In vitro evaluation of some fungicides and bioagents against common bean anthracnose (Colletotrichum lindemuthianum Sacc. Magnus) Briosi Cavara

Bean anthracnose caused by Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi & Cavara is one of the most devastating seed-borne diseases of common bean (Phaseolus vulgaris L.) in Ethiopia. The aim of the present investigation was to evaluate the antifungal activities of bioagents and fungicides which can be used to control bean anthracnose. Three fungicides viz., Mancozeb, Folpan and Mancolaxyl, and three bioagents viz., Trichoderma harzianum Rifai, Trichoderma viride Pers. Fr. and Pseudomonas fluorescens Migula, were screened in vitro for their antifungal activities against common bean anthracnose, C. lindemuthianum using the dual culture and microtitre double-dilution techniques. Antagonistic effects of the three bioagents tested by the dual culture method showed highly significant (P<0.01) percentage of inhibition of the mycelia germination of C. lindemuthianum. The highest percentage of inhibition of the mycelia germination (80.39%) was obtained from T. viride, followed by 75.49% from T. harzianum and 40.2% from P. fluorescens. Similarly, highly significant (P<0.01) differences were observed in the radial growth of mycelia of C. lindemuthianum. The highest growth of mycelia (3.4 cm) was measured from the control (C. lindemuthianum), whereas the least (0.67 cm) was obtained from the dual culture containing T. viride. The in vitro assays revealed that all the antagonistic bioagents produced siderophores which were capable of inhibiting mycelia growth of the pathogen. The mancozeb fungicide was found to be fatal to C. lindemuthianum at four different concentrations poisoned on potato dextrose agar medium. Key words: Bio agents, Colletotrichum lindemuthianum, dual culture, fungicides, in vitro, Phaseolus vulgaris.