SUSTAINABLE DISEASE MANAGEMENT IN LOW-RAINFALL CEREAL PRODUCTION SYSTEMS
SM NEATE and DK ROGET
CSIRO, Land and Water and Cooperative Research Centre for Soil and Land Management, PB No 2, Glen Osmond, SA 5064, Australia
Background and objectives
Low-cost systems of sustainable disease control have developed in low-rainfall cereal production systems in southern Australia because low yields (an average of 1.8 t/ha) and low returns (an average of less than $US 140/t) do not allow for high-value applications of pesticides, nutrients or amelioration treatments.
Materials and methods
Conventional cultivation consisted of three cultivations with 15 cm shares before sowing, reduced cultivation was one cultivation with 15 cm shares before sowing, and direct drilling was no cultivations prior to seeding and sowing with a 1 cm or less wide point.
Annual measurements of root disease, plant growth and yield were made.
Results and conclusions
Management of take-all and CCN is based on rotation with non-host crops or the use of volunteer legume-based pastures where grasses are chemically removed early in the season. Both diseases decline under fallowing and non-hosts, but fallowing is discouraged because of its detrimental effect on soil structure.
The management of CCN has been significantly improved by the development of resistant and tolerant cereal cultivars. These new cultivars have replaced the use of nematicides which were in common use during the 1980s. There is no useful resistance to rhizoctonia root rot or take-all diseases in the major cereals.
An area of major research effort is in soils suppressive to root diseases of cereals. After 8-10 years of stubble retention and cropping, both rhizoctonia bare patch and takeall declined in field plots to insignificant levels and have remained there since, despite fluctuating levels in the surrounding farmers' fields . Investigation of the soil revealed the development of microbiologically based disease suppression . Unique characteristics of this suppression are that it is not associated with