Spraying Fruit Trees
Most plants are subject to a variety of pests and diseases and some require routine spraying to keep them clean and in good health. However, at least one of the worst diseases of apples and pears, scab, is far less likely to prove troublesome in gardens situated in areas where there is considerable smoke since the sulphur left in the air acts as a kind of permanent mild fumigation, killing the spores of the scab disease before they have time to do much harm. Three-Period Programme Broadly speaking the spray programme for fruit trees and bushes divides into three periods. In winter, when there are no leaves on the trees, winter washes such as tar-oil or DNOC are applied to clean the bark and to kill the eggs of insects. Then, in the spring, fungicides are applied to kill the spores of various diseases and sometimes insecticides are added to these to kill any early caterpillars that have escaped the winter spray. Finally, in summer, insecticides are applied several times to deal with particular pests which appear at specific times, and further periodic spraying with fungicides may be necessary to control diseases such as scab and mildew.