides that target the acetolactate synthase (ALS) enzyme involved in branched chain amino acid synthesis and evidence of low levels of these amino acids within leaves of Brassica species, here the impact of a commercial herbicide targeting ALS and mutation of the target ilv2 gene in L. maculans was explored. Exposure to herbicide had limited impact on growth in vitro but reduced lesion sizes in plant disease experiments. Mutation of the ilv2 gene via CRISPR- Cas9 gene editing rendered the fungus non-pathogenic. Hence, herbicide applications can influence disease outcome, but likely to a minor extent with current chemicals. 78 Ascochyta rabiei effector molecules in different tissue type of chickpea by using transcriptomics Monsur M1, Bar I1, Ford R1 1Centre for Planetary Health and Food Security, Griffith University, Brisbane, Australia Ascochyta blight of chickpea, caused by Ascochyta rabiei, is one of the most important foliar diseases in chickpea, with substantial worldwide economic impact on production quality and yield. Foundational research on plant-pathogen molecular interactions have provided clues to the molecular mechanisms underlying A. rabiei infection in early stage of chickpea seedlings. These studies identified several signaling molecules (effectors) and transcription factors that have been suggested to play key roles in the infection and establishment of the pathogen, leading to disease. The aim of this study was to reveal the differential genomic controls and mechanisms underlying molecular mechanisms of A. rabiei when in contact with different tissue types (leaf and pod) of chickpea. For this, a dual RNA-Sequencing approach was chosen to compare the transcriptomic responses of pathogen while infecting the vegetative or reproductive tissues. The identified differentially and co-expressed sequences were then functionally annotated using the ME14 (NCBI accession GCA_004011695.2) A. rabiei genome reference sequence as well as homology and domain searches and cross-referenced to a database of A. rabiei predicted effector proteins using the featureCounts output count matrix using the R (v3.6.1; R Core Team, 2018) package edgeR v3.26.8 as implemented in Degust v4.2-dev. The results of this study will help to identify for novel genes/effector sequences that are differentially expressed at maturity growth stages, including on reproductive host tissue. This will aid in unraveling a better understanding of the pathogen’s strategy to overcome host defences when the crop is most advanced in the field. 165 Soilborne pathogens influence on plant-microbiome interactions: cause and effects Gupta, V.V.S.R.1,4, Smith, L.2, Greenfield, P.3 Regmi, R.1,4 and Penton, C.R.5 1CSIRO Ag & Food, Glen Osmond, Australia, 2Qld DAF, Brisbane, Australia, 3CSIRO Energy, North Ryde, Australia, 4CSIRO MOSH-FSP, Glen Osmond, Australia, 5Arizona State University, Mesa, United States of America Plant root-associated microbiomes in the endosphere and rhizosphere environment are integral to the phenotypic performance of host plants and pathogen interactions with plants and microbiomes in rhizosphere – root environment play an important role in the composition of root microbiome and overall functional outcome. While the root associated microbiomes are known to influence plant-pathogen interactions and disease incidence, infection of host plant by soilborne fungal pathogens can also influence the diversity and composition of root microbiomes. We investigated the changes in rhizosphere and endosphere bacterial (16S) and fungal (ITS region) community composition and diversity as influenced by fungal pathogens Rhizoctonia solani AG8 in wheat and Eutypella sp in cotton plants using group specific amplicon sequencing. Results from the beta diversity analysis of rhizosphere bacterial and fungal communities indicated significant changes in the presence of high levels of R. solani with responses in specific members and groups of bacteria and fungi and the changes were more dramatic with the addition of chitin substrate. Pathogen presence also decreased alpha diversity in the presence of plant. Results for Eutypella sp. infected cotton roots indicated significant reduction in the total fungal community diversity, with two Eutypella OTUs accounting for 45-99% of all sequences including displacement of other fungi including mycorrhizae. Overall, this work demonstrates that infection by fungal pathogens can cause drastic changes in root associated bacterial and fungal communities in terms of diversity and composition, directly through displacement of other microbes and/or through modulation of plant-microbiome