Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Diseases of Eggplant(resistant) is not affected by wilt diseases and the seedling will produce normal fruits.• A soil pH of about 7 seems to be optimal to suppress this disease. See section 3.7.5. Liming canincrease the pH of the soil.• Long rotation: wilt disease is controlled (or reduced) by long term rotations with non-related cropsthat are not susceptible to wilt. Because Fusarium and Verticillium fungi are widespread and persistseveral years in soil, a long crop rotation (4 to 6 years) is necessary to reduce populations of thesefungi. Avoid using any solanaceous crop (potato, tomato, pepper, eggplant) in the rotation, and ifVerticillium wilt is a problem, also avoid the use of strawberries and raspberries, which are highlysusceptible. Rotate with cereals and grasses wherever possible. A 3 or 4 year rotation is usuallysufficient to reduce disease incidence although special fungus spores (so called microsclerotia)persist in the soil for 10 years or more. Reducing root lesion nematode populations helps control wiltbecause the wilt fungi often infect nematode-damaged root systems.• If soils are severely infested, production of solanaceous crops may not be possible. Soil solarizationand use of plastic mulch are other options described for control. However, soil disinfection is verydifficult because soil can be infested to at least 90 cm depth!Points to remember about fungal wilt:1. Verticillium and Fusarium wilt are caused by soil-borne fungi that can persist in the soil for manyyears.2. Use of resistant varieties, where available, is probably the best prevention.3. Several antagonistic organisms are available as biocontrol agents for control of fungal wilt but notall of these may be available in Asia. Trichoderma sp. may be tried as a preventive measure.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual:3-B.10. Symptom development study of fungal wilts3-B.11. Effect of sanitation on fungal wilts3-B.12. Test different cultivars for resistance to wilt diseases3-B.13. Raised plants beds to reduce wilt incidence3-B.14. Effects of inundation of fields on incidence of wilt diseases8.4 Stem rotThere are several organisms that cause stem rot to eggplant. Some are listed below, others aredescribed in other sections because the main symptoms are other than the rotting of stems. Forexample, early blight can cause a “collar rot” of seedlings near the soil line but major symptoms are leafspots and this disease has therefore been grouped in the leaf spot section.See key table in chapter 10.8.4.1 Sclerotinia stem rot – Sclerotinia sclerotiorumCausal organism: fungus - Sclerotinia sclerotiorumThe disease attacks over 170 species of plants. It causes white mold onbeans, cottony soft rot of carrot, watery soft rot of cole crops, root rot ofpea, among others. Symptoms vary with host plant.Signs and symptomsThe disease can be recognized by a soft, watery rot with white, moldygrowth on stems, petioles, and leaves of plants. Often initial infectionoccurs in the axes of branches or where a supporting string may be tied tothe base of the plant. These points accumulate nutrients, plant refuse, andmoisture on which the fungus can grow. Infection may start on leaves incontact with the soil and gradually grow through the petiole to the stem andeventually girdle it. If conditions remain moist, a large amount of cottony,moldy growth can be seen on the dead tissue. As this growth progresses,152Black sclerotia presentmainly in the pithEggplant (from: Ecological Blancard, Guide 1992)