Three strains of the fungus Trichoderma harzianum Rifai and two strains of the bacterium Bacillus subtilis (Ehrenberg) Cohn were evaluated for their ability to suppress colonization and sporulation of the artillery fungus (Sphaerobolus stellatus Tode:Pers.) on oatmeal agar. All five biological control agents inhibited growth of S. stellatus, but efficacy depended on time of application. Simultaneous inoculation of agar with S. stellatus and the biocontrol agents, as well as inoculation of biocontrol agents 14 days prior to S. stellatus, resulted in complete inhibition of S. stellatus. Inoculation of agar with biocontrol agents 14 days after inoculation with S. stellatus reduced, but did not completely suppress S. stellatus colonization and sporulation. In this experiment, gleba (spore masses) treated with all strains of T. harzianum and strain GBO3 of B. subtilis did not germinate, but 13% of gleba treated with strain MBI 600 of B. subtilis did germinate. Trichoderma harzianum was more effective than B. subtilis as a biocontrol agent.
The authors acknowledge funding received from The Horticultural Research Institute, 1250 I Street NW, Suite 500, Washington DC 20005.
2Instructor of Forestry, Penn State Mont Alto, Mont Alto, PA 17237.
3Professor of Plant Pathology.
4Professor of Ornamental Horticulture.