Cabbage Integrated Pest Management : An Ecological Guide.

Disease EcologyTrichoderma species are successfully used and multiplied in several countries in Asia, including Thailand,Philippines, Vietnam and Indonesia (FAO-ICP Progress report ’96 – ’99).Trichoderma sp. should be mixed into the soil a few days before (trans)planting.L A negative effect of Trichoderma has been reported on mushrooms. Trichodermacan negatively influence mushroom cultivation, possibly due to killing or inhibitingthe mushroom fungi. More research is needed to study these effects, but in themeantime it is advisable not to use Trichoderma close to a mushroom productionarea (Harman et al, 1998).Related exercises from CABI Bioscience/FAO manual:3.5. Beneficials among the pathogen groups7.11 What about fungicides...?Available fungicides and bactericides are often not effective enough to stop any of the major cabbagediseases, especially during prolonged periods of wet weather. Fungicides (if at all necessary) shouldalways be combined with structural management methods like crop rotation, sanitation, etc. (see section7.8).7.11.1 Chemical fungicidesThere are several ways of classifying fungicides. An often used classification is the following:· Preventive fungicides: those should be applied before the disease actually occurs. The fungicide willform a protective layer around the plant which prevents spores from germinating on the plant. Butagainst what diseases you should spray is often unclear and timing of fungicide application is verydifficult to predict. Also, when it rains, the fungicide will be washed off the leaves and there is noprotection anymore, just environmental pollution. There are products that can be added to the fungicidethat help it stick better to the plants, these are called stickers. Results in practice however vary.· Curative fungicides: products that you can spray when symptoms of a disease occur. Some of theseform a layer around the plant (contact products), others are uptaken by the plants and transportedthrough the veins to other plant parts (systemic products).Good toknow about fungicides:· There are few effective sprays against bacterial diseases!· There are no sprays against virus diseases! (usually insect vectors should be prevented fromentering the crop in areas where virus diseases are a problem).· Control of soil-borne diseases with fungicides is usually not effective: it depends on the pathogenhow deep below soil surface it can live and it is unclear how deep the fungicide will go. Somepathogens live inside plant debris in the soil, where they are protected from fungicides. From anenvironmental point of view, it is dangerous to apply fungicides to soil. What is the effect on thebeneficial microorganisms that decompose plant rests? Will the pesticide contaminate the groundwater? How long will the pesticide persist in the soil?149 Cabbage Ecological Guide - 2000