INTEGRATED MANAGEMENT OF BACTERIAL WILT OF TOMATO IN GREENHOUSE

摘要

Surveys and collection of bacterial wilt of tomato and infested soil samples were carried out in Changwat Phetchaburi and Changwat Udontani. Twelve strains were isolated and characterized for pathogenicity, biochemical and physiological properties. All of them are identified as Ralstonia solanacearum (Smith, 1896) biovar 3. New isolated strains are more virulent than old isolated strains when tested on susceptible tomato cultivar Seeda. Investigation on disease incident and resistant reaction of four cultivars (cv.), Seeda, New - Kingkong, BL341 and BL321 against 5 strains of R. solanacearum, To - Ud1, To - Ud2, To - Udk 2, To - 1342 and To - 4 found that all 4 cv. of tomato were susceptible to strain To - 1342 and moderate resistance to strain To - 4 whereas cv. BL341, BL312 and New - Kingkong and Seeda were moderate resistance, moderate susceptible and susceptible to 3 new strains (To - Udl, To - Ud2 and To - Udk 2), respectively. Evaluation of biological control activity against R. solanacearum strain To - Udk2 using Bacillus subtilis strains CH_4 and CH_6 and Pseudomonas fluorescens strains CR - S02 and CM - R03 under laboratory and greenhouse conditions showed similar promising inhibition but B. subtilis was better than P. fluorescens. Antagonists strain CH_6 provided 60 percent tomato survival which was the most efficient whereas control without antagonists was no survival (0 percent) of tomato. In greenhouse at Asian Institute of Technology, formulated powder of strain CH_6 gave better biocontrol of bacterial wilt than suspension form and triple applications at 7 days interval has more effective control than single application. Application of antagonist CH_6 with plant extract of Chung Chia (Zanthoxylum rhetsa) to the soil, bacterial wilt incidence was delayed for 4 weeks after inoculation with R. solanacearum strain To-Ud3. However, application of plant extract alone provided better control than the combination application with antagonist.