varieties. Prune the trees so as to let in sunlight and air. Thin the fruit well. As often as possible pick and destroy all rotten fruits. In the fall destroy all remaining fruits. Spray with bordeaux mixture before the buds break, or self-boiled lime-sulfur.
Leaf-curl is a disease in which the leaves become swollen and distorted in spring and drop during June and July (Fig. 213). Elberta is an especially susceptible variety. Easily and completely controlled by spraying the trees once, before the buds swell, with bordeaux, 5-5-50, or with the lime-sulfur mixtures used for San Jos scale.
Black-spot or scab often proves troublesome in wet seasons and particularly in damp or sheltered situations. While this disease attacks the twigs and leaves, it is most conspicuous and injurious on the fruit, where it appears as dark spots or blotches. In severe attacks the fruit cracks. In the treatment of this disease it is of prime importance _to secure a free circulation of air_ about the fruit. Accomplish this by avoiding low sites, by pruning, and by removal of windbreaks. Spray as for leaf-curl and follow with two applications of potassium sulfide, 1 oz. to 3 gal., the first being made soon after the fruit is set and the second when the fruit is half grown.
Yellows is a so-called "physiological disease." Cause unknown. Contagious, and serious in some localities. Known by the premature ripening of the fruit, by red streaks and spots in the flesh, and by the peculiar clusters of sickly, yellowish shoots that appear on the limbs here and there (Fig. 215). Dig out and burn diseased trees as soon as discovered.