. Manual of fruit diseases . Fruit. 360 MANUAL OF FRUIT DISEASES ceeds to such an extent that the normal form of the limb is strikingly changed (Fig. 102). The newly forming knot can often be detected in the fall, when it appears as a slight swelling (Fig. 100). It is, however, more conspicuous in the spring; at this-time it enlarges and the bark is ruptured, thus ex- posing a yellowish surface (Fig. 101). This color does not prevail long, but the fungus grows to the ex- terior and thereon develops its sum- mer spores which give to the knot a velvety olivaceous appearance. These spores are dis
. Manual of fruit diseases . Fruit. 360 MANUAL OF FRUIT DISEASES ceeds to such an extent that the normal form of the limb is strikingly changed (Fig. 102). The newly forming knot can often be detected in the fall, when it appears as a slight swelling (Fig. 100). It is, however, more conspicuous in the spring; at this-time it enlarges and the bark is ruptured, thus ex- posing a yellowish surface (Fig. 101). This color does not prevail long, but the fungus grows to the ex- terior and thereon develops its sum- mer spores which give to the knot a velvety olivaceous appearance. These spores are dissemi- nated in April, May and June, being car- ried by the wind to suitable places for initiating a new knot. As the sea- son advances the gall gradually changes color; by the first of Sep- tember black dots appear over the surface, and within another month the whole knot is perfectly black and presents the appearance which is so commonly seen (Fig. 102). If one examines such a knot closely, it will be ob- served that it is then covered by innumerable small ele\'ations which project from its irregular surface (Fig. 102). Each of these elevations constitutes a winter condition of the fungus — a perithecium in which a second kind of spores develops from. Fig. 102. - Black-knot; two-year-old knots with black roughened Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hesler, L. R. (Lexemuel Ray); Whetzel, Herbert Hice, 1877-1944. New York : Macmillan
Size: 1488px × 1680px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1917
