. Diseases of economic plants. Plant diseases. Pomaceous Fruits 39 bordered with a narrow red line. In older cankers the diseased bark becomes cracked, furrowed, and much rough- ened. On the leaf this fungus causes small, regular, light brown, yellowish, or whitish spots, usually 1-2 mm. in diameter, each of which may bear one or several pycnidia. The Ben Davis, Missouri Pippin, Limber Twig, and Maiden Blush are highly sus- ceptible, while Winesap, Jona- than, and York Imperial are almost immune. Ordinarily three applica- tions of 3-4-50 Bordeaux mixture suffice to control blotch. The first sp
. Diseases of economic plants. Plant diseases. Pomaceous Fruits 39 bordered with a narrow red line. In older cankers the diseased bark becomes cracked, furrowed, and much rough- ened. On the leaf this fungus causes small, regular, light brown, yellowish, or whitish spots, usually 1-2 mm. in diameter, each of which may bear one or several pycnidia. The Ben Davis, Missouri Pippin, Limber Twig, and Maiden Blush are highly sus- ceptible, while Winesap, Jona- than, and York Imperial are almost immune. Ordinarily three applica- tions of 3-4-50 Bordeaux mixture suffice to control blotch. The first spraying should be made two or three weeks after the petals have fallen; the second about two weeks later; the third two weeks thereafter. Lime-sulfur should be substituted during wet weather to avoid Bor- deaux injury. Careful prun- ing to remove affected twigs is beneficial. Rusts ^^' ^^' ^^^ (Gymnospor- angium sps., Roestelia). — Rusts of the apple may usually be recognized by their char- acteristic spots on the leaf, or more rarely upon the fruit or twig. These spots, yellowish green at first, gradually become darker, approaching orange. Upon close examination, the upper surface of one of these discolored spots is seen to con- tain numerous pustules, at first honey yellow, finally black,. Fig. 15. — Apple leaf affected with rust. After 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 Stevens, Frank Lincoln, 1871- [from old catalog]; Hall, John Galentine, 1870- [from old catalog] joint author. New York, The Macmillan company
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyo, bookyear1921
