Quality status of farm saved bean seed in Maragua sub -county and management of seed-borne diseases by seed treatment

Abstract

Common bean ( Phaseolus vulgaris L .) is the leading food l egume widely grown in the world. In Kenya, beans play an important role of sustainable livelihood to millions of small scale fa rmers through provision of food security and income. However, farm saved bean seed is an important source of disease inoculu m for major bean diseases thus contributing to low bean production among small scale farmers. The overall objective of the study was to contribute to increased bean productivity through production of quality seed and reduction of seed - borne diseases by seed treatment. A survey to determine bean production practices was conducted in diverse agro - ecological zones of Muragua, Murang`a Cou nty. Samples of farm - saved bean seed varieties were collected from the farmers and analyzed for physical purity, germination and pathogens contamination . In addition, field experiments were conducted over two cropping seasons at Kenya Horticulture Research Institute Research (KA LRO ), Thika to evaluate the efficacy of seed treatment chemicals in the management of root rot fungi and seed - borne bacterial blight . The seed trea tment options evaluated were Seed plus® (ii) Apron star® 42 WS , Rootgard® , Funguran – OH 50WP® , Cruiser Maxx® , Monceren® 125 . Data was collected on stand count, incidence of root rot , bean stem maggot infestation, common bacterial blight incidence and seed yield. The study showed that beans are produced in small holdings of less than one acre and most farmers use uncertified farm - saved seeds. Farmers were found to grow a mixture of different bean varieties and root rots and bacterial blights were the commonly cited diseases. Very few farmers used chemicals during bean production to control pests and diseases. Only a few farmers from lower midland zone four (LM 4) reported relatively higher bean grain yield compared to lower highland zone one (LH 1) and upper midland zone two (UM 2). Most of the farm - saved bean seeds had less than the 9 5% re commended physical purity and contained high levels of discoloured and bruchid damaged seeds. Some of the samples met the required minimum germination percentage of 80%. The samples from different agro - ecological zones differed in the level of contaminatio n with fungal and bacterial blight causing pathogens. Samples from agro - ecological zone ( LH 1 ) had higher contamination levels. Seed treatment with chemicals significantly improved seed emergence and the stand count. Seed treatment with Cruiser Maxx® , Monc eren® and Apron star® 42 WS significantly reduced incidence of bean stem maggot ( Ophiomyia s pp . ). Certified seeds treated with Apron star® 42 WS significantly reduced infection with Rhizoctonia solani , Fusarium phaseoli and Macrophomina phaseoli compared t o non - treated seeds . Variety Wairimu dwarf had lower incidence of both root rot and common bacterial blight compared to Rosecoco (GLP 2). Seed treatment also resulted in significant increase in grain yield. The study showed that the low bean yields among t he small scale farmers in Maragua sub - county can be attributed to the prevalent use of u ncertified farm - saved bean seed and low usage of farm inputs such as pesticides and fertilizers. The farm - saved seed was of low quality resulting in low germination, po or crop stand, increased incidence of diseases and low yields. However, seed treatment can effectively manage root rot and foliar diseases and therefore, improve yields.