signaling pathways. Session 2 B: Microbiomes and Disease Complex 144 Metatranscriptomics captures functional dynamics between the plant and its microbiome Law S1 1Microbiomes for One Systems Health - CSIRO , Canberra, Australia Recent advances in DNA and RNA sequencing technologies have provided an unprecedented view of the complex microbial communities that populate our bodies and surroundings. For plants, these microbial communities (microbiomes) are sources of both essential mutualistic services and devastating pathogens. Metatranscriptomics captures the active gene expression profiles of complex microbial populations and their host simultaneously, revealing dynamics in community structure (who is there?), functions (what are they doing?), and their coordination with host processes. This talk will present a metatranscriptomic case study and discuss ongoing applications of this approach to build predictive frameworks that will guide strategic agricultural practices. 177 Measuring the impacts of deep tillage on soil biological health Linsell K1, Davies S2, Mwenda G3, Flower K4, Hayden H5, Collins S6 1South Australian Research and Development Institute, Adelaide, Australia, 2Department of Primary Industries and Regional Development, Geraldton, Geraldton, 3Department of Primary Industries and Regional Development, Northam, Australia, 4University of Western Australia, Perth, Australia, 5The University of Melbourne, Melbourne, Australia, 6Department of Primary Industries and Regional Development, Perth, Australia Large areas of Australian agricultural land are affected by numerous soil constraints including water repellence, low pH, subsoil compaction, salinity, sodicity and low organic matter. Soil amelioration techniques, including strategic deep tillage can help alleviate these constraints to improve productivity. Common mechanical amelioration techniques, including soil mixing (rotary spading), soil inversion (mouldboard ploughing) and deep ripping, all lead to various degrees of soil redistribution, creating changes to the soil’s physical and chemical profile. These actions also mix the soil’s biological organisms, but little is known about the impact on soil biological health. It is difficult to measure soil biology due to its large size and complexity. Nematode communities are good bioindicators and are routinely used to monitor the biological status of soils. SARDI has developed a suite of 15 DNA tests that cover the five major free-living nematode (FLN) feeding types. The abundance and diversity of nematode feeding groups reflects the underlying structure of the soil microbial community and can be used to diagnostically assess soil biological health. The impacts of deep tillage techniques on soil biological status were investigated at several field trials on deep sand and sandy gravels in Western Australia’s grainbelt using FLN DNA soil tests. The treatments (inversion, deep ripping and mixing) improved soil biological health between 10-30cm in depth with increases in all FLN taxa compared to control treatment, and these positive effects were observed up to 3 years post amelioration. At the surface 0-10cm layer, there were no significant effects on FLN communities except in the inversion treatment which decreased total FLN. At the deeper 30-40cm depth there was little to no FLN community present in any treatment. 19 Soil disease suppression in the omics world: From small RNA molecules to HiC genomics Regmi R1,3, Anderson J1,2, Hicks M1,3, Kroker S3, Vadakattu G1,3 1Microbiome for One Systems Health (MOSH), CSIRO, Adelaide, Australia, 2Agriculture and Food, CSIRO, Perth, Australia, 3Agriculture and Food, CSIRO, Adelaide, Australia The rhizosphere microbiome is critical in maintaining plant health, supplying nutrients, and defence during abiotic stress. In addition, some soils possess a microbiome able to suppress soil-borne disease development. Given the importance of microbial communities in suppressing agricultural diseases, investigation of the edaphic and plant host-derived factors affecting the composition and function of these communities is essential. Thus far, root biochemical exudates have been identified as a central controller of the rhizosphere microbiome assembly. As a part of the CSIRO Microbiome for One System Health (MOSH) rhizosphere project, we are investigating how bacterial and root-secreted nucleic acids drive plant-microbiome interaction below ground. To do so, we applied multi-omics studies (sRNA profiling, Metagenomics, and Transcriptomics) to understand the assembly, composition, and function of microbiomes in disease-suppressive and