. Manual of fruit diseases . Fruit. APPLE DISEASES 73 external evidence of the disease is the appearance of the char- acteristic sporophores of the parasite (Fig. 20) which grow out through knot-holes where branches have broken off (Fig. 21, right). These fruiting bodies are more or less hoof-shaped, hard, black, and checked on the upper surface (Fig. 20), and dark-brown and porous on the lower surface. The pores are extremely small, their diameters being not more than one-six- teenth of an inch. The size of the sporophores themselves varies greatly. The in- ternal symptoms of disease are evid
. Manual of fruit diseases . Fruit. APPLE DISEASES 73 external evidence of the disease is the appearance of the char- acteristic sporophores of the parasite (Fig. 20) which grow out through knot-holes where branches have broken off (Fig. 21, right). These fruiting bodies are more or less hoof-shaped, hard, black, and checked on the upper surface (Fig. 20), and dark-brown and porous on the lower surface. The pores are extremely small, their diameters being not more than one-six- teenth of an inch. The size of the sporophores themselves varies greatly. The in- ternal symptoms of disease are evident when the tree is cut or blown over. Cross sections of the diseased portion show symptoms quite distinctive of the trouble (Fig. 21). Affected trees never become hollow, but the rotten wood re- mains in place with a few cracks. The cen- tral area of the diseased heart is whitish or light- yellow (Fig. 21). Bor- dering this area is a narrow black line; sometimes there are several of these black lines arranged concentrically with white areas between them, and a yellowish to reddish brown zone, with an in- definite border, just outside the outermost black ring (Fig. 21). The character of the wood in these areas is as follows : — (1) in the white central area the wood is soft and crumbly when rubbed between the thumb and finger; (2) between the con- centric black lines it is similar to that in the center, except that decomposition has not progressed so far; (3) outside the outer-. FiG. 21. — White heart-rot; cross section of an affected limb showing the rotted heart- wood, the blaclc lines and at the right a young fruit-body of the 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
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1917
