Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Diseases of EggplantManagement and control practicesPrevention activities:• Location: avoid placing the nursery in a densely shaded or humid place.• Disease chances will be reduced if fields are deeply plowed at least 30 days before planting to allowtime for old crop and weed residues to decompose.• Remove and destroy crop left-overs as these may contain spores of damping-off fungi (and otherpathogens).• Make sure the nursery is well drained and the soil is soft and crumbly.• Do not apply high doses of nitrogen. This may result in weaker seedlings which are more susceptibleto damping-off. Usually, when organic material has been incorporated in the soil before sowing, thereis no need to apply additional fertilizer.• Add lots of compost or other decomposed organic material (15 to 20 tons/ha). Compost containsmicro-organisms and it feeds micro-organisms already in the soil. An active population of microorganismsin the soil may outcompete pathogens and will often prevent disease.• Crop rotation: If you are raising eggplant seedlings every season, use fresh soil that has not beenused for eggplant or other solanaceous crops for at least 2 years. Plant another crop (not asolanaceous crop) in the ‘old’ eggplant nursery.• Use vigorous seed or seedlings. Slowly emerging seedlings are the most susceptible.• Good results have been obtained with use of the antagonist Trichoderma sp. For example,application of Trichoderma harzianum is recommended by the Dept. of Agr. Extension in Thailand toprevent damping-off. The Trichoderma should be mixed into the soil before transplanting.• An interesting option is the use of fortified compost. This is compost that contains the antagonisticfungus Trichoderma. Trichoderma is added to the compost after the primary heating period ofcomposting is complete. The Trichoderma fungus increases to high levels in the compost and whenadded to the soil, they are as effective as, or in many cases more effective than chemical fungicidesfor control of a number of soil-borne diseases, such as damping-off. See section 3.8.3.1 on compost.• Use seed that is coated with a fungicide layer or with a layer of biological agents. See section 3.6.• Soil sterilization is practiced in many countries, often as a preventive measure before sowing. Thereare many methods to sterilize small areas of soil. See details in section 3.10.1.• Consider using a layer of sub-soil (taken from a layer of soil below 30 cm) to prepare raised nurserybeds. See section 3.10.1.3 for details.Once disease symptoms are found in the nursery:• Unfortunately, the seedlings that are affected by damping-off cannot be saved. To prevent thedisease from destroying all plants in the nursery, you may consider uprooting the healthy seedlings ifthey are large enough to survive in the field. Chances of success, however, may not be too great andmany seedlings may still die. If the seedlings are still small, they cannot be transplanted.• Uproot and destroy diseased seedlings to avoid build-up of the pathogen population.• When the nursery soil is wet or waterlogged, dig a trench around the beds to help drain them. It mayslow disease spread to other parts of the nursery.• If soil sterilization is not an option or is impractical, do not use the infected area for nurseries for atleast 2 seasons.• In some areas, fungicides are being used to control damping-off. Results vary however. In this guidefungicide use is not recommended for control of damping-off.Points to remember about damping-off:1. Damping-off is a serious nursery problem, caused by several soil-borne pathogens.2. Damping-off occurs in areas with poor drainage or areas with a previous history of thedisease.3. Crop rotation (including nursery site), proper drainage and sanitation practices (removing cropleft-overs) are ways to prevent disease problems.4. Good prevention of damping-off can be achieved by adding compost or other decomposedorganic material (15 to 20 tons/ha) to the soil regularly and before sowing or transplanting.5. Additional prevention can be obtained with use of antagonistic fungi, such as Trichoderma sp.133Eggplant Ecological Guide