Bulletin [Of Cornell University Agricultural Experiment Station] New York (State). Agricultural Experiment Station, Ithaca Volume 225-249 baixar o livro de graça

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 Excerpt: ...abundant and destructive in many orchards of the State It is caused by a fungus and is in most respects very different from the blight canker with which, nevertheless, it is frequently confused. The chief differences between the two are set forth in the following parallel columns: New York Apple Tree Canker. Caused by a fungus. Usually found on the main limbs of old trees. Diseased portion more or less swollen, cracked and roughened. ( Fig. 62.) Cankered surface Hack. Covered with minute black pimples--the fruit bodies of the fungus often not so evident in old cankers. (Fig. 62). Freshly cankered tissue dry. Cankers perennial, i. e., living over and spreading from year to year. Blight Canker. Caused by bacteria. Occurring most frequently 011 the body and limbs of young trees just coming into bearing. Diseased area sunken and smooth not cracked and checked. (Fig. 53.) Cankered surface brown. Not showing any pimples or fungtisJrutt bodies, except in old cankers that have been invaded by saprophytic forms. Freshly cankered tissue watery. A large per cent of the cankers active but one season. 3. How The Disease Affects The Tree. The effect of the canker on the tree is to lower its vitality to a greater or less degree by cutting off the food supply to the roots, and thus indirectly reducing the flow of sap to the branches and leaves. In other words, it acts the same as partial or complete "girdling." The "collar rot " and "crotch cankers " seem to be the most fatal to the tree. The effects of the canker are first evidenced in the foliage. If there is a large body canker, the entire tree may show the effects of the trouble. More often the first symptom noted by the grower is the peculiar appearance of the foliage on one or more of th...