Cabbage Integrated Pest Management : An Ecological Guide.

Disease Ecology7DISEASE ECOLOGYSUMMARYDisease ecology studies pathogens that cause plant diseases in relation to theirenvironment.Cabbage diseases are caused by pathogens such as fungi, bacteria, viruses andnematodes.Most pathogens spread attached to or inside seeds, or infected plant material, orare carried with wind, water (rain, irrigation water, ground water), through insectsand by humans or animals (attached to cloth or skin, and transported with plants/harvested crops).A disease is the result of interactions between a pathogen, a host plant and theenvironment. These interactions are shown in the disease triangle.pathogenenvironmenthostPathogens can infect a plant when 1) the variety of that plant is susceptible to thedisease, 2) the disease is present and virulent (able to infect the plant), 3) theenvironment (e.g. humidity, temperature) is favorable for the disease to develop.Disease management is focused on changing or influencing one of these threeelements to prevent the disease from attacking the plant. Studying disease in thefield, or setting up field experiments is an excellent way of finding out if symptomsare caused by a disease and how some (environmental) factors influence diseasedevelopment. Knowing characteristics of a disease will give you clues on how tomanage it!Available fungicides and bactericides are often not effective enough to stop anyof the major cabbage diseases, especially during prolonged periods of wetweather. If at all necessary, fungicides should be combined with structural managementmethods like adding organic material to the soil (compost), crop rotation,sanitation, etc.The antagonistic fungi Trichoderma sp. have become widely available in manycountries in South East Asia. Trichoderma sp. can suppress several soil-borneplant pathogens in vegetables. More biological agents may become available forcontrol of plant diseases in the future.Cabbage Ecological Guide - 2000136