Cabbage Integrated Pest Management : An Ecological Guide.

Major Agronomic PracticesRelated exercises from CABI Bioscience/FAO manual:2-C.5. Fertilizing experiments2-C.6. Use of foliar fertilizers2-A.6. Composting2-A.7. Use of compost3.6 Planting time and pest occurrenceThe type and number of pest and diseases can vary in different times during the year. During the dryseason for example, there will usually be less problems with diseases. Knowing when a pest or diseaseis most severe can offer an opportunity to plant the crop during the time that pests and disease are notpresent in large numbers or just before that time. That gives the plant the opportunity to be well establishedin the field before an attack by an insect or a disease occurs.Planting time and insects, an example from Lao PDR:During the cool season in Lao PDR, October to January, there are no major problemswith pests or diseases of cabbage. From February onwards, the temperature rises and pests suchas diamondback moth (Plutella xylostella) and webworm (Hellula undalis) become a problem.Related exercises from CABI Bioscience/FAO manual:2-A.12. Weather conditions and planting time3.7 Nursery management3.7.1 Soil sterilizationThere are several ways of sterilizing soil, both as a preventive measure against soil-borne diseases (suchas damping-off) and as a method to control soil-borne diseases already present. A number of commonpractices is shortly described below.To see if any of these soil sterilization methods work in your field, set up a study to compare this methodagainst the common practice!3.7.1.1 Burning organic material on the soilA common method of soil sterilization is heating up the soil. The high temperature will cause the deathof many micro-organisms, including pathogens in the top soil and insect pest with soil-dwelling stages,such as cutworms. In Bangladesh, Nepal and India, for example, soil sterilization is commonly practicedby burning straw, or dry grass, leaves or waste material on the nursery beds before sowing. It should benoted that straw burns very shortly and the heat does not penetrate deep enough into the soil. This mayresult in only a very thin top layer of the soil being sterilized. A substantial amount of slow-burning buthigh-temperature output material would be required on the soil, e.g. wood rather than grass (Bridge,1996). Rice husk is preferred to straw because it burns slower and the heat penetrates deeper into thesoil, resulting in better sterilization.In Bangladesh, Choudhury and Hoque (1982) demonstrated that by burning a 5-cm thick layer of ricehusks (burnt in 90 min) and a 5-cm thick layer of sawdust (burnt in 60 min) on the surface of vegetableCabbage Ecological Guide - 200036