Biofumigation refers to the use of plants in the Brassica family to produce natural chemicals that are toxic and behave like some pesticides used to fumigate soil. The aim is to achieve a more generally acceptable and biologically-based method of suppressing pests and diseases in soil.

Soil-borne pest and diseases are a major problem for many of Australia’s horticultural producers, decreasing yields, and affecting quality. Some industries can afford to use expensive synesthetic fumigants and pesticides, but many cannot. Most producers would prefer to avoid or at least limit their use of such chemicals.

Rotation crops of various kinds are often used to break the life cycle of pests and diseases, but the purpose of this research project was to achieve greater effects by using brassicas and treating them in such a way that maximised the release of the fumigant-like chemicals. It also aimed to find simple methods for producers to grow brassicas without specialist machinery.

The research found that dense stands of rapes and mustards could be produced after sowing seeds onto well prepared land using simple equipment. The most significant findings centred on achieving maximum release of the fumigated chemicals from the plants, where amounts over ten times greater than had been previously obtained were achieved.

To achieve the maximum chemical release it is most important to thoroughly pulversise the plant material using a mulching machine fitted with club blades. Cutting blades are inadequate as they only chop the plants into fragments. It is then vital to water the mulched plant material thoroughly to assist the reactions that produce the chemicals, and carries them into the soil.

The results of this research project give the basic knowledge that will assist producers in making decisions about the various alternatives for managing soil pests and diseased and implementing them in their various production systems.