non-disease suppressive agricultural soils. Our results indicate that sRNA profiling in the rhizosphere-microbiome can enhance our understanding of plant - microbiota communication. Furthermore, sRNA datasets could predict the microbiome taxonomy profile as comparable to metagenomics assembled taxonomy. Knowledge gained through integrated metagenomics, transcriptomics, and sRNA profiling will help to develop cropping systems with disease suppressive capacities through in-situ development of suppressive communities, modification of host genetics/immunity to support disease suppression and/or development of synthetic communities conferring stable disease suppression. Keywords: Small RNAs, microbiome, soil disease suppression, multi-omics 61 Harnessing microbial allies for successful pine growth under pathogen pressure. Chowdhury J1, Senior J2, Elms S3, Plett K4, Plett J1 1Hawkesbury institute for the environment, Western Sydney University, Richmond, Australia, 2HQPlantations, , Australia, 3HVP Plantations, , Australia, 4NSW Department of Primary Industries, Sydney, Australia Early attempts to introduce pine plantation forestry in Australia during the nineteenth century faced failure, partly due to the absence of essential microbial allies, such as ectomycorrhizal fungi. These fungi play a crucial role in nourishing plants with vital nutrients that would otherwise be inaccessible, while also providing protection against pathogenic invaders. Recognizing the ecological significance of microbial symbiosis, it has become essential to promote beneficial microbiomes during growth of seedlings in pine nurseries. However, the full potential of diverse microbial associations in enhancing ecosystem functioning and promoting sustainable reforestation practices remains largely untapped. In collaboration with Australian pine nurseries in four states, we are investigating how young Pinus radiata and Southern pines treated with functionally diverse microbial inoculum perform under low fertilizer and fungicide application with or without disease pressure (Fusarium and Botrytis) as compared to routine nursery application. Our data reveal that, despite receiving reduced level of nutrition, seedlings treated with organic fertilizer and functional microbes exhibit enhanced photosynthetic rates, greater growth, and increased biomass compared to those treated using standard nursery practices. Furthermore, mycorrhizal association increases under disease pressure. With multi-omics approaches, we delve deeper in to underlying molecular mechanisms by which seedlings benefit from organic fertilization in association with microorganisms under pathogen pressure, as well as the specific roles played by each microbial species in this association and paving the way for sustainable reforestation practices. 191 One vine, two diseases: Interactions of different fungal trunk pathogens associated with Botryosphaeria dieback and Petri disease complex in Australian vineyards Amorio D1, Billones-Baaijens R2, Stodart B1,2, Savocchia S1,2 1Faculty of Science and Health, School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University , Wagga Wagga, Australia, 2Gulbali Institute, Charles Sturt University, Wagga Wagga, Australia Grapevine trunk diseases (GTDs) remain a significant threat to vine yield and sustainability. Recent studies utilising microbial profiling demonstrated that the pathogens associated with two significant GTDs, Botryosphaeria dieback (BD) and Petri disease (PD), were present together in individual vines, with PD pathogens being the most abundant. The incidence and impact of PD has not been comprehensively studied in Australia, while being considered a serious disease in Europe. This study investigated the in vitro interactions between the pathogens associated with BD and PD disease complexes by dual inoculation. Within BD and PD complexes, mycelial plugs from the actively growing margin of the pathogens were inoculated, simultaneously, 4 cm apart onto culture media, while for between pathogen groups (BD x PD), PD pathogens were inoculated two weeks prior to co-inoculation with BD pathogens. The plates were incubated at 25° in total darkness for 7-30 days and assessed for morphological characteristics and fungal growth. Within the BD complex, a change in colour and formation of a dark-pigmented margin was observed when Diplodia seriata was paired with Neofusicoccum parvum in comparison with its control. Although morphological changes were observed in this interaction, no significant differences were observed in paired and self-paired growth rates. Between pathogen groups, a significant reduction in the average fungal growth was observed between Phaeoacremonium aleophilum and N. parvum and formation of an inhibition zone between P. aleophilum and D. seriata. The morphological changes in vitro revealed specific interactions between BD and PD pathogens, which require further examination in vivo. Investigating the interaction of GTD pathogens will provide critical data to assist in understanding disease epidemiology, forming the basis of improved management strategies. 