400 PATHOLOGY [Bot. Absts. 



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2751. Schander, R. Beobachtungen und Versuche iiber Kartoffeln und Kartoffelkrank- 

 heiten im Sommer 1917. [Observations and investigations of potato diseases in 1917.] Fiihl- 

 ing's Landw. Zeit. 67: 204-226. 1918. — Numerous tubers of the varieties Atlanta and Kaiser- 

 krone were attached by Phytophtkora infestans although stems and leaves were free. — Author 

 thinks late blight control should be sought primarily in development of disease resistant 

 varieties. [From abstract by 0. K[irchner] in Zeitschr. Pflanzenkr. 29: 118-119. 1919.] — 

 D. Reddick. 



2752. Schoyen, T. H. Beretning om skadeinsekter og plantesygdommer i landog have- 

 bruket 1917. [Report on insects and diseases of field and garden crops in 1917. | Aarber. 

 Landbr. Dept. [Norway] 1917: 29-101. 1918. — Brown leaf-spot of barley (Pleospora teres) 

 was very abundant on account of wet weather. — Potato wart (Synchitrium endobioticum) 

 has appeared in increasing abundance and regulatory mandates must be issued. — Gooseberry 

 mildew (S. mors-uvae) continues to spread. It occurs on black currant but rarely winters on 

 this host. — Rose mildew (Sphaerotheca pannosa) was not controlled by spraying with 0.4 per 

 cent formaldehyde solution. — The disease caused by Exobasidium azaleae can not be controlled 

 by use of lime-sulfur solution. The affected leaves must be picked off before the fungus 

 sporulates.— [From abstract by O. K[irchner] in Zeitschr. Pflanzenkr. 29: 107-108. 1919.] 

 — D. Reddick. 



2753. Schwartz, M. Ueber die Nachtschneckenplage 1916 in Nordfrankreich. |Plague 

 of slugs in northern France in 1916.] Zeitschr. Pilanzenkrankh. 29: 81-84. 1919. 



2754. Schoevers, T. H. C. De tomatenkanker, een voor Nederland ernstige tomaten- 

 ziekte. [Tomato canker: a serious disease in Holland.] Tijdschr. Plantenz. 25: 174-192. 

 PI. 8-5. 1919. — A canker disease of the stalks of tomatoes occurring both in the greenhouse 

 and in the field is described. Fruits are also affected especially about the stem end. inducing 

 a rot which causes them to drop. No lesions on leaves or petioles were discovered. A gird- 

 ling followed by a wilting of the parts above the stalk lesion is the most striking symptom. 

 Pycnidia of a species of Ascochyta develop abundantly on the cankered areas. This fungus 

 was obtained in pure culture and its causal relation established by controlled infection ex- 

 periments. Although the author obtained no perfect stage of the parasite, he believes it to 

 be identical with Ascochyta citrullina the perfect stage of which is known to be M j/cosphaer- 

 ella citrullina. The pathogene which has been destructive the past two seasons appears to 

 be widely distributed in Holland. It seems to have been but recently introduced, probably 

 from England. This disease may be mistaken for the wilt due to Verticillium alboatrum or 

 for the root rot caused by Rhizoctonia solani but is readily distinguished from either of these 

 upon critical examination of the symptoms. No satisfactory method of control has been 

 discovered. Sanitary measures are recommended. — //. //. Whetzel. 



2755. Schultz, E. S., Donald Folsom, F. Merrill Hildebrandt, and Lon A. Haw- 

 kins. Investigations on the mosaic disease of the Irish potato. Jour. Agric. Res. 17: 247-273. 

 PL A, B and 25-30. 1919.— Mosaic is widely distributed in the United States. Character- 

 istic symptoms, which appear on aerial parts only, may be modified or obscured by differences 

 in environment or of variety. Tubers of diseased plants transmit the disease. It is also 

 transmitted by diseased scions in grafting, by transfer of expressed juice from a diseased to 

 a healthy plant, and by at least 2 sucking insects, Myzus persicae and Macrosiphum solanifolii. 

 — Foliage of mosaic plants show a higher sugar content and lower starch content than that 

 from healthy plants.' -Tubers from plants showing mosaic may develop plants free from the 

 disease, or the progeny may show no ill effects of the disease, or, not uncommonly, the yield 

 is considerably decreased. — Hill selection alone is not a satisfactory means of control because 

 plants may become affected late in the season and slmw no symptoms of the disease although 

 the progeny shows that infection occurred. — Rogueing out diseased plants before the appear- 

 ance of mosaic transmitting insects has been found efficient in checking the spread of the 

 disease. — Ii. Reddick. 



