450 EXPERIMENT STATION RECORD. [Vol.41 



DISEASES OF PLANTS. 



Plant pathology to-day, C. L. Shear and N. E. Stev'ENs {Sei. Mo., 7 (1918), 

 No, 3, pp. 235-243). — This is a brief account, with illustrations, of the progress 

 of plant pathology as regai-ds aims, methods, accomplishments, limitations, re- 

 strictions, present tendencies, and opportunities for this work, and more par- 

 ticularly of the broader outlook of pathologists and of the general tendency 

 toward effective cooperation, both within and between States and Nations. 



Progress in control of plant diseases, R. E. Vaughan {Ann. Rpt. ^\'^s. State 

 Hort. Soc, J,8 {1918), pp. 179-186).— It is stated that by employment of sani- 

 tary measures, coupled with spraying, a number of diseases can be controlled, 

 though chief reliance is placed on the development of resistant plants. The 

 fungus causing cherry leaf spot was found (as is the case also with apple scab) 

 to overwinter on falling leaves. Angular leaf spot and anthracnose of cucumber 

 are controlled by seed treatment. Cucumber mosaic appears to be associated 

 with the presence of the striped cucumber beetle. Strains of kraut cabbage 

 resistant to yellows have been developed. Tobacco strains resistant to root rot 

 have also been obtained. Bordeaux mixture at a strength of 3 : 3 : 50 gives 

 control of cherry shot-hole leaf spot with only two applications if these are 

 timely and are combined with sanitary measures. 



[Plant diseases in South Africa, 1917—18], I. B. P. Evans {Union So. Africa 

 Dept. Agr. Rpt., 1917-18, pp. 65-68). — In this portion of the report on the divi- 

 sion of botany, the author gives brief notes on investigations carried out on 

 citrus canker, bacterial spot of citrus {Bacillus citrimaculans) , walnut blight 

 {Bacterium jnglandis) , bean blight {B. phaseoli, Pseudomonas sp.), sugar cane 

 root disease {Marasmius sp. ), cane leaf spot {Cercospora saccliari or Helinintho- 

 sporium sp.), papaw leaf spot {Phoma sp.) and fruit spit, and pineapple black 

 rot {Penicillum sp.), together with a list of papers issued during this period 

 on plant diseases. 



It is stated that a further outbreak of citrus canker was discovered at 

 Wolhuterskop near Rustenburg in June, 1917. Apparently the disease had been 

 present in one locality for 8 or 9 years, being traceable to nursery-stock, buds, 

 or cuttings. 



[Outgrowths on plants], T. A. C. Schoevees {Tijdselir. Plantensiekten, 24 

 {1918), Nos. 8, pp. 123-132; 4, pp. 133-148).— This is mainly a discussion of 

 known data on crown gall, with references to contributions on the subject. 



[Verticilliose] in cultivated crops, H. A. A. van der Lek {Tijdschr. Planten- 

 ziekten, 24 {1918), No. 3, pp. 81, 82). — A brief account is given of a study dur- 

 ing 1916-17 of verticilliose in cucumber, said to be identical with the disease 

 caused by VerticHUum alboutruni in potato and other plants. 



Clover stem rot, F. A. Wolf and R. O. Ckomwell {North Carolina Sta. Tech. 

 Bui. 16 {1919), pp. 5-18, pis. 3). — The presence in North Carolina of a stem rot 

 disease of crimson clover has led to a study of this disease, which is said to be 

 prevalent in Europe and rather widely distributed in the United States. The 

 disease is due to Sclerotinia trifoUorum and, in addition to the crimson clover, 

 the fungus attacks red clover, white clover, alsike clover, and alfalfa. The 

 disease prevails from October to March and may be recognized by the sudden 

 wilting and death of plants in spots, a rotting off or decay of the stem near the 

 ground, and the presence of black sclerotia on the decaying stems. 



A study was made of the development of /S. trifoUorum in comparison with 

 S. libertiana, and infection experiments were made with the different organisms. 

 Comparative morphological studies indicate that they are distinct species. The 

 sclerotia are said to remain dormant in infested .soils, and to be carried by con- 

 taminated seed as well as on implements, soil, hay, etc. It is recommended that 



