The Brown Rot disease so common on peaches and plums is also prevalent on apricots in those regions where this fruit is cultivated. It is regarded as a serious disease of the apricot in Europe, causing greater total damage abroad than in America on account of the more extensive apricot - culture in European countries. In the state of California, however, considerable damage is done to young twigs, which are wilted and killed back, and to fruits on the tree, which are rotted as in the case of peaches. Early apricots are said to suffer most, probably on account of moisture relations rather than because of any varietal peculiarities.
No definite schedule of control has been demonstrated, but it is recommended that self-boiled lime sulfur be applied (1) just as the fruit is setting, and (2) later, depending on the amount of rain. In seasons of brief shower-periods followed by drying weather, spraying is regarded as unnecessary. (Brown Rot is more fully discussed under Peach, page 270.)
Like other fruit-trees, the apricot suffers from the effects of frost. Injury by low temperatures in winter, winter injury, is perhaps the most destructive of all apricot troubles. Collar Rot, or crown rot, is particularly common and injurious. (For fuller discussion and additional references see under Apple, page 35.)