BIOLOGICAL-CONTROL OF SOIL-BORNE DISEASES - SOME PRESENT PROBLEMS AND DIFFERENT APPROACHES

Despite much recent interest in the biological control of soil-borne plant diseases it is difficult to find examples of commercial exploitation. This may be because inappropriate laboratory screening systems are used: screens must select for organisms adapted to the environment in which they will operate. Assessment of screening procedures is difficult on published information, but it seems that insufficient organisms are screened and the screens may sometimes not be as well targeted as might be hoped. An alternative approach, which has no commercial basis, is to develop traditional rotations, green manuring and organic amendment systems so that the microbiology is understood and can be manipulated, with or without added inocula, to achieve biocontrol. Development of added inocula is scientifically interesting and commercially fundable, but seems to have had only limited success at present. Traditional approaches are not 'glamorous' science, are not commercially viable because there is no product, and have received little funding, but are known to be effective in many instances although the microbiological reasons for this may not be understood.