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THE IMPACT OF SUMMER RAINFALL EVENTS ON R.SOLANI INOCULUM
BUILD-UP AND IN-CROP EXPRESSION
B.S. Congdon A in coordination with R. Lawes B and M. Renton A
A The University of Western Australia, Crawley Campus, congdb01@student.uwa.edu.au
B CSIRO, Shenton Park
ABSTRACT. Predicting the severity of soil borne diseases on cereal crops is integral in managing risk in rain-fed cropping
systems. Prediction based on knowledge of pre-sowing environmental and edaphic conditions is the only tangible way of
accuratelypredicting disease expression. In this experiment, soil infected with Rhizoctonia solani AG-8 was incubated over 6
weeks under 4 different watering frequencies to emulate the rapid and sporadic wet-dry rainfall patterns often exhibited in
summer in Western Australian cropping systems. Pre incubation inoculum levels were coupled with sowing bioassays and
plant analysis/post sowing inoculum levels to determine the impact of summer rainfall on the inoculum survival and
suppression in the soil. Plant growth was also monitored to evaluate whether the interaction between inoculum and summer
rainfalls affect the subsequent crop. Cereal residue was added to half the pots, further altering the evaporative demand,
wetting and drying profiles of the soil. Results from this experiment can then be used for further research in eliminating the
information gap in linking the environment to soil-borne disease expression allowing for better prediction of disease severity
and thus on-farm risk management as the grower decides on whether growing a wheat crop is too risky or not.
7th Australasian Soilborne Diseases Symposium 48