1917] DISEASES OF PLANTS, X47 



very virulent stem and tuber rot. The organism appears to be related to, if 

 not identical with, F. eumartii. 



Crop yield, tuber color, and leaf roll of potato in relation to soil and 

 fertilizer, J. Ahr, O. Mayr, and Wokle {FiUiUng's Lanclw. Ztg., 64 U9i5), No. 

 17-lS, pp. 425-452, figs. 3). — Giving details and discussion of several series of 

 experiments dealing mainly with nutritive materials as affecting potato cul- 

 ture, the authors state, in reply to the statements of Schander (E. S. R., 33, 

 p. 433), that apparently without reference to the degree of maturity or the 

 kind of fertilizer, the dark colored tubers of the variety Wohltmann showed in 

 one year under the influence of given soil conditions a lighter color of skin 

 and a corresponding alteration in the growth of the plant, its resistance to 

 disease, and its productivity. Apparently, there is no connection between the 

 appearance of leaf roll and the coloration of the potato, the latter appearing 

 to depend principally upon the physical properties of the soil, which the ex- 

 periments show to be the preponderating influence in potato production. 



Field studies on the Rhizoctonia of the potato, M. T. Cook and H. C. Lint 

 {Ahs. in PhytopathoJogy, 6 (1916), No. 1, p. 106). — Rhizoctonia diseases of po- 

 tatoes are said to have been severe in New Jersey in 1915, the attack of the 

 fungus causing poor germination, brown stem, curly leaf, dwarfing, aerial 

 potatoes, and little potatoes, with resultant poor stands, reduced yields, and, 

 in some cases, complete loss of the crop. The results obtained from seed 

 treatment were variable, but corrosive sublimate proved much better than 

 formaldehyde for the prevention of these troubles. 



The effect of Bordeaux mixture on the potato plant, B. F. Lutman {Ahs. in 

 Phytopathology, 6 {1916), No. 1, p. 10'8). — Basing his conclusions on seven years' 

 investigations in this country and one in Germany, the author believes that the 

 beneficial effects of Bordeaux mixture can be ascribed to the prevention of the 

 early appearance of tipburn and of the greater part of flea beetle injury. Of 

 these two effects the former is considered the more important, as tipburn 

 advances much more slowly on sprayed than on unsprayed plants. The cause 

 of this retardation is thought to be some sort of chemical union between the 

 chlorophyll and the copper compounds. Sprayed plants unaffected by tipburn 

 are not found to produce more starch per plant than unsprayed ones. 



Biochemical study of root rot in sugar beets, J. Bodnab {Ztschr. Pflanzerv- 

 krank., 25 {1915), No. 6, pp. 321-325). — The substance of this report has been 

 noted i)reviously from another source (E. S. R., 34, p. 52). 



Fruit tree diseases of southern Ontario, W. A. McCubbin {Canada Expt. 

 Farms But. 24, 2. ser. {1915), pp. 77, figs. 70).— Popular accounts are given of 

 the diseases of fruit trees known to occur in Ontario. The fungi causing these 

 diseases are described and suggestions given for control measures. 



Temperature relations of apple rot fungi, C. Bkooks and J. S. Cooley {Abs. 

 in Phytopathology, 6 {1916), No. 1, p. iii ) .—According to the authors, apples 

 with natural infections of bitter rot and black rot were stored at various 

 temperatures. The development of bitter rot was slow at 15, rapid at 25, and 

 slow at 30° C. It was completely inhibited at 0, 5, and 10°, but developed 

 rapidly when the apples were removed to a temperature of 25°. 



Black rot developed rapidly at 25°, but it had made little progress at 10° 

 at the end of ten days. After two months' storage, there was considerable 

 development even at 0°. 



The temperature relations for growth of a number of other fungi occurring 

 on stored apples are also reported upon. 



Black root rot of apple, H. R. Fulton and R. O. Cromwell {Abs. in Phyto- 

 pathology, 6 {1916), No. 1, p. 110).— A form of root rot is briefly described, as 

 it has been observed as serious in a number of places in Pennsylvania and 



