SEMINAR SERIES

FALL 2015

Effect of biochar and vermicompost soil amendments on root-knot nematodes and fungal root rot

disease of common bean in Western Kenya

presented by

Luiza Munyua and Samuel Were PhD Candidates, Plant Science and Crop Protection, University of Nairobi/

Visiting Scholars, Cornell University

Thursday, September 17, 2015 12:20 – 1:10 pm

135 Emerson Hall ABSTRACT: Common bean (Phaseolus vulgaris L.) is a grain legume grown on more than four million ha annually in Africa and provides dietary protein for over 100 million people in rural and poor urban communities. In Kenya, it is the third most important staple food having a critical relevance to the national food security. Root-knot nematode and root rot disease complexes are often considered the major constraints to bean production, reducing both yield and quality to as much as 70% reduction of some popular commercial bean cultivars in Kenya. We sought to establish the incidence and severity of fungal root rot disease and plant parasitic nematode infection on beans grown on small holder farms in Western Kenya and to use organic matter amendments comprised of biochar and vermicompost to reduce their incidence and severity. Farms were located in three regions of western Kenya, representing four agro-ecological zones. Disease incidence and gall scoring was recorded during active plant growth. Pathogen isolation and extraction was done from the diseased roots and soils to establish the cause as well as identify the pathogens. Two years of field data, across four planting seasons, indicate that both biochar and vermicompost soil amendments led to a decrease in root-knot disease relative to control plots. Root rot disease incidence was also reduced in amended plots. Bean yield productivity improved where biochar and vermicompost were incorporated separately and in combination, relative to control plots. The use of these organic soil amendments will help the small scale bean farmers achieve greater agronomic success, increased bean productivity and more reliable return on their investments in bean cropping as well as long term sustainable benefits in terms of improved soil health.

Light refreshments will be served starting at noon.