| dc.description.abstract | Pests are a major constraint to production of navy beans (Phaseolus vulgaris
L.) in Kenya. Farmers rely primarily on insecticides to control navy bean pests
and use one insecticide molecule over a long period of time, resulting in high
pesticide residues and ineffective control of aphids, beanfly, whiteflies and
bean flower thrips. Therefore, a study was conducted to determine the effect of
some of the pesticides used by bean farmers on populations of aphids, bean
stem maggot and thrips, and grain yield of navy beans. The experiment was
conducted in Kimbimbi, Mwea- Tebeere, Central Kenya for two seasons in
December 2009 - August 2010. Eight pesticides namely Monceren®
(imidachloprid), Gaucho® (imidachloprid), Actara® (thiamethoxam), Ogor®
(dimethoate), Neembecidine® (azadaractin), Karate® (lamdacyhalothrin),
Cruisor® (thiamethoxam), Thunder® (imidac1oprid) and a control treatment
(no pesticide was applied) were evaluated using navy bean variety Mexican
142. Total counts of aphids, bean stem maggot and thrips were recorded and
grain yield of navy beans determined. Actara, monceren, neem and dimethoate
significantly reduced the number of aphids in the first season while cruiser,
Gaucho, thunder and Karate had no effect. In the second season, Actara,
dimethoate and Karate significantly reduced the number of aphids. All the
pesticides, except neembecidine in the first season, significantly reduced the
number of bean stem maggots. Pesticides had no effect on the flower thrips in
both seasons. Actara, Thunder, Ogor and Karate significantly improved grain
yield while Neembezidine, Monceren, Cruiser and Gaucho had no effect. It is
advisable for farmers to use Thunder and Actara which are environmentfriendly
and have minimal residues on the seeds. | en_US |
