. Diseases of economic plants. Plant diseases. 418 Diseases of Economic Plants CHRYSANTHEMUM Leaf-spot ^•^•'' {Septoria chrysanthemella Cav.). — Large brown to black blotches, often irregularly circular and of indefinite border, appear upon the leaves. These enlarge and coalesce to involve the whole leaf, which withers, dies, and falls away. The lower leaves are first affected, but in later stages all the leaves of the plant may be badly spotted, and practically complete defoliation may result. Cuttings from infected stock should be avoided. All diseased foliage should be picked, collected, an
. Diseases of economic plants. Plant diseases. 418 Diseases of Economic Plants CHRYSANTHEMUM Leaf-spot ^•^•'' {Septoria chrysanthemella Cav.). — Large brown to black blotches, often irregularly circular and of indefinite border, appear upon the leaves. These enlarge and coalesce to involve the whole leaf, which withers, dies, and falls away. The lower leaves are first affected, but in later stages all the leaves of the plant may be badly spotted, and practically complete defoliation may result. Cuttings from infected stock should be avoided. All diseased foliage should be picked, collected, and burned, and the remaining foliage should be sprayed with Bordeaux mixture with addition of soap sufficient to form a suds to increase its adhesive power. Five or six sprayings during the season are usually sufficient. Leaf-spot (Phyllostida chrysanthemi E. & D.). — This disease, first described in 1893, is very similar to the above, ex- cept that the spots are more regularly circular, are purplish brown, and have a distinct border. Pycnidia which may often be seen with the naked eye are present. Wilt (Fusarium sp.) occurs occasionally. Rust ^^^ {Puccinia chrysan- themi Roze). — Apparently a na- tive of Japan, the rust was introduced into England (1895) and Europe through commercial agencies, and similarly into the Fig. 218. — Chrysanthemum United States, where it was first leaf shoeing rust son. Ong- ^^^^^ .^ ^^^^ .^ Massachusetts. It was rapidly spread throughout this country by diseased stock, and is now known in nearly all localities where the chrysanthemum is cultivated. 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 Stevens, Frank Lincoln, 1871-1934; Hall, John Galentine, 1870-. New York, Macmillan
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