Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Diseases of Eggplant8.2.1 Phomopsis rot - Phomopsis vexansSee photos 21 and 22 (page 177).Causal organism: fungus - Phomopsis vexansOther common names: Phomopsis fruit rot, Phomopsis blight, and foot rotSigns and symptomsAll above-ground parts can be affected at all stages of development. Spots generally appear first onseedling stems or leaves. Spots may girdle seedling stems and kill the seedlings.Leafspots are gray-brown, clearly defined, circular spots with a narrow dark brown margin. In time thecenter of the spot becomes gray, and black pycnidia (fungus reproductive structures that appear as smallspecks) develop in this area. Affected leaves may turn yellow and die.Stems can also be affected: lesions are circular and may also contain pycnidia.Fruit spots are similar to those on the leaves but are much larger: large, circular, sunken tan or blackareas on the fruit. Affected fruits are first soft and watery but later may become black and shriveled.Pycnidia also appear on fruit spots, usually in circular forms.Source and spreadPhomopsis persists in and on seeds and survives in residue from diseased plants. In addition, it isspread through splashing water.Role of environmental factorsDisease is promoted by wet weather and high temperatures.Natural enemies/antagonistsUnknown.Management and control practicesPrevention activities:• Planting resistant varieties is the most effective prevention. Resistant varieties from the USA areFlorida market, Black pride, and Special Hibush (Peet, www1). See table in section 3.2.2.• Use certified seed.• Use a three year crop rotation. See section 3.17.• Sanitation: clean up plant debris where the pathogen can survive and spread to new (solanaceous)crops.Once disease symptoms are found:• There are fungicides that may be able to kill the fungus and stop the spread. Note that somebeneficials and natural enemies of insect pests may be killed by fungicide sprays as well!Points to remember about Phomopsis rot:1. Phomopsis rot can affect seedlings, leaves, stems, and fruits. Circular spots containingpycnidia (tiny black specks) are typical for this fungal disease.2. Phomopsis rot persists in and on seed, and survives in residue from diseased plants.3. Resistant varieties exist. Check with local seed supplier.4. Good crop sanitation, use of clean seed, and a three-year crop rotation schedule may helpprevent disease.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual:3-A.1. Study of symptom development of leaf spots: classroom exercise3-A.2. Study of symptom development of leaf spots: field exercise3-A.3. Effect of infection of the seed bed3-A.4. Effect of the use of infected planting material3-A.5. Test effect of hot water seed treatment3-A.6. Use of subsoil to manage leaf spot diseases in the nursery3-A.7. Soil solarization to manage leaf spot diseases in the nursery139Eggplant Ecological Guide