Productive orcharding, modern methods of growing and marketing fruit . dplum. DISEASES OF POME FRUITS Scab.—This list may be very appropriately headed by thescab or black-spot, which stands in about the same relation toapple diseases as the codling moth does to apple insects. Itattacks fruit (Fig. 71), leaves and twigs. On the fruit it 166 DISEASES OF FRUIT TREES produces very characteristic spots which are a peculiar olivegreen in the early stages but soon become blackened, the skinusually breaking about the margins of the spot. In very badcases the spots coalesce and the fruit may crack open
Productive orcharding, modern methods of growing and marketing fruit . dplum. DISEASES OF POME FRUITS Scab.—This list may be very appropriately headed by thescab or black-spot, which stands in about the same relation toapple diseases as the codling moth does to apple insects. Itattacks fruit (Fig. 71), leaves and twigs. On the fruit it 166 DISEASES OF FRUIT TREES produces very characteristic spots which are a peculiar olivegreen in the early stages but soon become blackened, the skinusually breaking about the margins of the spot. In very badcases the spots coalesce and the fruit may crack open nearly tothe core (see Fig. 90). On the leaves the spots are usuallynearly circular in outline, at least in the beginning, and are ofa peculiar light green color which gradually changes to brownas the tissues die. In many cases the leaves wrinkle in a peculiarmanner, due to the growth of the surface being retarded irregu-larly. The scab passes the winter upon the old leaves in theorchard and the spores reinfest the trees the following springfrom these old Fig. 71.—Scab, or black-spot of the apple. This 13 the most serious of all the apple diseases,but can be controlled by thorough spraying. Susceptibility to Scab.—There is a very marked difference inthe relative susceptibility of different varieties of both pears andapples. Among pears the Flemish Beauty is peculiarly liableto attack and the crop is frequently ruined, many specimensbeing cracked nearly to the core, while adjoining trees ofBartlett may be relatively little affected. With apples theFameuse, Rhode Island Greening, Mcintosh and Spy are amongthose which are especially subject to attack. The treatment for scab, in either pears or apples, consistsin spraying with lime-sulfur or Bordeaux mixture, and thenumber of applications varies with the locality, the season andthe variety. If a bad attack is expected the trees should besprayed before the blossoms open, just after they fall and once BLOTCH 167 or tw
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