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Increased aggressiveness of Fusarium pseudograminearum isolates causing crown rot disease on wheat in Western Australia

Mohammed Khudhair: The university of Queensland/ CSIRO Agriculture and Food

<div><strong>Abstract</strong></p> <p>Fusarium crown rot (FCR) caused by the fungal pathogen <em>Fusarium </em><em>pseudograminearum</em> (<em>Fp</em>) is a chronic and serious disease of wheat and barley in many countries, including Australia, as it causes high yield losses and low grain quality. The incidence and severity of FCR in most wheat growing regions of Australia, and particularly in Western Australia (WA), have been increasing in the last decade. To investigate if <em>Fp</em> isolates are becoming more aggressive, a total of 103 <em>Fp</em> isolates collected from two intensively sampled wheat fields in WA (Tammin and Karlgarin) in 2008 and 2015 were genetically analyzed. The aggressiveness of the isolates was also tested on seedlings of the susceptible wheat cultivar Mace using a paper-towel bioassay. Overall, the results revealed significant differences between the two sampling years within the two surveyed paddocks with the aggressiveness of isolates sampled in 2015 being significantly (<em>P<</em>0.0001<em>) </em>higher than that of the 2008 isolates. This indicates a shift towards more aggressive isolates occurring within pathogen populations in WA. However, there was no significant (<em>P</em><0.5) difference in the aggressiveness of isolates from between the two paddocks sampled at either year. Increased aggressiveness of <em>Fp</em> isolates collected from the same locations in different years correlates with the recent increases of FCR incidence and severity in WA and this may have implications in managing this important wheat and barley disease.</div>