848 EXPERIMENT STATION RECOED. [Vol.35 



the possible origin of P. phleipratensis, which is considered as being probably a 

 biological species. 



Treatment of apple canker diseases, J. C. Whitten {Missouri Sta. Bui. I4I 

 (1916), pp. 33, 3^). — A brief account is given of experiments for the control of 

 apple canker disease. The diseased tissue was cut out until a rim of healthy 

 tissue was reached, and the area disinfected or treated with mercuric chlorid, 

 copper sulphate, iron sulphate, and paint. 



The mercuric chlorid treatment proved the most efficient. It is claimed that 

 canker can be largely eradicated from resistant varieties if treatment is given 

 before a large area is involved. When once the disease has become deep-seated 

 in susceptible varieties, the treatment will not stop it. 



Stippen and spray injury, C. H. Ceabill and H. E. Thomas {Phytopathology, 

 6 {1916), No. 1, pp. 51-54). — Attention is called to the various agents that have 

 been regarded as causing apple fruit spot, or stippen. Among those mentioned 

 are physiological disturbances, various pathogenic fungi, spray injury, me- 

 chanical injury, etc. 



As a result of the authors' investigations, it is claimed that stippen, or stippen- 

 like spots, that is, depressed, highly colored areas underlaid by a corky mass of 

 dead, brown cells, may be produced in several ways, as by bruising, insect punc- 

 ture, injected poisons, insufficient water, or any other agent which may kill a 

 few cells before the apple is full grown. The authors consider that the disease 

 is not caused by spray materials as they are commonly applied. 



The Phytophthora rot of apples, H. H. Whetzel and J. Rosenbaum (Phyto- 

 pathology, 6 (1916), No. 1, pp. 89, 90).— The authors report the presence on 

 Oldenburg apples, in July, 1915, of peculiar brown lesions. A Phytophthora was 

 isolated from these, which, on comparison, is believed to be P. cactorum. During 

 October and November the same fungus was again isolated from apples pur- 

 chased in the market of Ithaca, N. Y. While some investigators in Europe have 

 considered the fungus as quite destructive, the authors do not think that it will 

 occasion much injury in this country. 



New or noteworthy facts concerning apple rust, N. J. Giddings and A. Bebg 

 (Phytopathology, 6 (1916), No. 1, pp. 79, SO).— In continuation of investigations 

 (E. S. R., 35, p. 49), the authors present some of the more important facts 

 brought out in connection with the work on the apple rust fungus (Gymnos- 

 porangium juniperi-virginiance) . 



In addition to other statements, the authors claim that a severe infection of 

 the apple rust fungus may cause a premature loss of foliage, a decrease in size 

 of the fruit, and a diminution in the vigor of the tree. As a means of control, 

 the destruction of all cedar trees within a radius of I mile around apple orchards 

 has been recommended, but from the authors' observations it is now claimed 

 that this should be done within a radius of 1 mile. 



Some new facts concerning fire blight, P. D. Heald (Better Fruit, 10 (1916), 

 N08. 11, pp. 21, 22; 12, pp. 23-25; Kpt. Wash. State Hort. Assoc, 12 (1915), pp. 

 Sl-35, fig. i).— In amplification of a statement (E. S. R., 34, p. 647) regarding 

 new phases of attack by Bacillus amylovorus, the cause of blossom, twig, fruit, 

 and body blight of malaceous fruit trees, the author describes fire blight of a 

 characteristic type on developing fruits of apple. 



This type differs from that due to invasion of the fruit by way of the pedicel 

 (in which the whole fruit is destroyed) inasmuch as the localized, dark, de- 

 pressed, and sometimes red-bordered lesions do not always extend their area, 

 even under most favorable circumstances. Culture studies showed that many 

 of the bacteria were dead in these fruit spots. While insect punctures doubtless 

 afford entrance in some cases, in others invasions of stomata or lenticels may 



