Biocontrol of selected soilborne diseases of tomato and pepper plants

Biocontrol of soilborne diseases of tomato caused by Rhizoctonia solani and Pythium ultimum alone or in combination with Sclerotium rolfsii and Fusarium oxysporum f. sp. lycopersici were studied in the greenhouse and field. Soilborne diseases of pepper caused by the first three pathogens were also studied alone or in combination with Phytophthora capsici. Tomato and pepper seeds were treated with biomass of Gliocladium virens (G1-3) and Burkholderia cepacia (Bc-F)I individually and in combination, and planted in pathogen-infested soilless mix. Seedling stands for tomato from treated seeds were comparable to that in non-infested soilless mix. Although seed treatments with individual biocontrol agents reduced damping-off in peppers, only the G1-3 + Bc-F treatment resulted in stands similar to the non-infested control. When healthy seedlings of both crops were transplanted into pathogen-infested soil/soilless mix in the greenhouse, and supplementary root drenches of suspensions of GI-3, Bc-F, and G1-3 + Bc-F were applied, the plant fresh weight was significantly greater and the disease severity (DSI) significantly less than for infested controls. When transplants were set out into infested field plots, the combined GI-3 + Bc-F application resulted in greater fresh weight and lower DSI for pepper. and greater fruit yield for tomato than those obtained with either G1-3 or Bc-F alone. (C) 1998 Elsevier Science Ltd. All rights reserved.