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

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.