. Manual of fruit diseases . Fruit. 338 MANUAL OF FRUIT DISEASES was observed several years ago that the Bosc, Sheldon, Seckel, Anjou, Bartlett and others are injured more than the Flemish, Clairgeau and Duchess. The Kieffer, Lawrence and Mount Vernon are relatively resistant to leaf-spot. In the nursery, budded pear-stock, after the first year, may show occasional lesions, but budded stock of two or more years is often badly injured late in the simamer. Symptovis. Only the leaves are affected. The mature spots are recog- nized by their well-defined angular margins and their grayish white cent
. Manual of fruit diseases . Fruit. 338 MANUAL OF FRUIT DISEASES was observed several years ago that the Bosc, Sheldon, Seckel, Anjou, Bartlett and others are injured more than the Flemish, Clairgeau and Duchess. The Kieffer, Lawrence and Mount Vernon are relatively resistant to leaf-spot. In the nursery, budded pear-stock, after the first year, may show occasional lesions, but budded stock of two or more years is often badly injured late in the simamer. Symptovis. Only the leaves are affected. The mature spots are recog- nized by their well-defined angular margins and their grayish white centers in which a few pyc- nidia develop (Fig. 93). They are found on the upper surface. The for- mation of a spot proceeds as follows. The affected tissue becomes brownish, which discoloration enlarges until the mature size of the spot is reached. These usually measure about one-sixth of an inch or less in diameter. The margin, while sharply defined, is angular and crenulate. With age the brown color at the center turns grayish white and becomes somewhat transparent. About this light-colored central area is a brown zone which merges into a purplish zone and finally into the healthy green portion of the leaf. Ordinarily lesions are not abundant, but under exceptionally favorable conditions numerous spots develop over the leaf-surface. Several may merge, involving large areas of Fig. 93. — Mycosphserella leaf-spot on 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
