. Bulletin. Agriculture. April, 1912.] SOME APPLE DISEASES—TREATMENT. 17 BLACK ROT, CANKER AND LEAF SPOT. Sphoeropsis Malorum Berk. The three diseases given above have been found to be due to a single fungus, ^'Sphoeropsis ; The black rot of the apple is very common in New Hampshire. It is dark brown or black in color and the affected tissue comparatively firm. It is thus readily distinguished from the soft rots. It may start on any part of the fruit, but often begins at the blossom and fre- quently follows insect stings. The disease is primarily a rot of ripe fruit, but it may of
. Bulletin. Agriculture. April, 1912.] SOME APPLE DISEASES—TREATMENT. 17 BLACK ROT, CANKER AND LEAF SPOT. Sphoeropsis Malorum Berk. The three diseases given above have been found to be due to a single fungus, ^'Sphoeropsis ; The black rot of the apple is very common in New Hampshire. It is dark brown or black in color and the affected tissue comparatively firm. It is thus readily distinguished from the soft rots. It may start on any part of the fruit, but often begins at the blossom and fre- quently follows insect stings. The disease is primarily a rot of ripe fruit, but it may often be found as dark brown spots 1-8 to 1-2 inch in diameter several weeks before the apples are mature. These spots may develop very slowly until about picking time, but after that spread rapidly, in- volving the whole apple. As the rot develops, numerous minute, black elevations may be seen on the apple (Fig. 20). These are the spore producing bodies of the fungus and are known as pycnidia. The rot does considerable damage in cellar storage, but is especially common on the .fruit left on the trees or ground. This worthless fruit becomes a source of infection the following spring. Canker is a term applied to rough, unsightly wounds that are known to be due to the action of fungi. The most common variety of this trouble in New Hampshire is the "black rot canker," also known as the "New York apple tree ; ^ Both large and small limbs are attacked and sometimes the trunk. In some cases it seems to cause merely a greater roughening of the bark, but where a broken twig or other injury furnishes an entrance to the actively growing tissue of the host the effects. Fig. 20.—Black Rot of apple due to Sphoeropsis Mahriim. 1 Paddock, Wendell. The New York Apple-Tree Canker. N. Y. Agr. Exp. Sta. Bull. Paddock, Wendell, Ibid (Second Report), N. Y. Agr. Exp. Sta. Bull. Please note that these images are extracted from scanned page images that may hav
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