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Increasing crop production through biological control of soil-borne root diseases

Overview of Project

The aim of the project was to control various fungal root diseases that affect many crop plants by selecting and evaluating a range of Australian and Chinese soil microbes for use as biological control agents against the fungi responsible for disease. This would reduce the need for chemical fungicides or for cultivation treatments that could lead to soil erosion. The ultimate aim was to develop effective and reliable treatments that farmers could use to control important soil-borne root diseases of the target crops.

Soil-borne root diseases can often greatly reduce agricultural and horticultural productivity. ‘Take-all’ and Rhizoctonia diseases of wheat, along with ‘damping-off’ in vegetables and Verticillium wilt of cotton are of considerable economic importance in China and Australia. In southern Australia alone the loss of wheat to take-all disease is about $100 million per year. In China, where it is a problem under irrigated wheat, the value of lost production is estimated at $250 million per year. Cotton, one of Australia’s largest export earners, can also be severely affected, with the only solution being to replant the entire crop at considerable effort and expense.

Root diseases can be controlled somewhat by cultivation, but heavy cultivation may increase soil erosion. Conservation tillage regimes, introduced to reduce soil erosion by minimising the tilling of the soil, may benefit soil structure and water use but can actually increase root diseases. There are no signs that this has happened yet in northern China, but experience in America and Australia suggests that it is likely.

Biological controls were sought in the interests of safer and cleaner methods of disease control. A search for solutions that did not rely heavily on fungicides led to the introduction of beneficial soil fungi and bacteria that compete successfully with the pathogenic fungi, leading to disease control and increased root growth.

Commercial use of some of these microbes is now well established in Australia, USA, Europe and China. However, a major problem has been the lack of consistency in the response of plants to the application of these control agents, probably because of differences in the physical and chemical characteristics of soils. The project helped address this problem. It followed on from a one-year ACIAR project that tested the ability of selected soil bacteria and fungi to control take-all and Rhizoctonia of wheat under glasshouse conditions.

Key Outcomes of Project

The project showed that grain yield increases of 10 per cent were possible, with the best agents clearly outperforming fungicide. Good progress was made in understanding mechanisms of plant responses to biocontrol agents, and applying modern molecular techniques to these issues. One agent from Australia (Tk7a), with formulation from China, looked sufficiently promising to be considered for registration in both countries, and a commercialisation agreement between CAU and CSIRO was signed in November 1999.

Trichoderma Tk7a was produced under licence in China by the MinFeng company in 1999 and 2000. Factory procedures for producing the product were developed. Beyond 2000 the MinFeng company stopped producing biological control products, but new possibilities for sublicensed production in China progressed and formed the basis of an AusIndustry commercial development project. Field tests in Australia between 1999 and 2002 were done using the Trichoderma product formulated according to Chinese-developed methods. Potential for further commercial development in Australia was a part of the AusIndustry project.

However, despite the extensive field testing and the enthusiasm for commercialisation in China, the responses to biocontrol agents in wheat and cotton were patchy, sometimes because root disease did not develop in the control plots. The agents seemed to be as good as the fungicide seed dressing Baytan, and probably would be a lower cost option, but newer fungicides may be more effective. Progress was made in formulation of the agents for delivery to seed, overcoming what had earlier seemed to be an obstacle to its introduction. Testing on vegetables did not reach the field; effects seemed related to growth promotion as well as to disease control.

The ultimate aim of the project had been to develop a product for farmers to use, though this had not been expected within the life of this project. The fact that this stage was reached demonstrated a positive future for biological control and was a measure of the strength of the cooperation and the high level of skills available to the project.

An application was drafted for submission to AusAID China Program for funds to run a pilot agricultural extension project that covered general strategies for control of soil-borne diseases in western China (focus on Inner Mongolia). Biological control would be included as one strategy for control of disease. The production of appropriate, end-user-friendly extension materials was included as an integral part of this project. If successful this could be extended to other areas of China, particularly western provinces."

Project Dates

01 Jan 1997 - 30 Jun 2001

Partners

China Agricultural University - China
Chinese Academy of Agricultural Sciences - China
Zhejiang Agricultural University - China
Australian Cotton Research Institute - Australia
CSIRO Land and Water - Australia

Leaders

Dr Maarten Ryder

Email

ryderresearch@chariot.net.au

Phone

0409 696 360

Website
Launch Website