Rhizoctonia bare patch disease inoculum build-up in different cereal crops and varieties

Gupta, V.V.S.R.¹, Alan McKay² and Nigel Wilhelm²

¹CSIRO Agriculture Waite campus; ²SARDI Waite campus

Research Team: Bill Davoren¹, Stasia Kroker¹, Marcus Hicks¹

Funding: DAS00125, MSF00003

Key Words: rhizoctonia, rhizo, root disease, cereals, inoculum build up

Key Messages

• A significant variation in the rhizoctonia inoculum build-up exists between cereal crops wheat, barley, Triticale and Cereal Rye and their varieties. Inoculum build-up was generally higher in the barley varieties compared to that in other crops. Results are in general agreement with observations in other experiments in the Mallee and on calcareous soils in Eyre Peninsula.
• Differences in inoculum levels carried through summer and seen at sowing in 2016 suggest that farmers may select between cereal crops and their varieties to limit inoculum building during cereal phase. However, non-cereal break crops are the best option to reduce the pathogen inoculum in a cropping system.
• Soil physical (compaction), chemical (organic C and nutrients) and biological (activity and composition) characteristics and seasonal (temperature and rainfall) factors can influence the growth of R. solani AG8 fungi and the severity of rhizoctonia disease.

Why was the trial done?

An effective control of rhizoctonia disease caused by R. solani AG8 impacts requires an integrated management program over multiple years to (i) reduce the pathogen inoculum levels and (ii) control infection and impacts on plant growth. Non-cereal crops in rotation have been shown to reduce the pathogen inoculum levels, however, reduction of inoculum build-up under cereal crops/varieties is considered to be a useful trait in the cereal phase dominated cropping systems commonly followed in the rainfed regions of Southern and Western Australia. The aim of this work was to determine the variation in the build-up of R. solani AG8 inoculum between cereal crops wheat, barley, triticale and cereal rye and varieties in a cropping system.

How was the trial done?

In 2015, a field experiment was conducted at Karoonda, SA with different varieties of Wheat (EMU Rock, Harper, Mace, Scout, Yitpi), Barley (Buloke, Skipper, Schooner, Fathom, Scope, Commander), Cereal rye (SA Commercial, Bevy) and Triticale (Fusion, Bogong) to determine the pattern of rhizoctonia inoculum build-up within the crop. After the harvest of 2015 crops, plots were maintained during the summer with chemical weed control and in 2016 Scope barley was sown (@ 70kg/ha) on June 6^th on all plots using a one pass sowing equipment with knife points. Root disease incidence at 8 weeks after sowing, plant growth and grain yield were monitored.

Acknowledgements

We thank the Loller family, Karoonda for allowing to conduct the rhizoctonia trials on their farm during 2015 and 2016 seasons; Willie Shoobridge, Bill Davoren, Stasia Kroker, Paul Adkins and Marcus Hicks for field and laboratory work and funds provided through GRDC projects DAS00125, MSF00003.