THE EFFECTS OF OIL-BASED FUNGICIDES ON WATER-LOSS OF COLEUS-BLUMEI LEAVES AND PELARGONIUM HYBRID PETALS

Effects of oil-based fungicides on plant surfaces were studied by assessing water loss from excised sprayed leaves or petals and by microscopy. Two fungicides (Turbair Zineb Fungicide and Turbair Copper Fungicide) were sprayed, using a Potter tower, onto the adaxial surfaces of excised leaves or petals, and weight loss was determined as a measure of water loss. Doses of approximately 4-9 g m-2 significantly increased water loss from Pelargonium hybrid petals and leaves of Coleus blumei Benth. The fungicides, their supernatants and the carrier oil increased water loss from the petals but effects of the supernatants and the carrier oil on C. blumei leaves were less conclusive. Low Temperature Scanning Electron Microscopy (LTSEM) did not reveal any scoring or marked erosion of the adaxial surface of leaves or petals 24 h after application of the fungicides. © 1990 Annals of Botany Company.