121 Xanthomonas campestris pv campestris: What have we learnt over the past four years Chapman T1, Lidbetter F2, Webster J1, Bogema D1, Snijders F1, Jarvis J1, Mulholland S1, Wong J1, Okoh E2, Tesoriero L1 1NSW Department Of Primary Industries, Menangle, Australia, 2Western Sydney University Brassicas are one of the dominant vegetable crops grown in NSW with an annual value of $36.7M. Black rot, caused by Xanthomonas campestris pv campestris is considered the most devastating disease globally. This seedborne pathogen, once established in a crop, can decimate marketable yield as there are no effective treatment options. It thrives in climatic conditions of rain, humidity and temperate conditions, yet is still a problem in low temperatures. Small landholders in NSW are not able to effectively rotate crops to reduce pathogen load, giving the advantage to the pathogen. This means that the pathogen likely remains on farm perennially and is continually reintroduced with new seed stock/seedlings. As management is the main option for growers, we needed to address some fundamental knowledge gaps about this pathogen. This study investigated the genetic diversity of the historical X. campestris culture collection in Australia and compared their genetic diversity to isolates found globally and surveillance isolates collected over the past four years. We then selected representative clonal types for pathogenicity assays to investigate the relationship between genetic diversity and pathogenicity in different brassica types and to develop a new assay for the specific detection of X. campestris pv campestris. The longevity of a pathogen on a farm is another key question for a seedborne pathogen like X. campestris. An experiment to determine how long X. campestris was able to survive in plant material when buried below the soil or left as debris on top of the soil was monitored for 12 months, and the viability of the pathogen determined through pathogenic assays. These results with those from surveillance helped determine if X. campestris are remaining on farm or are being continually reintroduced. This study improves our understanding of this pathogen immensely and equips us with more tools in black rot management. Session 2 C: Plant Disease Management, Chemical Resistance 92 Detecting fungicide resistance mutations in Pyrenophora teres using a portable DNA sequencer Zulak K1, Farfan-Caceres L1, Knight N1,2, Lopez-Ruiz F1 1Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, Australia, 2Centre for Crop Health, University of Southern Queensland, Toowoomba, Australia Fungicide resistance remains a threat to food security with resistance to demethylase inhibitor (DMI) fungicides being particularly problematic. The gene encoding the DMI target sterol 14α-demethylase (Cyp51) has evolved an array of mutations in both the promoter and coding sequence in two closely related barley pathogens, Pyrenophora teres f. teres (Ptt) and P. teres f. maculata (Ptm). Detection of resistance mutations using allele-specific amplification-based technologies relies on one assay per mutation and all assays must be run on every sample increasing the time and cost of detection. Also, uncharacterised mutations will not be detected which requires the use of sequencing pipelines. To improve the speed of mutation detection, we developed an amplicon sequencing based approach using a combination of the Oxford Nanopore Technologies MinION portable DNA sequencer and unique molecular identifiers (UMIs) for sequencing error correction. We profiled resistance mutations in pure isolates of Ptt and Ptm and a hybrid and detected all known mutations with SNP-level accuracy with built-in chimera filtering, which is especially important for accurate genotyping of complex samples where amplicons may differ by only a few SNPs. We have expanded the utility of our pipeline by including three genes encoding the targets of succinate dehydrogenase inhibitor (SDHI) fungicides and detected mutations associated with reduced sensitivity or resistance to both modes of action directly from infected leaf samples. This method is broadly applicable to other systems where resistance is problematic including weeds, insects, and human pathogens. 