The volatilization of formulated ester, amine and K salt derivatives of phenoxyalkanoic herbicides: Evidence to connect herbicide activity with plant nutrient status of tomato (Lycopersicon esculentumMill) plants

Abstract

Controlled environment studies were conducted involving different vapour treatments applied to tomato plants using the herbicides 2,4-D iso-octyl ester/ioxynil, 2,4-D dimethyl amine salt and MCPA K salt. These indicated that the amine salt and MCPA were much less volatile than the ester formulation when the herbicide dilutions were applied to filter paper. The application of the herbicides to the leaves of young wheat plants resulted in a considerable increase in vapour activity (tomato bioassay) in the case of the ‘low-volatile’ 2,4-D dimethyl amine salt. This suggests that the surfaces of some plants may increase the volatilization of phenoxy herbicides. Chemical analysis of tomato plant tops showed that increases in tissue concentrations of N and K were concomitant with evidence of herbicide activity. All three herbicides investigated produced similar changes in chemical composition of the plants which coincided with altered growth responses and morphological symptoms of phytotoxicltynnn.