Stubble trouble! Moisture, pathogen fitness and cereal type drive colonisation of cereal stubble by three fungal pathogens

Abstract

Stubble-borne cereal diseases are a major constraint to production in Australia, with associated costs rising as a result of increased adoption of conservation agriculture systems. The fungal pathogens that cause these diseases can saprotrophically colonise retained cereal residues, which may further increase inoculum levels post-harvest. Hence, saprotrophic colonisation by the stubble-borne fungal pathogens Fusarium pseudograminearum, Pyrenophora tritici-repentis and Bipolaris sorokiniana were compared under a range of moisture conditions for stubble of six cereal varieties (two bread wheat, two barley, one durum wheat and one oat). Sterile cereal stubble was inoculated separately with two isolates of each pathogen and placed, standing, under constant relative humidity conditions (90, 92.5, 95, 97.5 and 100%) for 7 days at 25 °C. Stubble was then cultured in increments of 1 cm to determine the percentage colonisation height of each tiller. Fusarium pseudograminearum colonised farther within tillers, leaving a greater proportion of the standing stubble colonised compared with B. sorokiniana and P. tritici-repentis, suggesting F. pseudograminearum has higher saprotrophic fitness. Saprotrophic colonisation also increased with increasing relative humidity for all pathogens and varied by cereal type. Disease management strategies, such as reduced cereal harvest height, may limit saprotrophic colonisation and improve stubble-borne disease management in conservation agriculture systems.

Interactions of Fusarium Crown Rot of Wheat with Nitrogen

“…Three isolates of Fp were prepared following methods outlined in [ 19 ]. Agar cubes (2 mm 3 ) of each isolate were cut from the margin of colonies and transferred onto separate Petri dishes that contained ¼ strength Potato Dextrose Agar (PDA) + novobiocin (10 g PDA, 15 g technical agar, plus 0.1 g novobiocin/L water).…”

A review on common root rot of wheat and barley in Australia

“…As B. sorokiniana survives in stubble and soil for up to 10 years, stubble management practices have been the focus of CRR management. A recent study reported that moist conditions increased B. sorokiniana development within postharvest cereal stubble, and inoculum density may increase if wet weather occurs after harvest (Petronaitis et al, 2020). A reduction of cereal stubble biomass may limit the proliferation of B. sorokiniana after harvest, leading to less inoculum carried forward to the following season (Petronaitis et al, 2020).…”

“…A recent study reported that moist conditions increased B. sorokiniana development within postharvest cereal stubble, and inoculum density may increase if wet weather occurs after harvest (Petronaitis et al, 2020). A reduction of cereal stubble biomass may limit the proliferation of B. sorokiniana after harvest, leading to less inoculum carried forward to the following season (Petronaitis et al, 2020). Harvesting at low heights or cutting for hay are possible options, but field validation is required (Petronaitis et al, 2020).…”

“…A recent study reported that moist conditions increased B . sorokiniana development within postharvest cereal stubble, and inoculum density may increase if wet weather occurs after harvest (Petronaitis et al, 2020). A reduction of cereal stubble biomass may limit the proliferation of B .…”

“…A reduction of cereal stubble biomass may limit the proliferation of B . sorokiniana after harvest, leading to less inoculum carried forward to the following season (Petronaitis et al, 2020). Harvesting at low heights or cutting for hay are possible options, but field validation is required (Petronaitis et al, 2020).…”