173 Managing the unmanageable – understanding the role of seedborne Ramularia collo-cygni as a source of disease spread in New Zealand barley crops. Drummond J1, Warren R2, Thompson S2, Joshi M2, Liu J2, Chng S2 1Foundation For Arable Research, Christchurch, New Zealand, 2The New Zealand Institute of Plant and Food Research Limited, Christchurch, New Zealand The lack of any substantive genetic resistance or tolerance to Ramularia leaf spot (RLS) of barley and the emergence of reduced sensitivity to Group 7 and 11 fungicides in New Zealand’s Ramularia collo-cygni (Rcc) population has resulted in a drive to find alternative disease control strategies. The prevalence of seedborne Rcc inoculum was studied in surveys of post-harvest grain collected from 2017 to 2020. Assays detected Rcc DNA on almost all samples, regardless of season, location, cultivar, sowing date, rotation position, irrigation, prior fungicide programme or in-field RLS severity, suggesting seedborne Rcc inoculum could be epidemiologically important. Despite Rcc DNA being detected in almost all surveyed grain samples, the amount of seedborne inoculum reduced more than 100,000 times from 2017 to 2020. This implied that different management strategies across the sampling period may have impacted quantities of seedborne inoculum. Subsequent field trials identified fungicide programmes that reduced the amount of Rcc transmitted to the progeny seed, which resulted in reduced disease severity on progeny plants. Glass house studies protected from seasonal infection followed persistence of Rcc inoculum on barley seed over multiple generations. Seedborne DNA in this study was detected for three generations, confirming Rcc could persist as a source of ongoing contamination. However, the incidence and amount of detectable inoculum decreased on seed with each generation, resulting in Rcc DNA being detected in only 16% of G2 and 3% of G3 seed samples grown from the original (G0) infected seed. Together these data suggest seedborne inoculum of Rcc can persist, creating a source of infection in subsequent crops, but use of an effective fungicide programme on the preceding barley crop can help to reduce this initial inoculum source and RLS. These programmes all included mixtures of multiple fungicide mode-of-action groups, which could reduce selection for further loss of chemistry. 213 Enhancing Hot Pepper Production in the Southwest US: Field Evaluation of Advanced Varieties for Disease Resistance Sanogo S1, Crosby K2, Dobey Q1, Fechner J1, Leskovar D1, Jifon J2, Fedio W1, Acharya R1 1New Mexico State University, 2Texas A&M AgriLife Hot peppers (Capsicum spp.) are of a great ethno-botanical and economic importance in southwestern United States, particularly in Arizona, California, New Mexico, and Texas. Domestic production of hot peppers faces competition from imports from other hot pepper- production regions, and is constrained by high labor and input costs, and abiotic and biotic stresses. A multi-state project was initiated in 2019 involving Texas AgriLife and New Mexico State University, with sponsorship from the USDA-Agriculture Marketing Service, Specialty Crop Multi-State Program through Texas Department of Agriculture, to optimize production of hot pepper production in the U.S. One specific objective of the project is to monitor high- yielding advanced varieties for resistance to plant pathogens. In the growing seasons of 2020, 2021, and 2022, several advanced varieties from the Texas AgriLife Breeding Program were planted in southern New Mexico in growers’ fields and monitored for development of diseases. Across all three seasons, disease types and disease pressure were variable. Diseases encountered consisted of chile wilt caused by Phytophthora capsici, Verticillium dahliae, and Rhizoctonia solani. The incidence of chile wilt was 1% to over 20% across fields. Other diseases found were caused by viruses (Beet curly top virus, Alfalfa mosaic virus, and Tomato spotted wilt virus), bacteria (bacterial leaf spot, caused by Xanthomonas euvesicatoria), and powdery mildew (caused by Leveillula Taurica). The incidence of viral and bacterial diseases was at 1% to over 50% across all advanced varieties. In the later part of the seasons, powdery mildew was observed in all advanced varieties, at 100% incidence (at field level, that is, all plants displayed symptoms of the disease). The severity of powdery mildew (at plant level) was greater than 30% across all varieties. None of the advanced varieties were found resistant across the spectrum of diseases encountered. 