Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

__________________________________________________________________________________Major Diseases of EggplantControl of Fusarium BY Fusarium…..! Family feud at micro level…!There are many strains of Fusarium oxysporum fungi that cause wilting of plants. A specific strain ofFusarium oxysporum is actually highly effective at controlling Fusarium wilt of tomato and othercrops. They work against their own “family members”! These isolates consistently provide 50-80%reduction of disease incidence in repeated greenhouse tests. They work against the pathogenicstrain because they “block the entry” so the pathogen cannot enter the plant.Commercial products such as “Biofox C” and “Fusaclean” are now available in the USA containingthe non-pathogenic Fusarium oxysporum. The product is used as seed treatment (dust formulation)or incorporated into the soil (granule formulation).For details on commercial biocontrol products check “The BioPesticide Manual” (Copping, 1998), orseveral internet sites such as www14 and www15 (see reference list, chapter 11).There are several other antagonistic organisms that control Fusarium and/or Verticillium, such asBacillus subtilis, Burkholderia cepacia, and Streptomyces griseoviridis. Different strains of theseantagonistic organisms have been registered as biocontrol products to control fungal wilt and some other(soil-borne) plant diseases in the United States (refs. www14, www15)Management and control practicesPrevention activities:• Using resistant or tolerant varieties is the best prevention of wilt disease. Some resistance to bothVerticillium and Fusarium wilt is found in eggplant varieties. See examples in table in section 3.2.2.• Locally produced seeds should be used only from plants free of any signs of wilt disease. Locallyproduced seeds should be hot-water treated or coated with a fungicide or an antagonistic fungus(when available). See sections 3.3 and 3.6.• Healthy planting material: seedlings that are suspected of having wilt disease (or any other diseases)should not be transplanted into the main field.• Maintain a high level of plant vigor with appropriate fertilization (especially not too much nitrogenshould be applied) and irrigation.• Plant in well-drained soil.• Keep rotational crops weed-free (many weeds are hosts of Verticillium and Fusarium).• Preventive application of Trichoderma sp. where available may be tested. This may be onlyeconomic in fields with a history of soil-borne diseases.Once disease symptoms are found:• Infected plants should be removed carefully and burned or composted outside the field. The soil fromwhich that plant was pulled however, is still infected. Removal of infected plants will at least reducethe increase of the fungal population. After the final harvest, remove and destroy all infested plantmaterial including the roots.• The wilt disease is increased by cultivation of the land, such as weeding.This is possibly because of root disturbance and thus increased rootdamage which form entry points for the fungus.• Application of biocontrol products such as Trichoderma sp. or otherswhere available may be a good option for control of soil-bornepathogens. See section on antagonists above.• Grafting: where soils are infested with fungal wilt organisms, there is anoption to graft eggplant seedlings on resistant rootstock (can be wildeggplant varieties). This means that initially both the rootstock and theeggplant seedling are grown. When they reach a certain vegetativestage, the stems of both the seedling and the rootstock are cut and thestem of the seedling is placed on the rootstock stem and tied together.The two will merge and continue growth. This way the rootstock151Grafting tomato onrestistant rootstock(from: Messiaen, 1992)Eggplant Ecological Guide