EROSION OF WAXES FROM LEAF SURFACES BY SIMULATED RAIN.

Effects of simulated rain on the epicuticular wax of glaucous leaves have been studied. Droplets (250 to 400 μm) travelling at low or medium velocity (0.25 to 5 m s-1 ) fractured the dendrites and tubes on leaves of Brassica spp., the tubes on Eucalyptus globulus Labillardere and the ribbons on the adaxial surfaces of Pisum sativum L. and Fragaria ananassa Duchesne. Rates of erosion for Brassica and E. globulus leaves were high during an initial application equivalent to 1 mm rainfall but declined markedly with extended exposure. In contrast, erosion from P. sativum and F. ananassa proceeded at a fairly uniform rate throughout the exposure period. The composition of the detached wax deposits was identical with that of the intact leaf wax for Brassica species but differed for the other species. The practical consequences of wax erosion of field crops are considered.