Characterization and Pathogenicity of Blast Pathogen (Pyricularia grisea of Wild Finger Millet (Eleusine Africana and its Control Using Biological Antagonists and Fungicides

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Addis Ababa Universty


Blast (Pyricularia grisea) is an important disease of wild finger millet (Eleusine africana). It causes disease on a wide variety of alternative hosts including agriculturally important plants such as finger millet (E. coracana) in Ethiopia. A total of twenty six isolates of P. grisea were isolated from infected wild finger millet plants from 5 different zones of Ethiopia. From the initial twenty six isolates, only nine isolates were selected for the detailed morphological, cultural, physiological and biochemical characterization based on their geographical location and isolate type, whether it is isolated from stem, leaf, neck or seed parts. Among the different media used host seed extract + 2% sucrose agar and oatmeal agar were found to be the best for mycelial growth and sporulation of the isolates, dextrose was the most preferred among the carbon sources and NaNo3 proved to be the best source of nitrogen for all the isolates. The shape, color and compactness of the fungal colonies varied with the media used. At pH 6.5 all the isolates exhibited maximum mean dry mycelial weight, and found optimum pH. The optimum temperature range for the maximum growth of the isolates of P. grisea was found to be 20°C to 30°C. All the six P. grisea studied under green house for their pathogenicity, were able to infect all the tested varieties. Among an In vitro evaluated fungicide against the test pathogen, both Curzate and Sancozeb fungicides showed varied levels of antifungal activity and the highest concentration (800 and 1000ppm) of fungicides were found of inhibiting the growth of the isolates of P. grisea. With regard to the efficacy of the fungicides, Sancozeb was found to be the most effective to inhibit the isolates. Among in vitro tested biocontrol agents viz. Trichoderma viride, Trichoderma harzianum and Pseudomonas fluorescence, the growth of Trichoderma species was fast, the clear inhibition zones were not formed in all incubated Petri plates, therefore it was more effective than the bacterial antagonist. Compatibility of the biocontrol agents with different fungicides (Curzate and Sancozeb) that is., Trichoderma harzianum and Trichoderma viride in an in vitro condition resulted in that, both Curzate and Sancozeb, in lower concentrations (100, 200, and 400ppm) were found well tolerated with both Trichoderma species and hence they were shown effective in managing plant pathogens. Combining antagonists with synthetic chemicals eliminates the chance of resistance development and reduces the fungicide application. Keywords: Finger millet, Pyricularia grisea, biocontrol, fungicide, compatibility, pathogenicity



Finger millet, Pyricularia grisea, Biocontrol, Fungicide, Compatibility, Pathogenicity