Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

___________________________________________________________________________________Major Agronomic PracticesThe term ‘structure’ refers to the arrangement of the different particles into soil aggregates. The microorganismsin the soil are responsible for mixing the soil and building of soil structure. Soil particles arebound together by fungal branches and bacterial gums. These help to bind them into aggregatesbetween which the pores are formed that hold air and water. In the pores between the aggregates, thesoil air is found, an important source of oxygen for root respiration. Like humans, most plants and theirroots need air (oxygen) for respiration! A good soil structure permits the movement of water through thesoil and it facilitates the development of a good root system. A good soil can be compared with a newsponge that can absorb plenty of water.The best part of the soil is the dark layer of topsoil, whichtakes many years to develop. Topsoil is rich in plant nutrientsand beneficial soil organisms. Under the topsoil is the yellow,light brown or reddish subsoil which may be more acid and isharder for plants to grow in. Humus is the more or less stablefraction of the soil organic matter remaining afterdecomposition of plant and animal residues. Adding organicmaterial such as well-rotten compost, improves the structureof most soil types including heavy clay and lighter sandysoils. The organic matter should be properly composted(well-rotten).Eggplant is moderately deep-rooting and can be grown on a wide range of soils. It does best on lighttexturedsoils that are deep and well-drained, such as sandy loam. The optimum soil temperature forgrowth is 23° to 32°C. A soil pH in the range 6.0–6.8 is desirable. See section 3.7.5 on soil pH.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual:2-A.3. Soil structure and effects on root growth2-A.8. Soil test kits3.7.3 Soil infectionNext to the beneficial decomposers or neutral organisms in the soil, soil may also contain organisms thatare harmful to the crop. These may include insects and pathogens like fungi, bacteria and nematodes.Soil-borne pathogens can enter a field in numerous ways. They may be attached to pieces of soil on theroots of seedlings, to soil particles on field tools, or with bits of soil on your slippers or shoes! They mayalso spread with the ground water.Study example on soil infection: experience from Hai Phong, VietnamDuring studies, farmers conducted pot experiments with tomato and cucumber to study the effect ofclean soil and/or irrigation water on disease spread and infection. The group compared plants grownin pots filled with clean soil, with infected soil or combinations of clean soil and infected irrigationwater versus clean water. They concluded that disease can be harbored in crop residues, soil orwater, and that a combined approach to disease management has to be taken, including fieldsanitation, roguing of diseased plants and using them for composting, and crop rotation (paddy rice -paddy rice - cucumber) (pers. comm. Dr. J.Vos, March 2000; Vos, www16).Pathogens are so small that they cannot be seen with the naked eye. Only when they affect the plants dothey become apparent. At that point, some injury to the plants has already occurred. And, maybe evenmore important, once there is a disease in the soil of the field (soil-borne disease), it is very difficult to getrid of it. Many pathogens can survive for a long time in the soil, even without a host plant! Therefore, it isessential to prevent soil-borne diseases from entering the field and attacking the plants.16Eggplant Ecological Guide