Use of soil streptomycetes from Maseno (Kenya to inhibit growth of Pyriculariagriseainvitro cultures

Abstract

The most serious biotic constraint to finger millet worldwide is blast caused by the fungus Pyricularia grisea. Its management has been very challenging. However not a formidable control solution has been offered and therefore a need for other approachs. Actinomycetes belong to the phylum proteobacteria, they are gram +ve, terrestrial or aquatic with high guanine and cytosine content. Soil actinomycetes have antagonistic activity against a wide range of plant pathogens.This study isolated and characterizes some soil actinomycetes in Maseno area (Western Kenya) and studied their antifungal effect on P. grisea pathogenic on finger millet. Soil sample collected was dissolved in distilled water, homogenized and spread over modified Kuster’s agar. Colonies of actiomycetes were isolated as from the fourth day of incubation. . Finger millet heads and leaves displaying symptoms of blast were collected and Pyricularia grisea isolated on autoclaved powered finger-millet debris and maintained on PDA. A single steak of actinomycetes culture was made on a fresh Kuster’s agar and incubated for 3-4 days at 26 0C -28°C, and P. grisea, 20 mm, at right angles to the original streak of actinomycetes. The results indicate that isolates AT2 and AT4 are pathogenic to Pyricularia grisea and can be a basis for bio-control of blast in finger millet. Keywords: Finger milet, actinomycetes, pyricularia, proteobacteria, kuster’s agar, biopesticide