Tackling Rhizoctonia in low and medium rainfall zones
Project name
Project name: Epidemiology and management of Rhizoctonia in low and medium rainfall zones
GRDC Code
DAW2206-006RTX
Insights and economic impact
With support from the Grains Research and Development Corporation, a team of researchers from the Department of Primary Industries and Regional Development, University of Adelaide, and CSIRO have come together on a 3-year project to address knowledge gaps in ways to reduce the impact of rhizoctonia (Rhizoctonia solani) during wheat and barley production in the lower rainfall zone (LRZ).
Rhizoctonia solani is a species of fungus which causes a brown rot of stems, impairing plant growth, resulting in significant yield losses.
It is a disease estimated to potentially reduce WA state-wide cereal yields by up to 5 per cent annually, costing West Australian growers up to $27 million in wheat and barley in lost revenue.
There are currently no commercially available resistant cultivars for it.
Research has shown in the absence of resistant cultivars, the disease can be managed by crop rotations and fungicide applications.
However, in the LRZ, some of the unique properties of calcareous soils (soils high in calcium carbonate, resulting in poor crop establishment and low grain yields compared to less hostile soils) may render current management approaches less effective.
For this reason, these practices have not been widely adopted by growers in areas throughout WA.
This project commenced in Northam in 2021 with a field trial at Muresk and will continue until 2025.
Over this period the research aims to deliver the following outputs:
- Innovative and effective management strategies for rhizoctonia;
- New knowledge on the epidemiology of the disease, including seasonal triggers driving increased disease expression and factors influencing disease expression interactions;
- Establish the economic/disease impact of Rhizoctonia in the LRZ and medium rainfall zone (MRZ) of the southern and western regions;
- Deliver engagement activities that build grower knowledge and the confidence to implement best management practices for rhizoctonia, to minimise its impacts on production.
The project is using soil amelioration treatments including inversion, deep ripping, and a control treatment combined with barley and canola rotations.
Researchers discovered the site which had a low-medium background of rhizoctonia and this did not increase over 2 years.
The team also found rhizoctonia DNA in the inversion treatment remained low compared to the other two soil amelioration treatments, particularly at 0-10cm.
Soil amelioration had little effect on the presence of rhizoctonia at depths beyond 20cm.
When plots were planted with canola there were reduced rhizoctonia DNA in all treatments and was generally low at the end of the experiment.
In the high rainfall zone (HRZ), mechanical soil amelioration treatments were applied to a sandy loam site with low-medium levels of rhizoctonia DNA on canola stubble from 2020.
At the beginning of the 2021 season, DNA levels combined in barley and canola crops reduced by around 10-centimetres after the inversion treatment, compared to the no tillage control and deep ripping.
At the end of 2022, there was a significant two-way interaction between tillage or crop with a depth of <0.002.
For mechanical soil amelioration with depth, the inversion treatment had significantly lower rhizoctonia levels in both the 0-10 and 10-20cm depths compared to the nil and at 0-10 this was also significantly lower than the deep rip.
DPIRD Research Scientist Daniel Huberli said there were no treatment differences beyond 20cm.
“However, for crop by depth interaction, rhizoctonia DNA levels were significantly lower in canola compared to barley in both 0-10 and 10-20cm depths, while beyond 20cm depths there were no significant differences between the two crops.
As the levels have not increased to high levels, the trial will be discontinued in 2023.” He said.
Canola’s role in supressing rhizoctonia
Researchers discovered a reduction in rhizoctonia DNA in paddocks sown with canola from autumn to spring, prompting suggestions that canola supresses the fungus from growing.
A finding from the study found adding lime helped barley plants as they were healthier and higher yielding.
So, planting canola between barley crops and taking care of the soil through amelioration practices can help farmers have better crops and yield.
Contact
Daniel Huberli
DPIRD research scientist
E: Daniel.huberli@dpird.wa.gov.au
P: (08) 9368 3836