172 



DISEASES OF FRUIT TREES 



In any case care should be taken not to spray these fruits, 

 especially peaches, so late that the spray will still be on them 

 at picking time. 



Peach Scab. This is a very common disease on many 

 varieties of peaches, producing small, blackish spots which may 

 be so plentiful as to make practically one whole side of the fruit 

 black. The growth of the side attacked is retarded so that the 

 fruit becomes one sided, and in bad cases this side frequently 

 cracks open. Fortunately the treatment just outlined for the 

 brown rot will also entirely check the peach scab. 



FIG. 73. Black-knot of the plum, showing how new knots will start from the old stubs 

 when these are not cut back far enough. 



Leaf Curl. This is a very striking disease and one which it 

 is very easy to recognize. It attacks all parts of the tree, 

 leaves, branches, flowers and fruit, but is so inconspicuous on 

 all parts but the leaves that it usually escapes notice. The leaves 

 thicken, curl up, and are often highly colored in certain parts 

 and in others of a light yellowish green. As the disease advances 

 the leaves turn brown and soon fall, causing a severe loss of 

 vitality to the tree, which not only loses the food which the leaves 

 would have produced had they remained healthy, but also is 

 further exhausted by being obliged to put on this second crop 

 of leaves. The spores of the disease live over winter on the 

 bark and gain entrance to the buds when growth starts in the 



