Impact of root diseases on pulse crops in Northern and Southern regions

New research will be undertaken across the Southern and Northern regions to determine the causes of root disease in pulse crops and to measure the extent of impacts on root health and on grain yield and biomass reduction. The project will run from 2022-2025 and includes researchers from the South Australian Research and Development Institute (SARDI), Agriculture Victoria Research (AVR), New South Wales Department of Primary Industries (NSWDPI) and Queensland Department of Agriculture and Fisheries (QDAF). The research team will conduct field trials evaluating pathogenicity and associated yield losses of important pulses pathogens, while commercial crops will be monitored to improve the understanding of the causes of disease and survival of pathogen inoculum.   The area sown to high value pulse crops including chickpea, lentil, faba bean and mung bean has steadily increased over several decades, while lupin remains an important rotational crop on acid soils, particularly in parts of South Australia and New South Wales. Historically viewed as a break crop to reduce weed and disease issues in cereal crops, pulses are now often highly profitable in their own right and grown in frequent rotation. International experience suggests that as cropping frequency increases, soilborne diseases become important in pulses, just as in cereal crops. Reports of poor performance indicate that root diseases are common in Australian pulse crops and may be a significant limitation to production. To identify possible causes of root disease in Australian pulse crops, a survey was undertaken as part of South Australian Grains Industry Trust (SAGIT project S218) and Grains Research and Development Corporation (GRDC project DJP1907-002RMX) investments from 2018-2020. The survey combined traditional tools such as visual assessment and laboratory isolation with two molecular approaches: Next Generation Sequencing and qPCR testing. The survey analysed over 850 samples, mainly from commercial growers, and identified a number of important pathogens that may be limiting pulse yields nationally. New tests were developed during this period to allow detection and quantification of pathogens in roots and mixed soil samples.  The current GRDC investment will build on the previous research and focus on key pathogen x crop systems. The research will be conducted primarily in the field and will aim to quantify the impacts of pathogens causing root disease in pulse crops, while also evaluating management strategies. From 2022, monitoring sites will be established in poor performing commercial pulse paddocks to: determine the cause of root disease; establish the relationship between molecular test results and root disease; assess the survival of root disease inoculum in soil; and measure the biomass and yield impact of root diseases in commercial crops. Monitoring sites in SA and Victoria will target faba bean and lentil, while chickpea, faba bean, mung bean and lupin crops will be targeted for monitoring in QLD and NSW. The causal pathogens will be isolated from diseased plant roots for use in field trials.    Yield losses from phanomyces euteiches, widely considered to be the most devastating root pathogen of lentil and field pea internationally and known to affect faba bean in Australia, will be measured in trials in northern NSW and SA in 2023 and 2024. Isolates will be collected from SA and NSW to compare pathogenicity. The resistance of current faba bean cultivars to Aphanomyces euteiches will be evaluated to provide growers with a potential management option where this pathogen is a problem. In 2023 and 2024 field trials will be conducted in SA, Victoria and NSW to evaluate the pathogenicity of a broad range of fungi and oomycetes, including Fusarium spp., Phytophthora spp., Phoma spp. and Pythium spp. Replicated single row trials will be used to rank the most damaging root pathogens of chickpea, faba bean and lupin in the Northern Region, and lentil and faba bean in the Southern Region. Plots will be assessed for root health, biomass and grain yield. The most damaging pathogens will progress to evaluation in larger plot field trials to confirm yield losses, and may include mixed species pathogen complexes, which are common.