BIOLOGICAL CONTROL OF BEAN DAMPING OFF CAUSED BY RHIZOCTONIA SOLANI

Isolates of Trichoderma spp. reduced the radial growth of Rhtbsc­tonla solani (Kuhn) by 59.6 — 78.4 % and Gliodadium spp. Inhibited the radial growth of RsoIan! by 57.2 —70.1%. Soil treatment with T.hamatum, T. harrianum, T.vitide and Gliodadium Wrens gave the maxi­mum protection against pre and post-emergence damping-off and re­duced the disease incidence from 50 to 6.6, 10, 10, and 10 % respec­tively, compared with the fungicide Rizolex at 10 %. Also, improved plant heights, fresh and dry weight, increased dry seeds yield from 4.5 with the control to 8.8, 8.7,8.6 and 8.5 gm in the above treatments, re­spectively, in comparison with Rizolex (8.2 gm) .The seed treatment with the bioagents was less effective than soil treatment. The soil treat­ment with antagonists remarkably reduced the population of R.solani in the soil from 30.5 to 0.01,0.03, 0.05, and 0.06 x 10⁶ cfu respectively, in unsterilized soil after 6 weeks from sowing. The seed treatment with the antagonists was less effective. The bioagents gave persistent effect in reducing R.solani population for more than 6 weeks, while Rizolex was superior up to 3 weeks from sowing.