Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

___________________________________________________________________________________Major Agronomic PracticesBacterial wilt suppression with compost: Study results from Hai Phong, North VietnamDuring field studies on disease management, farmers set up a study on the use of compost tomanage bacterial wilt on tomato. Bacterial wilt is a major problem in many solanaceous cropsincluding eggplant. The tomato study was conducted in a field (with history of bacterial wilt) of 1400 m 2and consisted of three treatments (three replications):1. Use of compost (about 14 ton/ha fully mature – applied in planting hole before transplanting),using pesticides only when necessary following agro-ecosystem analysis2. Use of compost (as in 1) mixed with crushed lime3. Farmers practice (using only half mature compost – applied in planting hole beforetransplanting; following local practices in pesticide use)The insect pest levels and the blossom end rot incidence were similar in all treatments. Bacterial wiltincidence was too low to draw conclusions about the effect of the treatments. Yellow wilt (fungal wilt)was low as well, even though highest in treatment 3. Pesticide use dropped from 11 applications intreatment 3 to 7 applications in treatments 1 and 2. The crop development data in the 3 treatmentsdid not differ a lot, but the farmers and trainers said that the plants were higher and that there weremore leaves, flowers and fruits in treatments 1 and 2 than in treatment 3. The yields were higher intreatments 1 and 2 (resp. 1200 and 1100 kg/sao) than in treatment 3 (800 kg/sao). The profitsincreased from 558,000 VND/sao in treatment 3 to 787,000 VND/sao in treatment 2 and 1,007,000VND/sao in treatment 1.Conclusions from the field and pot studies by the farmers and the trainers were: ☺• Tomato plants develop better and faster with compost than without.• Compost suppresses bacterial wilt.• Lime should be used during the composting process rather than mixed with compost before fieldapplication. This statement will be tested during follow-up experiments.(pers. comm. J. Vos, Oct. 1999; and www16)How to use compostAs most vegetables grow best on soils rich in organic matter, compost can always be added asmuch as possible to the field before planting. Ideal would be 20 tons/ha or 2 kg per squaremeter of land (1 kg is about as much as you can hold in two hands). In Nepal, therecommendation is to use 30 tons/ha.It is recommended to mix the compost into the soil about 2 to 4 weeks before planting. This willgive time for the micro-organisms to break down the parts of the compost so that the nutritionalelements will be available once the seedlings are transplanted. Also some competition with possiblepathogens in the soil may have occurred. Compost can also be added to the planting hole duringtransplanting.3.8.3.2 Cover crops, Green manure, and Living mulchCover crops are crops planted to improve the soil, for weed control, erosion prevention or for loweringmoisture loss (during hot season) rather than for harvest. Such crops are also often called “greenmanure” or “living mulch” although strictly speaking, the terms are slightly different. Cover crops andgreen manure are usually grown when the land is fallow whereas living mulch can be grown togetherwith the crop. Living mulch is usually a leguminous crop, such as clover or pea grass, which remains low,covers a wide area, and is long lasting as it is being grown over several seasons.Cover crops can gradually add organic matter to the soil and help retain soil nutrients from one season tothe next. The contribution to soil organic matter and soil fertility varies with the kind of cover crop used.For example, legumes decay quickly because residues are high in nitrogen. Therefore, they are morevaluable as N sources than as organic matter sources. Grass crops, such as rye or jute, will have a muchgreater effect on soil organic matter content than legumes because they have a higher carbon to nitrogen(C:N) ratio and decay more slowly.27Eggplant Ecological Guide