654 EXPERIMENT STATION RECORD. [Vol. 37 



tologlcal studies in all stages of the progress of the disease show the presence 

 of Rhizoctonia, and pure cultures of the fungus have been repeatedly obtained 

 from the interior of the diseased areas. Evidence is presented that indicates 

 that the host cells die and lose their contents and the walls suberize and are 

 more or less broken down in advance of the fungus filaments. This, the author 

 states, might lead to the supposition that part of the action is due to a toxin 

 secreted by the fungus. Cell wall penetration by the hyphae is thought to 

 occur, but this is believed to be the exception rather than the rule. 



A new strain of Ehizoctonia solani on the potato, .J. RosENBAUii and M. 

 Shapovalov (T. S. Dept. Agr.. Jour. Agr. Research, 9 (1917), Xo. 12, pp. 413- 

 420, pis. 2, figs. 3). — ^A description is given of a strain of R. solani which was 

 isolated from the stems of potatoes in ilaine during the summer of 1916. 

 This strain is distinguished from the more common form of R. solani by the 

 more pronounced lesions produced when inoculated on injured stems or tubers ; 

 by the reaction, growth, and charr.cter of sclerotia on definite media; and, 

 moi-phologically, by raeasurenieuts of the mycelium, also of the short sclerotial 

 cells, and by the measurement of the diameter of germ tubes when the short, or 

 barrel-shaped, cells enveloping the sclerotia are placed in drops of water to 

 germinate. 



An investigation of the potato rot occurring in Ontario during 1915, 

 D. H. .Tones (Abs. Bact., 1 (1917), Xo. 1, pp. 37, SS).— Reporting briefly the re- 

 sult of studies made during 1915 and 1916, the author states that potato diseases 

 are greatly favored by such continued wet weather as prevailed during 1915. 

 Rhizoctonia was the principal and soft rot bacillus the .secondary cause of the 

 black basal stem rot and collapse which occurred in many places during 1915. 

 the organism producing only a slightly shrunken, brown canker where the 

 cortical tissue alone was punctured. The soft rot bacillus could not penetrate 

 healthy, unbroken epidermal tissue, but when introduced beneath the punctured 

 epidermis of a young potato stem or tuber, or of carrot, turnip, or cauliflower, 

 it produced a characteristic soft rot. Seed tubers showing sclerotia of 

 Rhizoctonia (black scab) are most likely to give a diseased crop unless 

 disinfected, which may be done by soaking them in water for two or three 

 hours and then in 0.1 per cent corrosive sublimate for five or six hours. 



Fusariiim sp. caused much of the tuber rot observed at harvesting time and 

 in storage. The disease may be carried over in debris of the potato crop left 

 in the soil, high humidity favoring its development. 



Diseases of tomatoes, M. T. Cook and W. H. Martin (New Jersey Stas. 

 Cite. 71 (1917). pp. 8, figs. 6). — The authors briefly describe the more prevalent 

 fungus, bacterial, and other diseases of tomatoes, and offer suggestions for 

 their control. 



Apple blotch and its control, J. W. Roberts (U. S. Dept. Agr. Bui. 55-} 

 (1917), pp. 11, pis. 2, figs. 3). — The author describes the blotch of fruit, foliage, 

 and twigs of the apple due to the fungus Phyllosticta solitaria, and gives the 

 results of his investigations on the disease and on methods of control. His 

 cross-inoculation experiments are said to confirm the inoculation work of 

 Scott and Rorer (E. S. U., 20. p. 1044). 



As an explanation for the few infections which occur late in the season, the 

 author suggests an increased resistance of the host as well as a gradual de- 

 crease in the number of spores produced by the fungus. A large number of 

 mummied fruits were examined throughout the spring but no spores were 

 found, and hence the author concludes that mummies are not an important 

 source of infection. 



It is claimed that apple blotch may be controlled by three sprayings with 

 3 :4 : 50 Bordeaux mixture applied at intervals of three weeks, the first spray 



