The Science Protecting Plant Health Conference was held in Brisbane during September 2017. A partnership between the Australian Plant Pathology Society and the Plant Biosecurity Cooperative Research Centre, conference presentations covered diagnostics, resistance breeding, epidemiology, emerging pests and diseases, biological control, on-farm biosecurity, pest and pathogen surveillance and responding to pest and pathogen incursions.
In this article, we have pulled together the most relevant grains related presentations. You can view the presentation slides by simply clicking on the presentation title.
A ‘genome to paddock’ approach to control plant disease
Presented by Barbara Howlett, Melbourne Uni
Pathogenic fungi evolve in concert with their plant hosts to invade and overcome defence responses. A detailed knowledge of these processes is essential for successful disease management strategies. Blackleg caused by the fungus, Leptosphaeria maculans, is the major disease of canola worldwide. In this lecture I describe how field data, such as disease incidence and severity, coupled with information about the biology, molecular genetics and genomics of the blackleg fungus has been exploited to control this important disease.
Presented by Adnan Riaz, QAAF -QLD Uni
Leaf rust (LR) caused by Puccinia triticina, is an important foliar disease of wheat (Triticum aestivum L.) and the deployment of resistant cultivars is the most viable control strategy. However, P. triticina has the ability to rapidly overcome resistance genes, thus breeders require a constant supply of new sources of resistance. In this study we evaluated a diversity panel of 295 bread wheat accessions from N. I. Vavilov Institute of Plant Genetic Resources (VIR) in St Petersburg, Russia, for LR resistance and performed genome-wide association study (GWAS) using 8, 900 polymorphic DArTseq-GBS markers. The diversity panel was evaluated in 11 environments using three LR pathotypes, prevalent in Australia. GWAS identified a total of 52 significant marker trait associations representing 34 independent quantitative trait loci (QTL). Among them, 32 QTL were associated with adult plant resistance (APR).
Presented by Gens G.Froese, QUT
Wheat stripe rust (Puccinia striiformis f.sp. tritici) is a serious fungal pathogen affecting all major wheat-producing regions in Australia. Despite the ongoing development of resistant cultivars, this fungal disease remains a recurring and widespread problem to producers with potential yield losses of up to 80%. Early detection of infected plants is vital to enable timely treatment and prevent local disease outbreaks. However, to efficiently target crop monitoring resources, better guidance about the spatial distribution of risk is needed. We developed a risk model describing the potential for stripe rust outbreaks based on the disease’s infectious cycle. The model integrated important risk factors such as wind dispersal from infested fields, cultivar resistance and climatic conditions favouring rust infection and sporulation. Spatially-explicit predictions of outbreak risk were derived for wheat growing regions in mainland Australia. Research outputs can be used to guide the timing and spatial prioritization of on-farm crop monitoring decisions.
Presenterd by Denis M. Persley, DAFQ
In March 2016, a disease causing pod distortion, discolouration and leaf mottling in fresh market beans (Phaseolus vulgaris) occurred in the Fassifern area of south-east Queensland. Disease incidence in crops which are harvested nine to ten weeks after planting was frequently 60% to 100%, resulting in losses approaching $400,000 over a period of only two months. In April 2016, samples of soybean (Glycine max) cv. Zam-1 displaying virus-like symptoms of distorted leaves and mottling were collected from a crop near Gatton, approximately 50 Km from the infected bean crops. Disease incidence in this crop was 5-10%.
Increased carbon-dioxide affects crown rot incidence, severity and pathogen colonisation in wheat reducing potential grain yield.
Presented by Paul Melloy, Uni QLD
Plant pathogens and the diseases they cause are estimated to cause a 10 – 16% decrease in crop yield worldwide, with an additional 6 – 12% loss attributed to post-harvest spoilage. However, changes in the global climate as a consequence of rising atmospheric carbon-dioxide (CO2) are expected to further impact these losses. Crown rot (CR) of wheat has provided an excellent model to study the effects of elevated CO2 (eCO2) on disease incidence, severity, pathogen colonisation and the subsequent effect on grain yield. The effect of eCO2 on the CR pathogen, Fusarium pseudograminearum was assessed in controlled environment facilities (CEF), glasshouse experiments and at the Australian Grains Free-Air CO2 Enrichment (AGFACE) field experiment near Horsham, Victoria. The influence of CO2 on crown rot development was shown to be dependent on a number of factors.
Emerging Pests and Diseases
Presented by Ruth Dill-Macky Minnesota Uni, USA.
Bacterial leaf streak of wheat, caused by Xanthomonas translucens pv. undulosa (Xtu), has become prevalent in Minnesota, South Dakota, and North Dakota over the past eight years. Bacterial leaf streak is currently considered the second most important disease of wheat in Minnesota. Managing bacterial leaf streak is difficult due to the lack of resistant cultivars and other effective tools, especially as fungicides are ineffective against this bacterial pathogen. Over the past eight years we have demonstrated the economic importance of bacterial leaf streak; obtained useful data on the responses of regionally adapted varieties and elite germplasm to Xtu; refined techniques to establish bacterial leaf streak in inoculated field nurseries; and established a regional collaborative nursery to screen elite and released germplasm for response to Xtu.
Presented by Belinda E. Stummer, CSIRO
Strategies to effectively manage wheat crown rot, primarily caused by Fusarium pseudograminearum, are limited. Inoculation with Trichoderma strains, shown to suppress soil-borne fungal and oomycete diseases of cereals, offer potential to enhance disease management. Wheat crown rot suppressive assays were conducted in cereal cropping soils to assess rhizosphere competence and efficacies of Trichoderma inoculants in the presence of natural soil-borne microbial communities. F. pseudograminearum and Trichoderma colonisation were assessed in rhizosphere soil (RS), crown shoots (CS), crown roots (CR), primary roots (PR) by species-specific qPCR at 84 days post-emergence (grain fill).
