. Diseases of economic plants. Plant diseases. TREES AND TIMBER 449 causes a stoppage of the water supply to the more distant portions of the leaf, resulting in dead areas. Dead twigs should be pruned out, and infected material col- lected and burned. Spraying with Bordeaux mixture may be practiced if the expense is warranted. Powdery mildew. See oak. BLACK WALNUT Anthracnose, Gnomoniose {Marsonia jnglandis (Lib.) Sacc. of Gnomonia leptostyla (Fries) Ces. & d. Not.).—Con- spicuous brown spots, 2-4 mm. in diameter, appear upon the leaflets, which soon yellow and fall. Upon the lower sides o
. Diseases of economic plants. Plant diseases. TREES AND TIMBER 449 causes a stoppage of the water supply to the more distant portions of the leaf, resulting in dead areas. Dead twigs should be pruned out, and infected material col- lected and burned. Spraying with Bordeaux mixture may be practiced if the expense is warranted. Powdery mildew. See oak. BLACK WALNUT Anthracnose, Gnomoniose {Marsonia jnglandis (Lib.) Sacc. of Gnomonia leptostyla (Fries) Ces. & d. Not.).—Con- spicuous brown spots, 2-4 mm. in diameter, appear upon the leaflets, which soon yellow and fall. Upon the lower sides of the leaf spots are small, concentrically arranged, black acervuli. The disease has been trouble- some in Delaware, Iowa, Maryland, and West Virginia. WALNUT. ENGLISH Pseudomonose, blight (Pseu- domonas jnglandis Pierce^).— Up to the present time this disease has occurred only 1 Pierce, N. B., Bot. Gaz. 31, 273. 2g. Fig. 195. — Walnut twig blighted by bacteria. After R. E. 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, 1871-1934; Hall, John Galentine, 1870-. New York, Macmillan
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