68 Biochemical changes in Vitis vinifera leaves and responses to Botrytis cinerea infection after the application of a yeast extract formulate Scimone G1, Nali C1, Bartalena G2, Zerulla F2, Pellegrini E1 1University Of Pisa, Pisa, Italy, 2KWIZDA HOLDING GMBH, Wien, Austria Grapevine (Vitis vinifera L.) is one of the most economically important crops worldwide, and the increase in wine production rate demand requires changes in the agricultural processing and manufacturing practices to make them sustainable. Issues associated with the large use of agrochemicals and consumer needs for residue free products have stimulated research into new and eco-friendly tools for sustainable pest management and vine protection. The aim of the present study (supported by KWIZDA Agro GmbH) was to characterize at functional level the “indirect” protective mechanisms induced by the application of a yeast extract formulate (YE) through the induction of defense responses in V. vinifera cv. Sangiovese plants artificially inoculated with Botrytis cinerea (Bc). In YE+/Bc+ leaves, germ tubes did not elongate well, and their hyphae were slightly spread over the leaves after 2 days. The hydrogen peroxide induction (observed from 1 h post inoculation; +40% compared with YE-/Bc- ones) triggered a production of ethylene and a concomitant accumulation of jasmonic acid (7 fold-higher and +34%, respectively). These results confirm a synergistic action in the regulation of defense reactions. The absence of oxidative stress (as confirmed by the unchanged values of malondialdehyde by-products) and the early activation of a signaling pathway suggest the capability of YE to induce resistance in grapevine against necrotrophic pathogens. Session 2 D: Integrated Disease Management/ Biological Control 103 Understanding the factors influencing the efficacy of biocontrol against plant diseases for an optimal use in the field Bardin M1, Pressecq T1,2, Turc E1,3, Grimonpont M1, Bourgeay J1, Duffaud M1, Troulet C1, Nicot P1 1INRAE Plant Pathology, Montfavet, France, 2INRAE Ecodeveloppement, Avignon, France, 3Groupe Elephant Vert France, Serris, France The control of plant diseases using micro-organisms has been the subject of intensive study over recent decades, leading to the identification and development of biocontrol agents. These biocontrol agents can limit the development or even suppress plant pathogens, and thus protect plants by direct or indirect means. However, their protective efficacy is generally considered to vary according to growing conditions in the field. Despite its obvious advantages, biocontrol is not without its challenges. Among these challenges, understanding their mode of action is essential to better guide their production and formulation. Another challenge is the lack of knowledge about their durability and the factors modulating their protective efficacy, in particular their interaction with plant pathogens in a changing environmental context. Knowledge of the factors influencing their efficacy is essential to better guide their use in the field, and, consequently, in their success as commercial products. Finally, the implementation of integrated protection strategies requires biocontrol to be compatible with other pest and disease control tools, as well as with cropping practices. During the presentation, the different types of microbial biocontrol agents developed against plant diseases in Europe and their main modes of action will be presented. Development of knowledge on the identification of key factors in their protective efficacy and their use in integrated pest management strategies will be discussed. This presentation will also examine research perspectives to promote an effective and durable use of these products in practice. 43 Uncovering soil microbial interactions during the destruction of Fusarium wilt infected banana plants Pattison T1, Gaza H1, O'Neill W2, Shuey T2, Dennis P3 1Department of Agriculture and Fisheries, Queensland, South Johnstone, Australia, 2Department of Agriculture and Fisheries, Queensland, Dutton Park, Australia, 3The University of Queensland, St Lucia, Australia Fusarium wilt Tropical Race 4 (TR4) is a devastating fungal disease caused by Fusarium oxysporum f.sp. cubense (Foc) that affects banana plants. Foc is spread through contaminated soil and planting material. The identification and destruction of infected plants is an important measure in preventing the disease spread. This involves treating the plant and soil with urea to release of ammonia gas with designated destruction zones. The urea application may initially