No abstract

Much research has been done on biological disinfestation of soil with grass and other fresh organic materials to suppress persistent diseases like Verticillium dahliae and nematode populations in the soil. After covering the soil with airtight plastic and creating an anaerobic environment, natural processes that will have a disinfesting effect on the soil are stimulated by the organic material. Practical conditions may vary enormously and so it seems that soil disinfestation with grass or other fresh materials is unpredictable. Growers find this method complicated and labor intensive. In particular, growers of horticultural crops are not enthusiastic about biological soil disinfestation with grass. As an alternative for fresh materials, organic fermentation products have been tested.Application is easier and effects occur faster than with fresh organic materials. Therefore, this method offers a chance to explore the possibilities for broad application in horticulture as an alternative for soil disinfestation with steam. Product H7022 (ThatchTec B.V., Wageningen, The Netherlands), consists of organic by-products from the food processing industry, and resulted in a 100% reduction of nematodes and Verticillium dahliae. The major drawback to this method is the treatment time of at least two weeks, which is too long for most greenhouse growers, as the costs of a two week time gap in production are too high, making it difficult to adapt to a greenhouse system. New research on organic fermentation of the soil is necessary to determine which processes cause soil disinfestation, during what time period this method causes an effect, and whether or not this method is suitable for use in soil-bound horticulture.