This section is from the book "Commercial Gardening Vol3", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This disease is the cause of considerable loss both in this country and on the Continent. The symptoms are very marked, and cannot be confounded with those produced by any other known disease. The leaves that are attacked by the fungus during the summer remain hanging on the trees throughout the following winter, and after the next crop of leaves have appeared, which become infested in turn by spores produced on the old dead leaves. Hence when a tree is once infected the disease usually continues to appear each succeeding season. Trees that have suffered from the disease for several seasons make very little wood, owing to the leaves turning yellow and dying early in the season; the crop of fruit gradually decreases in quantity and quality, and eventually the tree dies. The fruit is also frequently attacked, when it either falls before maturity or becomes distorted and worthless. It must be clearly understood that the leaves and fruit are the only portions of the tree attacked by the disease, therefore if all such are removed no infection could take place the following season. This practice has been followed in Germany, where the disease is rampant, and with the most satisfactory results. After carefully removing all dead leaves during the winter for two consecutive seasons the disease was stamped out. Afterwards the trees recovered and produced fruit in abundance. It is, of course, more satisfactory, where a whole area is infected, that the clearing away of leaves should be general; but this is expecting the impossible. Yet, as the disease does not spread rapidly, it would well repay doing in a single orchard, even when surrounded by diseased ones.
Salmon has demonstrated that by spraying with Bordeaux mixture the disease can be held in check. Two thorough sprayings were applied, one just before the flowers opened, a second soon after the petals had fallen.
Very few dead leaves remained on the treated trees, which were nearly restored to health in a single season. Of course, so long as untreated trees are growing in the neighbourhood, the trees must be sprayed every season, and the fundamental cause of the disease remains untouched. This can only be exterminated by the removal of all dead hanging leaves, and burning them, throughout the entire district affected, and if looked upon in the light of an investment, time would prove it to be a very remunerative one.
Brown Rot (see p. 86) also attacks Cherries, and is best checked by spraying with Bordeaux mixture before the flowers open, and again just after the fruit has set. [g. m.]
There are two insects that stand out prominently as doing damage to cherries: The Winter Moth Caterpillar and the Cherry Aphis or Black Fly.