Cabbage Integrated Pest Management : An Ecological Guide.

Major Agronomic Practices3.8.4 MulchingMulching means keeping the soil surface covered with non-transparent material. Mulching reduces weedgermination and it will keep the soil cool and moist because the sun cannot shine directly on the soil.Organic mulch can provide shelter for predators such as ground beetles and spiders. Mulching can bedone both on the nursery after sowing (also to prevent birds from eating the seed) and after transplantingin the main field. Mulch on the nursery usually needs to be removed once the first seedlings havegerminated.Mulch can be a layer of organic material, for example rice straw or a layer of green leaves, saw dust oreven pulled out weeds without seed. Mulching can also be done with non-transparent plastic sheets.This is however, quite expensive! Sheets should be non-transparent because that prevents germination ofweeds. Seed usually need light for germination. A disadvantage of using black (or non-transparent)plastic sheets can be that the soil temperature is increased. This type of mulch should be removed whentemperature becomes excessive (over 32 o C) under the covers.In cool areas, a rise in soil temperature may be an advantage as it increases root growth and may induceearly yields, and in some cases increase total yields.Mulching may have a role in reducing pests and diseases. Plastic mulches with aluminium film havebeen shown to reduce aphid attacks. The shiny aluminium reflects light and deters aphids. Silver coloredplastic has the same effect, white and yellow plastics to a lesser extend. This is particularly useful whereaphids transmit virus diseases, such as in tomato, or chili. It is probably not economical for use incabbage.Diseases that spread with soil particles with splashing water from rain, such as black rot (Xanthomonascampestris), and leaf spot (Alternaria brassicae) cannot spread so easily when the soil surface is coveredwith a mulch.See also section 3.5.3.4 on organic mulch.Related exercises from CABI Bioscience/FAO manual:2-C.1. Farmers’ field preparations and problems2-C.2. Plant spacing2-C.7. Mulching of plant beds: organic and inorganic mulchesCabbage Ecological Guide - 200044