Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Diseases of Eggplant• Use of lime is often recommended for control of soil-borne pathogens. The effects of limeare not clear. It may have an effect on micro-climate in the soil, stimulating antagonistic microorganisms.It may have an effect on nutrient availability, “boosting” the crop through adverseconditions.• Grafting: where soil is infested with bacterial or fungal wilt organisms, there is an option to grafteggplant seedlings on resistant rootstocks (usually wild eggplant varieties, e.g. Solanum torvum).This means that initially both the rootstock and the eggplant seedling are grown. When they reach acertain stage, the stems of both the seedling and the rootstock are cut and the stem of the seedlingis placed on the rootstock stem and tied together. The two will merge and continue growth. This waythe rootstock (resistant) is not affected by wilt diseases and the seedling will produce normal fruits.See section 3.13.• Chemical control of bacterial wilt is not recommended!Points to remember about bacterial wilt:1. Bacterial wilt is a serious soil-borne disease that can cause total loss of plants in large parts of afield.2. Some general management practices such as crop rotation, and sanitation of the field help toprevent and reduce disease.3. Interesting results have been obtained with adding organic matter such as compost into the soil.This is possibly due to stimulation of antagonistic fungi in the soil and better nutrition for theeggplants.4. Chemical control of bacterial wilt is usually not effective.5. Biological control agents such as non-pathogenic Pseudomonas sp. may become available in Asiain the future.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual:3-B.5. Identification of bacterial wilt3-B.6. Study of symptom development of bacterial wilt3-B.9. Test effect of liming on bacterial wilt development3-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 diseases3-B.15. Grafting to overcome bacterial wilt in tomato or eggplant8.3.2 Verticillium and Fusarium wiltSee photo 20 (page 177).Causal organisms: fungi - Verticillium sp., Fusarium oxysporumFusarium wilt in solanaceous crops is caused by several different strains of the fungus Fusariumoxysporum. These are: F. oxysporum f. sp. melongenae (eggplant), F. oxysporum f. sp. lycopersici(tomato), and F. oxysporum var. vasinfectum (pepper). Fusarium wilt in potato is caused by a complex ofup to four different Fusarium sp. All of the Fusarium wilt pathogens are generally specific to their hosts.Weeds of the solanaceous family can be colonized too.Although Verticillium and Fusarium are very different fungi, the symptoms caused in eggplant are similarin appearance and the difference between the two diseases is very hard to tell in the field. Given the soilbornenature of both fungi, and the similarities in the disease management of these wilts, they will bedescribed in this section together. However, it should be emphasized that although disease symptomslook similar, there may be differences in other aspects and some of those will be listed below.Both fungi attack a wide range of plant species, including many cultivated crops and weeds.Solanaceous crop plants like tomato, potato, pepper, and eggplant can all be infected.Signs and symptoms149Eggplant Ecological Guide