Watching helplessly as a fungus starts to take over your orchard can be a frustrating, even heartbreaking, experience—whether you have two trees or two hundred.
Apple scab is a fairly common blight. Even professional apple growers have to deal with it. What do you do when you see those telltale little round greenish spots? Barbara Damrosch has some words of advice.
From the Washington Post:
It is a tale of two trees, one happy, one sad. Both of the crab apples in my garden are laden with white flowers in spring, bear red berries that last into the winter, for the birds’ pleasure, and sport yellow leaves in fall. But one of the trees sports them all too soon, in summer, when the scab fungus catches up with them. Its berries are sparse. The other tree is a vigorous grower with nary a sign of disease. The two are growing in identical plots, with well-amended soil.
Over in the orchard, where the eating apples are, scab is also in evidence. There, the focus is on the fruits. (Sure, you can make jelly from crab apple fruits, but the tiny size of most of those grown for ornament make them fussy to pick.) The Winesaps in particular have exhibited the telltale signs: little round greenish spots that have darkened into the eponymous scabs, as if they were just recovering from chicken pox. The Golden and Roxbury Russets, on the other hand, are largely unblemished, by scab or anything else.
Scab is a very common disease among apple trees. It’s a fungus that attacks in spring, does its work, then overwinters in the leaves and fruits that are shed in fall, until spring rains disperse the spores again. For clear, detailed information about apple scab, consult “The Apple Grower,” by Michael Phillips (Chelsea Green, $40).