Penetration of bean leaves by aminotriazole as influenced by adjuvants and humidity

Abstract

AbstractPenetration of bean leaves (Phaseolus vulgaris var. Canadian Wonder) by aminotriazole (3‐amino‐1,2,4‐triazole) was greatly enhanced under high humidity conditions (ca 10% in 17 h at the low humidity level (LHL) compared with ca 80% in 2 h at the high humidity level (HHL)). The addition of polyoxyethylene 20 sorbitan monolaurate (polysorbate 20) to the spray fluid increased penetration on all occasions at the LHL. The increase obtained was found to be dependent on the concentration of polysorbate 20. The inclusion of polysorbate 20 at the HHL resulted in an increase in aminotriazole penetration at low polysorbate 20 concentrations 0.2–12.8 g/litre and a non‐significant decrease over the aqueous control at a concentration of 40 g/litre. With additions of glycerol to the spray fluid, aminotriazole penetration was increased on all occasions at the LHL while at the HHL no concentration of glycerol was found to enhance penetration. The addition of polysorbate 20 (< 0.1 to 40 g/litre) to a spray solution containing glycerol (0.3 ml/litre) enhanced penetration at the HHL compared with the aqueous and glycerol controls. A polysorbate 20 plus glycerol combination (6.4 g+0.6 ml/litre) gave the same order of penetration (98.4 and 94.0%) at the HHL and LHL respectively. In both cases penetration exceeded that obtained with the corresponding polysorbate 20 and glycerol controls. Some of the practical implications of these findings are discussed.