Efficacy of Potassium Salts of Fatty Acids in the Management of Thrips and Whitefly on Snap Beans

Geoffrey Ongoya Wafula,George N Chemining’Wa,John H Nderitu,James W Muthomi

doi:10.5539/sar.v6n4p45

Geoffrey Ongoya Wafula, George N Chemining’Wa + Show 2 more

Open Access

https://doi.org/10.5539/sar.v6n4p45

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Journal: Sustainable Agriculture Research	Publication Date: Aug 5, 2017
Citations: 9	License type: CC BY 4.0

Affiliation: University of Nairobi

Abstract

Snap bean farmers mainly rely on chemical pesticides to manage insect pests but the introduction of strict maximum residue levels (MRLs) by European markets poses a challenge to the use of pesticides. This has necessitated the search for alternative pest management options that do not result in harmful residues on produce. Therefore, this study was carried out to determine the efficacy of potassium salts of fatty acids as alternative to synthetic chemicals in management of snap bean pests. Field experiments were carried out in farmers’ fields in Mwea and Embu for two cropping cycles between July 2013 and January 2014. Potassium salts of fatty acids at 0.5%, 1% and 1.5% spray solution was compared with chemical pesticide confidor® (Imidacloprid) and farmers practice [Thunder® (Imidacloprid + Betacyfluthrin) and Karate® (Lambda Cyhalothrin). Population of thrips, whitefly, and yield of pest damaged pods, in addition to marketable pod yield was determined. Application of potassium salts of fatty acids at 1% and 1.5% significantly (P<0.05) reduced white fly and thrips populations by up to 54%. Weight of pest damaged pods was also significantly (P<0.05) reduced by up to 76% while the weight of marketable pod yield was significantly (P<0.05) increased by up to 112%. The results demonstrated that potassium salts of fatty acids are a viable alternative to synthetic chemical pesticides thereby enabling farmers to produce with acceptable residue levels that meet market requirements.

Highlights

Snap bean (Phaseolus vulgaris L.) is grown for the immature green pods primarily for export market to European Union and elite local urban markets (Infonet-Biovision, 2014)
The results demonstrated that potassium salts of fatty acids are a viable alternative to synthetic chemical pesticides thereby enabling farmers to produce with acceptable residue levels that meet market requirements
Potassium salts of fatty acids at 1.5% concentration significantly (P< 0.05) reduced whitefly population and was effective in the management of whitefly causing up to 65% reduction in whitefly population

Summary

Introduction

Snap bean (Phaseolus vulgaris L.) is grown for the immature green pods primarily for export market to European Union and elite local urban markets (Infonet-Biovision, 2014). The production of snap beans, one of Kenya’s most important export vegetable crops, is steadily rising (HCDA, 2014). Local consumption of Snap beans has increased over the last few years, providing a domestic market (HCDA, 2013). Snap bean production is mainly by small scale farmers and it is estimated that over 50,000 smallholder families are involved in snap bean production in Kenya contributing to the larger agricultural sector (Infonet-Biovision, 2014). The agricultural sector plays an important role in Kenya’s economy contributing directly and indirectly to the countries GDP by upto 24% and 27% in the year 2011 (MOA, 2012). Production of snap beans in Kenya is constrained by pests which include thrips (Frankliniella spp. and Megalurotrhips sjostedti), whiteflies (Bemisia tabaci and Trialeurodes vaporariorum), bean flies (Ophiomyia spp) and aphids (Aphis fabae) (Monda et al, 2003; Nderitu et al, 2007)

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Results

Conclusion