Pesticide Effects on the Plant Cuticle: IV. The Effect of EPTC on the Permeability of Cabbage, Bean, and Sugar Beet Cuticle1

Abstract

S-ethyl dipropylthiocarbamate (EPTC, 2.24 kg×ha) inhibited epicuticular wax production on developing leaves of cabbage ( Brassica oleracea L. Capitata group cv. Market Prize), resulting in an increase in cuticular permeability. This increased penetration of 14 C-I-naphthaleneacetic acid ( 14 C-NAA) and increased cuticular transpiration. EPTC-enhanced penetration was a consequence of increased diffusion across the cuticle, and not of active uptake. Application of EPTC increased penetration of NAA 200% in bean ( Phaseolus vulgaris L.)and 121% in sugar beet ( Beta vulgaris L.). For cabbage, the percent increase in penetration due to EPTC inhibition of cuticle development 7 days after treatment (141 %) was similar to that at 42 days (112%). The effect of EPTC declined until full leaf expansion (28 days after application). Silver nitrate was preferentially taken up by the cuticular ledges of guard cells and the anticlinal walls of epidermal cells, and was greater in leaves from EPTC-treated plants than in those from non-treated plants.