Efficacy of potassium salts of fatty acides in the management of thrips and whiteflies on snapbeans

Abstract

Snap bean farmers mainly rely on chemical pesticides to manage insect pests and diseases but the introduction of strict maximum residue levels (MRLs) by European markets pose a challenge to the use of pesticides. This has necessitated the search for alternative pest management options that do 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 the management of snap bean pests. Field experiments were carried out in farmers’ fields in Mwea and Embu in 2013 for two cropping cycles. Potassium salts of fatty acids at 0.5%, 1% and 1.5% spray solution were applied weekly starting from three weeks after emergence (WAE) until early podding. The efficacy of the different concentrations was evaluated by assessing population of thrips, whitefly, and pest damaged pods, in addition to pod yield.. The application of potassium salts of fatty acids at 1% and 1.5% of spray solution significantly (P<0.05) reduced white fly and thrips populations by up to 61% and 69% respectively. Pod damage due to thrips was also significantly (P<0.05) reduced by up to 83% and marketable pod yield was significantly (P<0.05) increased by up to 151%. The results demonstrated that potassium salts of fatty acids are a viable alternative to synthetic chemical pesticides thereby enabling farmers to meet the strict European markets maximum residue level requirements.