Cabbage Integrated Pest Management : An Ecological Guide.

Major Agronomic Practicesthis layer, the effect disappeared. It is planned to test the method on larger scale production fields.Similar studies showed that biological soil sterilization was effective against the fungi Fusarium oxysporum,Rhizoctonia solani and R. tuliparum, Verticillium dahliae, Sclerotinia sclerotiorum and different nematodespecies (Meloidogyne and Pratyenchus).This soil sterilization method can be combined with solarization (see section 3.7.1.2). Under the Dutchtemperate conditions (with low amount of sunshine), the plastic used was non-transparent to preventweeds from germinating under the plastic and produce oxygen, thus reducing the sterilization effect.However, when using transparent plastic under tropical conditions, the expectation is that the soiltemperature rises enough to kill weed seeds. When incorporating organic matter into the soil beforeplacing the plastic sheets, three effects may be obtained:lllsoil sterilization by fermentation processes caused by degradation of organic material by microorganismsunder anaerobic (no oxygen available) conditions,soil sterilization by rise of soil temperature due to sunshine and plastic sheets,addition of organic material through the green manure crop to improve soil structure and soil fertilization.(Blok, PAGV Jaarverslag 1998; pers. comm. Dr. W. Blok, Wageningen Agr.Univ., 1999).3.7.1.6 Boiled waterAlthough not “scientifically proven” the use of boiling water for soil sterilization may be an option for soilsterilization. A farmer from Bangladesh used this method: he boiled water and poured it one to threetimes over the nursery soil to kill pathogens and possibly insects and/or nematodes in the seedbed. Helet the soil drain and cool down before sowing the seed (pers.comm. Chittagong farmer Bangladesh).It would however be advisable to set up an experiment (possibly with pot trials) to test if this methodwould be appropriate for your area.“ ’’To see if any of these soil sterilization methods work in your field,set up a study to compare the method against the common practice!3.7.2 SowingCabbage can be sown directly in the field or sown in a nursery and transplanted later. Usually, cabbageis sown in a nursery. This nursery should ideally be located at a sunny place where the soil is not toowet. High humidity may provoke diseases like damping-off which can destroy seedlings in a very shorttime. If possible, the nursery should be sited on land which has not grown cruciferous crops like cabbage,cauliflower, or broccoli for 3 years or more. This is a prevention for the occurrence of (soil-borne) diseases.3.7.2.1 Flat field and raised seedbedsProper drainage and aeration are necessary to prevent soil-borne diseases like damping-off. A goodoption is to prepare raised seedbeds which will dry more quickly than flat-field plantings.Compost can be mixed in the seedbeds to get a fine soil structure with sufficient nutrients. Compost mayalso help prevent damping-off. See section 3.5.3.1. Make sure the seedbeds are properly leveled. Digtrenches between the seedbeds to facilitate drainage of the nursery.39 Cabbage Ecological Guide - 2000