EFFICACY OF BIOCONTROL AGENTS IN PLANTING MIXES TO COLONIZE PLANT-ROOTS AND CONTROL ROOT DISEASES OF VEGETABLES AND CITRUS

Tomato, bell pepper, celery and citrus were propagated in planting mix es amended with formulations of commercial biocontrol agents. Root col onization by selected biocontrol agents was evaluated for pepper, toma to and citrus, and found to be generally between 76 to 100% in both gr eenhouse ebb and flow, and bench-produced plants. Only colonization by Glomus intraradices was low, about 8%. All biological control agents, Trichoderma harzianum, Bacillus subtilis, G. intraradices, Gliocladiu m virens, and Streptomyces griseovirdis reduced crown rot of tomato in the field, with T. harzianum and B. subtilis being the most effective uniformly among four tests. Four biocontrols reduced Phytophthora roo t rot on citrus in the field, two applied as a drench to soil in pots reduced Thielaviopsis root rot on citrus, and two biocontrol agents in combination reduced celery root rot caused by Pythium and Fusarium sp p., however, none improved above-ground plant growth or health of citr us and celery. Pepper crown and root rot caused by P. capsici was redu ced by B. subtilis in one of two tests.