reduce the abundance of Foc but alter soil physicochemical properties, leading to a reduction in soil microbial community diversity and functions, and hence an eventual increase in TR4 within the destruction zone. An investigation of three destruction zones on a commercial banana farm revealed significant increases in the soil nitrate-nitrogen three months after destruction began. Using a qPCR soil test, DNA from TR4 increased during the first 6-months, before declining by 12-months. Significant changes in the soil bacterial community diversity and structure also occurred within the destruction zone. The understanding of the soil microbial interactions occurring within the destruction zone can be used to improve the efficiency in destruction of Fusarium wilt TR4 infected plants, to help slow the spread of the disease. 202 Biological control of Pythium aphanidermatum damping-off disease of cucumber using actinobacteria capable of producing cell-wall degrading enzymes El-Tarabily K1, AbuQamar S1, El-Saadony M2, Alkuwaiti A1, Alahbabi M1, AlShamsi F1, Naser S1, Al Hamad B1 1College of Science, United Arab Emirates University, Al-Ain, United Arab Emirates, 2Department of Agricultural Microbiology, Faculty of Agriculture, Zagazig University,, Zagazig, Egypt Fifty-eight streptomycete and 35 non-streptomycete actinomycetes were recovered from cucumber rhizosphere soil without and with polyvalent Streptomyces phages. Using mycelial (Pythium aphanidermatum) fragment agar, these isolates were screened for the production of cell-wall destroying enzymes. Eighteen potential isolates were tested for their ability to colonize roots. P. aphanidermatum, the causal agent of post-emergence damping- off of cucumber seedlings, was effectively suppressed in vitro by eight isolates with outstanding rhizosphere competence. Actinoplanes philippinensis, Microbispora rosea, Micromonospora chalcea, and Streptomyces griseoloalbus generated in vitro ß-1,3, ß-1,4, and ß-1,6-glucanases and caused hyphae lysis in P. aphanidermatum. None of these produced volatile inhibitors or siderophores. Only S. griseoloalbus produced diffusible inhibitory metabolites, but A. philippinensis and M. chalcea parasitized P. aphanidermatum oospores. These four isolates were then examined singly or in combination in the greenhouse for their potential to control damping-off of cucumber seedlings in soil with or without cellulose amendment. The treatment that included all four isolates in soil modified with cellulose suppressed damping-off much better than all other treatments and was nearly as good as the metalaxyl treatment. The findings suggest that rather than fungicides, a mixture of antagonistic rhizosphere-competent actinomycetes and cellulose amendment could be used to treat this disease in the field. This is the first study to screen rhizosphere- competent non-streptomycete actinomycetes capable of generating cell-wall degrading enzymes for the control of Pythium infections. 186 Crop rotation reduces the outbreak of Panama disease caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 in Lao PDR Sihomchanh B2, Sisouvong C2, Somphanpanya B2, Bandavong A3, Vongsalad S4, Phongoudom C5, Pattison T1 1Department of Agriculture and Fisheries, Queensland, South Johnstone, Australia, 2Horticulture Research Center, National Agriculture and Forestry Research Institute, Vientiane City, Lao PDR, 3Agriculture Section of Vientiane Capital, Department of Agriculture and Forestry, Vientiane City, Lao PDR, 4Agriculture Unit of Pakgnum District, Agriculture and Forestry Office, Vientiane City, Lao PDR, 5National Agriculture and Forestry Institute, Vientiane City, Lao PDR Banana production in Lao PDR is an important export crop as well as supporting the livelihoods of smallholder banana growers. A field experiment was conducted alternating rotation crops with banana in an area with an outbreak Fusarium wilt caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (FOC TR4) in bananas. The experiment was located in longitude and latitude at N18°08´25.14´´; E 102°57´14.68´´, 137 m above sea level, located in Huay Nam Youn Village, Pak Ngum District, Vientiane on a commercial banana farm. Crop rotations with yard longbean, chilli, sticky corn, tomatoes, sweet potatoes and peanuts were used to determine the reduction in the occurrence of FOC TR4 in the following banana crop. Monthly disease incidence and severity observations were made over a 12-month period commencing in June 2021, and terminating in July 2022. The results indicated that corn had a lower percentage of Fusarium wilt incidence of 2.8%, compared with other crop rotation t