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The biocontrol of black rot disease of okro caused by Macrophomina phaseolina  in Nigeria

David Babatunde Olufolaji: Federal Univ of Technology

<div><em>Macrophomina phaseolina</em>,the fungal pathogen of black rot disease of okra causes great loss in seed germinability and seedling establishment. <em>Trichoderma harzianum</em> an antagonistic biocontrol fungus and mancozeb chemical fungicide were bioassayed for antifungal attributes on the pathogen in Nigeria. <em>T.harzianum </em> and mancozeb were separately inoculated on the agar plates at 24, 48 and 72 hours before and after the introduction of <em>M.phaseolina </em>for both Prophylactic and therapeutic treatments. The inhibitory effect of <em>T.harzianum</em> and mancozeb were assessed. <em>In vivo </em>studies, involved the soaking of 20 okra seeds in spore suspension of <em>T. harzianum at </em>for 24 and 48 hours separately before and after the introduction of <em>M. phaseolina </em>for prophylactic and therapeutic treatments respectively. It was observed that at 72 hours <em>T. harzianum</em> had 92.11% level of mycelial growth inhibition on <em>M.phaseolina, </em>while mancozeb had 94.50% level of inhibition. <em>In vivo, </em>prophylactic treatment gave 50.00 and 66.65% for germination and seedlings emergence at 24 and 48 hours respectively which were significantly (p<u><</u> 0.05) higher than the therapeutics which gave 13.35 and 02.72% respectively. This is an indication that both the biocontrol agent and the chemical fungicide were able to inhibit the mycelial growth of the pathogen. However the biocontrol agent could be more preferable for disease control since it would be environment friendly and do not exhibit mammalian toxicity.</div>