Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Diseases of Eggplant1999) for example, showed that 8 out of 66 genotypes of eggplant were resistant. It will takeprobably some years before such lines will become available varieties. It is advised to test varietiesfor resistance or tolerance to pests and diseases in a varietal trial.• Eradication of solanaceous weeds that may serve as hosts.• Control of jassids, which may carry this disease into the field.• Planting time: In Madhya Pradesh, India, early sown eggplant crops (third week of June) becameless diseased than those sown in July or August, due to differences in leafhopper vectorpopulations. Continuous cropping of the same cultivar increased disease incidence, as did thepresence of weeds, sweet potato or tomato crops nearby which helped to increase vectorpopulations (Keshwal, 1986).Once disease symptoms are found:• Uproot diseased plants as soon as they are detected. These plant serve as a source of infection!• In field trials from India under natural infection, little leaf disease was controlled best by dippingseedlings in tetracycline followed by a soil application of phorate (Maheshwari, 1988). Other studiessuggest that spraying and root immersion were efficient ways of treating the plants as wasevidenced by the amount of tetracycline uptake (Verma, 1978).• Research from India reported tetracycline therapy to be effective in controlling this disease. Thesymptoms are suppressed. However, if the disease occurs only at a few plants in the field, it isprobably easier and cheaper to rogue these plants and burn them outside the field or use them forcomposting. See section 3.8.3.1 for proper composting methods.Points to remember about little leaf:1. Little leaf is a disease that results in bushy plants without fruits.2. Little leaf is caused by a mycoplasma (phytoplasma), transmitted by jassids.3. Growing resistant or tolerant varieties where available, control of jassids, and removinginfected plants from the field (sanitation) are ways to prevent and reduce disease incidence.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual:3-F.7. Role play on effects of pesticides on virus transmission by insect vectors2-C.4. Testing of cultivars8.2.4 Anthracnose Fruit RotCausal organism: fungi, several species.Fungi causing anthracnose of eggplant fruits include Colletotrichum melongenae and Gloeosporium sp.The anthracnose fungi can attack several solanaceous crops including eggplant, tomato and pepper.Signs and symptomsSmall, water soaked, circular spots develop under the skin of fruit as it ripens. Those spots can appearon both unripe and ripe fruits The spots become sunken and dark. Numerous dark specks, the fruitingbodies of the fungus, develop in the lesions often in radiating circles around the center. In moist, warmweather, these black bodies ooze gelatinous pink spore masses. Spots vary from one to several on thefruit surface. In warm weather the fungus and soft rot bacteria which enter the split skin over the lesionsspread internally forming a semisoft decay which makes the fruit worthless.Severely infected fruits drop to the ground with the pedicel still attached to the plant. The eggplant seedmay be infected and often seedlings have the disease, which later moves into the developing foliage.Such infections are often unnoticed until the fruits start to grow, at which time the fruit rot phase maybecome serious.Source and spreadAnthracnose causing fungi survive between crops on infested plant debris in the soil. Early in the growingseason, spores from the soil splash on lower leaves of the eggplant. Few symptoms develop on infectedleaves, but the spores produced on foliage can be carried by splashing rain to developing fruit. Infectedunripe fruits will not develop symptoms of anthracnose until they begin to ripen. Ripe fruit is very144Eggplant Ecological Guide