| Abstract: | In field trials against apple scab (caused by Venturia inaequalis) and powdery mildew (caused by Podosphaera leucotricha), improved control of one or other disease has been given by the newer systemic fungicides benomyl, triarimol and the thiophanates. However, in tests on apple seedlings in the greenhouse, biological evidence of translocation from individual deposits was generally limited to movement within the treated leaf. In greenhouse tests with cucumbers and marrows, using Oidium sp., there was again little evidence for movement of toxicant from a treated leaf, although effective disease control was readily obtained by root application of several compounds at low dosage. These results suggest that the systemic properties of the compounds evident when used as soil or seed treatments are of little account when they are applied as foliar sprays. |
