BIOCONTROL OF SELECTED SOILBORNE DISEASES OF TOMATO AND PEPPER PLANTS

Biocontrol of soilborne diseases of tomato caused by Rhizoctonia solan i and Pythium ultimum alone or in combination with Sclerotium rolfsii and Fusarium oxysporum f. sp. lycopersici were studied in the greenhou se and field. Soilborne diseases of pepper caused by the first three p athogens were also studied alone or in combination with Phytophthora c apsici. Tomato and pepper seeds were treated with biomass of Gliocladi um virens (G1-3) and Burkholderia cepacia (Bc-F)I individually and in combination, and planted in pathogen-infested soilless mix. Seedling s tands for tomato from treated seeds were comparable to that in non-inf ested soilless mix. Although seed treatments with individual biocontro l agents reduced damping-off in peppers, only the G1-3 + Bc-F treatmen t 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 su spensions of GI-3, Bc-F, and G1-3 + Bc-F were applied, the plant fresh weight was significantly greater and the disease severity (DSI) signi ficantly less than for infested controls. When transplants were set ou t into infested field plots, the combined GI-3 + Bc-F application resu lted in greater fresh weight and lower DSI for pepper. and greater fru it yield for tomato than those obtained with either G1-3 or Bc-F alone . (C) 1998 Elsevier Science Ltd. All rights reserved.