Presented by Sharyn Taylor, PHA
Over the last decade, governments and plant industries in Australia have been responding to the detection of several significant plant pests and diseases. These incursions have had impacts on communities, production, domestic trade and the environment and include Myrtle rust, Red imported fire ant, Tomato potato psyllid, Russian wheat aphid, Banana freckle, Panama disease TR4, Chestnut blight, Giant pine scale, Khapra beetle, Varroa mite and Asian honey bee. In 2016 alone, Australia recorded 42 new detections of pests and diseases and, while not all were significant, this figure demonstrates the continual pressure of new threats.
Australia’s Grains Farm Biosecurity Program – a national initiative in plant biosecurity awareness, education and training
Presented by Rachel Taylor-Hukins, NSW DPI
Sound biosecurity systems contribute to achieving resilient and sustainable agricultural and environmental systems, reducing the threat of introducing unwanted pests and diseases. Within Australia, the Grains Farm Biosecurity Program (GFBP) is a national initiative to assist in the development and implementation of improved biosecurity practice within Australia’s grain industry. Initiated in 2007, the extension focused program contributes to the grain industry’s risk mitigation activities, supports continued market access and promotes a partnership approach involving governments, industry and community.
Presented by Barbara H. Hall, SARDI
The National Plant Biosecurity Diagnostic Strategy (NPBDS), released in 2012, fulfills an essential component of the overarching National Plant Biosecurity Strategy. It publishes the agreed recommendations and actions necessary to ensure Australia has the people, infrastructure, diagnostic standards and tools to provide delivery of plant biosecurity diagnostic services. The Subcommittee on Plant Health Diagnostics (SPHD) aims to sustain and improve the quality and reliability of plant pest diagnostics in Australia, and is integral to achieving the recommendations in the NPBDS.
Managing biosecurity risk of exotic insect pest and pathogen incursions in wheat through pre-emptive breeding
Presented by Livinus Emibiri, NSW DPI
The recent discovery of Russian wheat aphid demonstrates the potential impact of pest incursions into Australia, and the absence of resistant cultivars that can be easily deployed. Further, there is no incentive for wheat breeding companies to develop resistant varieties due to the cost burden and low return on investment. Here, we report on research undertaken at ICARDA and CIMMYT, which indicates that the Australian wheat industry is very vulnerable to damage from certain pests, especially Hessian fly (zero resistance), Karnal bunt (3.6% resistance) and Sunn pest (1.5% resistance). Although these pests and pathogen are not currently present in Australia, much of the Australian cereal cropping regions offer an acceptable climate for the pests to establish. The purpose of our research is to reduce the risk of potential future economic loss to wheat growers due to incursion by providing wheat breeders with molecular markers and parental genetic stocks that carry genes for resistance to Karnal bunt, Hessian fly and Sunn pest. Using conventional breeding methods, elite Australian breeding lines have been developed that combine resistance to the exotic pests and fungal disease with good agronomic qualities. In addition, data is being generated to determine whether any deleterious traits have transferred from landraces along with the resistance genes.
Pest and Pathogen Surveillance
Presented by Jenny Davidson, SARDI
New technology is rapidly developing and creating opportunities for surveillance of airborne pest and disease threats. In response the Grains Research and Development Corporation initiated the CRC Plant Biosecurity Project 2014 ‘New tools for field grains surveillance and diagnostics of high priority exotic pests’ lead by SARDI. This project has developed and evaluated ‘Smart’ Spore and Insect Trapping systems which collect samples referenced to parameters including GPS and climate data (temp, wind direction, RH) and include wireless data transmission of digital images or improved design for downstream diagnostics such as molecular assays of pest targets. These approaches demonstrate the benefits of partnering with engineering to include automation and innovation; in this instance resulting in trapping systems with smart capabilities and capacity for high sampling frequencies. Prototypes currently under evaluation at SARDI include the Mobile Jet Spore Sampler, Sensor Moth Trap and Insect Suction Trap resulting from collaboration with engineers at USQ as well as strong linkages to Burkard Manufacturing Co. (Stuart Wili) and Rothamsted Research (Prof Jon West) in the United Kingdom.
Comparison of rooftop and field-based air samplers for early detection and population monitoring of plant pathogens
Presented by Jon S. West, Rothamsted Research UK
Air sampling allows us to monitor air-dispersed plant pathogens using a range of downstream diagnostic methods including DNA based diagnostic assays and sequencing. Recent work to investigate the timing of spore release of pathogens and to evaluate potential automated spore traps with wireless reporting has compared sampler location, whether on a rooftop or at ground level in production fields. Examples of several pathogens, including Sclerotinia sclerotiorum, Phytophthora infestans, smut fungi and rusts have been compared. Generally, rooftop spore trap samples contain greater diversity than samples from ground-based locations, reflecting greater mixing of air incorporating spores from a wider range of micro-environments in the region for the rooftop sites. Pathogens known to be present in crops and found in air samples taken above the field are also found at rooftop sites, typically with numbers reduced by dilution to between 1/10th to 1/100th of what was found in the production field. However, at early stages of epidemics, spores were frequently detected albeit in low concentrations by rooftop samplers compared to samplers in production fields that did not detect any target spores. The use of high volume spore samplers will be discussed as a way to enhance the sensitivity of rooftop sample location.