Degradation dynamics, correlations, and residues of carfentrazone-ethyl, fenoxaprop-p-ethyl, and pinoxaden under the continuous application in the wheat field.

Abstract

Weed infestation is a major biotic limitations in wheat cultivation; thus, various herbicides are being applied to control these weeds. Therefore, this study was undertaken for two successive years to assess degradation behaviours, persistence and residue risk imposed by carfentrazone, fenoxaprop-p-ethyl and pinoxaden sprayed as post-emergence herbicides in the wheat crop for management of weeds. Soil and crop samples were collected at periodically at after two hour of herbicide application till harvest of wheat crop and analysed by a high-performance liquid chromatograph. Degradation of carfentrazone, pinoxaden and fenoxaprop-p-ethyl, in the soil of wheat field occurred rapid to moderately with the mean half-life 9.92, 11.7 and 11.8days, respectively. Persistence was found to be dependent on the weather parameters as well as physicochemical properties of the soil and herbicides. Half-life of studied herbicides was found to be negatively correlated with persistence (R2 0.38, p = 0.05, n = 3) and vapour pressure (R2 0.99, p = 0.05, n = 3). Principal component analysis revealed that the first two Principal Components (PCs) had eigenvalues more than 1, and the first and second PCs contributed 77.4 and 22.6% in herbicide residues and different parameters variation, respectively. Terminal residues of carfentrazone, pinoxaden and fenoxaprop-p-ethyl in the wheat straw, grains and soil were found below the maximum residue limits. Owing to the moderate persistence under wheat field conditions, carfentrazone, pinoxaden and fenoxaprop-p-ethyl are supposed to be safe for control of weeds in wheat crop and hence, suspected risk on the human and environment or crop produce under evaluated doses is negligible.