Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

___________________________________________________________________________________________Disease EcologyWhen resistant varieties are not available, find out some more details on the disease. Start for examplewith: where does the disease come from? How does it spread?Knowing characteristics of a disease will give you clues on how to manage it!The table below summarizes some sources and carriers for a number of important eggplant diseases.DISEASEseedsotherinfectedplants andweedsSOURCE(S) and/or CARRIER(S)soil contaminated(ground)waterdiseasedcropresiduescarriedby windtools,people,animalsinsectvectorsdamping-off - - + + + - + -root rot - - - + + - + -rootknot - + + + + - + -nematodesPhomopsis+ -rot + + + - - +early blight + + + - - + + -little leaf - + - - - - - +bacterial + + + + + - + -wiltstem rot -/+ + + + - - + -By checking the “+” symbols, you can see what the important sources and carriers for a disease may be.Next thing is to see if these sources/carriers can be modified. By eliminating or reducing a source or acarrier of pathogens, disease may be reduced! Some examples of management practices are listedbelow. This list is not exhaustive, check sections on individual diseases for a complete set ofmanagement practices.contaminated seeds: sterilize seeds before sowing (section 3.6),other infected plants: uprooting diseased plants, pruning infected leaves, increasing plant spacing,diseased crop residues: sanitation – removing all left-overs from previous crop from field,soil:crop rotation, for small areas, soil sterilization may be an option (section3.10.1)contaminated water: avoid planting down-hill of an infected field,carried by wind:cooperation with other farmers for sanitation practices, covering compostpiles, windbreaks (though usually of limited value),contaminated tools, clean tools, shoes, etc. when used in field, avoid working in thepeople, animals, insects: field when plants are wet, control vector insects.Another factor to influence disease is the environment (see disease triangle, section 7.5). When youknow what environmental factors stimulate or inhibit the disease, you can sometimes influence these.Soil temperature may be influenced by mulching; humidity can be influenced by proper drainage of thefield, using furrow irrigation instead of overhead irrigation, etc.Even with all the knowledge, it remains a difficult task to manage diseases. When all preventive activitiesfail, there may not be another option but to use a fungicide. However, from an ecological and aneconomical point of view, there is a lot to gain by setting up small experiments to test when and how toapply fungicides, to control diseases in your field, this season. Remember that natural enemies of insectpest and antagonistic organisms may also be harmed by fungicide sprays.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual:1.4. Effect of pesticides on spiders and other natural enemies3.6. Disease triangle to explain disease management3.7. Demonstration of spread of pathogens3.11. Simulating pathogen spread126Eggplant Ecological Guide