Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

___________________________________________________________________________________Major Agronomic PracticesThe irrigation method may also have consequences for the insect and disease populations. Overheadirrigation can increase diseases. The spores of early blight (Alternaria solani) for example, can easilygerminate when the leaves are wet . The use of ditch or furrow irrigation is usually preferred tooverhead irrigation. Ditches also ensure rapid drainage of excess soil moisture during the rainy season.Flooding the field by rotation with paddy riceIn Indonesia, chili grown in rotation with paddy rice had less problems with soil-borne diseasesand nematodes than chili grown in unflooded fields. During the rice production, the field is floodedand nematodes and other pathogens in the soil are killed (Vos, 1994).See section 3.17 on crop rotation.Other useful water management practices to help keeping foliage dry to prevent spread of water-bornepathogens include:• Planting in wide rows arranged to increase air flow between rows.• Orienting rows towards prevailing wind.• Planting with wide spacing in the rows.• Irrigating early enough to give plants a chance to dry before evening.• Working with plants only when leaves are dry.For eggplants, proper water availability is essential during early growth and during the time of floweringand fruit set. Lack of water during these periods may result in weaker plants, and could lead to reductionin fruit size and yield.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual:2-C.8. Flooding and overhead irrigation3.15 Intercropping and trap crops3.15.1 Intercropping and barrier cropsIntercropping is the simultaneous cultivation of two or more crops in one field. It can also be called mixedcropping or polyculture. When plants of different families are planted together it is more difficult for insectpests and diseases to spread from one plant to the next. Insects have more difficulty in finding hostplants when they are camouflaged between other plants. Fungus spores may land on non-host plantswhere they are lost. Natural enemies of insect pests can hide in the other crop. When the intercrop istaller than the eggplants they can form a “barrier” thus reducing spread of insect pests and diseases.Intercropping: growing two or more crops in one fieldCertain intercropped plants excrete chemicals or odors which repel insect pests of other plants.Examples are onion and garlic. The strong smell repels some insects, and they fly away and will notattack other plants growing between the onion or garlic plants. For tomato there are several study resultswith intercropping, some are given below. For example, intercropped tomatoes with onion or garlicreduced levels of whiteflies and aphids on tomatoes (Tumwine, 1999).43Eggplant Ecological Guide