Some fungal and bacterial bioagents as well as an actinomycte isolate were
screened for their antagonistic effects against Sclerotium rolfsii, Rhizoctonia solani,
Macrophomina phaseolina, Fusarium oxysporum, and Fusarium solani in vitro.
Trichoderma hamatum, T. harzianum, and T. pseudokoningii, as well as certain isolats
of Bacillus subtilis and one isolate of Pseudomonas f1uorscens were the most effective
bioagents in suppressing the radial growth of the four patboqens. Yet, they were less
effective in retarding growth of Fusarium spp. as compared with the other pathogens
under study. T. hamatum, T. harzaium, P. f1uorescense and B. subtilis under greenhouse
(S. rolfsii-infested soil) and field (natural infection) conditions may be utilized to
biological control of sugar beet damping-off and root rot diseases. Three different formulae, suspension, powder, and granules were prepared from T.
hamatum, B. subtilis and Actinomyces isolate, to be utilized in field application. The
most effective bioagent for controlling the seedling blight was Rhizo-N followed by the
suspension of B. subtilis which exhibited the least percentage of seedling blight. While
the least affective one was Plantguard the granules of Actinomyces, and B. subtilis.
For controlling the root-rot diseases, the most effective bioagent was T. hamatum
(powder), while B. subtilis (suspension or granules) and Actinomyces (granules) were
the least effective bioagents in this respect. These treatments also caused an         increase in root yield per plot.                                                .