Diseases of economic plants (1910) Diseases of economic plants diseasesofeconom02stev Year: 1910 TBEES 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 juglandis (Lib.) Sacc. of Gnomonia juglandis). — Conspicuous brown spots, 2-4 mm. in diameter, appear upon the leaflets, which soon yellow and fall
Diseases of economic plants (1910) Diseases of economic plants diseasesofeconom02stev Year: 1910 TBEES 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 juglandis (Lib.) Sacc. of Gnomonia juglandis). — Conspicuous 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 ar- ranged, black acervuli. The disease has been trouble- some in Delaware, Iowa, Mary- land, and West Virginia. WALNUT, ENGLISH Pseudomonose, blight (Pseu- domonas juglandis Piercel). — 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. Smith.
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