DISEASES OF PLANTS. 245 



Classification of local rusts, J. P. Bennett (Missouri Sta. Bui. 131 (1915), 

 p. Ii69). — It is statetl that there have now been collected and Identified G7 

 species of rust occurring on 127 hosts obtained from 443 collections. It is 

 thought probable that there are still at least as many more species occurring in 

 Boone County that have not yet been collected. 



The relation between Puccinia graminis and host plants immune to its 

 attack, E. C. Stakman ( Ahs. in Pliytopathologij, Jf (1914), ^^o. 6, p. 400). — In 

 continuation of previous studies (E. S. E., 31. p. 146), the author states that in 

 many cases, both with cereals resistant to a biologic form of P. graminis and 

 wheats resistant in varying degrees to attacks of P. graminis tritici, varying 

 degrees of infection occurred. In some cases fairly large areas of the host 

 tissue were killed outright, in others the discolored portions indicating the 

 death of the host tissue were extremely small. In extreme cases no spots 

 whatever are visible to the naked eye. A histological study of the infection in 

 such cases indicates that small areas of the leaf, comprising sometimes only four 

 or five cells are killed and the fungus is then unable to develop further. In the 

 case of normal infection the killing of the cells by the hyphse does not seem to 

 occur. Whether or not hypersensitiveness of the host plant toward P. graminis, 

 which is unable to infect it. is a universal phenomenon is not yet determined. 



Grain smut infections and control, G. M. Reed (Missouri Sta. Bui. 131 

 (1915), p. 469). — In testing pure strains of wheat a wide range as regards sus- 

 ceptibilit5' to bunt. (Tiiletia foetcns) was observed. A high degree of efliciency 

 was indicated as regards the method of inoculation employed, which consisted 

 simply in dusting the seed with the dry spores of the fungus. Treadwell proved 

 to be less susceptible than Red Cross or Early Ripe. It has not yet been con- 

 clusively shown that late planting results in a high pQreentage of smut, but it 

 has been proved that a high degree of soil contamination with smut siiores 

 causes smut in the subsequent crop. 



The necessity for aimual seed treatment of seed oats for loose smut (Ustilago 

 Icevis) is indicated. A wide variation in susceptibility was noted, .some sup- 

 posedly resistant varieties proving to be otherwise. The common method of 

 treating seed oats with formalin (1 lb. to 40 gal. water) is said to be abso- 

 lutely effective in preventing the smut. 



A bacterial leaf-spot disease of celery, I. C. Jaggeb (A'bs. in Phytopathology . 

 4 (1914), ^0. 6, p. 395). — The author reports having had under observation in 

 central and western New York for the past five years an apparently undescribed 

 leaf spot of celery. It is said to occur very commonly in that region, but so 

 far only a few cases of noticeable injury to the crop have been observed. Spots 

 of a rusty brown color, irregular in outline, are formed on the leaves, from 

 which bacteria have been repeatedly isolated and characteristic spots reproduced 

 by inoculation. The bacterial siiots closely resemble those due to Septoria, 

 being distinguished by means of the pycnidia in the spots formed by the fungus. 



Downy mildew of cucumbers, G. E. Stone (Massachusetts Sta. Circ. 51 

 (1915). pp. 2, fig. i).— This is a revision of Circular 40 (E. S. R., 32, p. 342). 



The control of onion smut, G. E. Stone (Massachusetts Sta. Circ. 52 (1915), 

 pp. 4, figs. 4).— This is a revision of Circular 41 (E. S. R., 32, p. 342). 



Leaf spot and some fruit rots of peanut, F. A. Wolf (Afts. in Phytopathology, 

 "4 (1914), A'o. 6, p. 397). — The substance of this note has been previously given 

 (E. S. R., 32, p. 546). 



Effect of temperature on germination and growth of the common potato 

 scab organism, M. Shapovalov (U. S. Dept. Agr., .Jour. Agr. Research, 4 (1915), 

 No. 2, pp. 129-134, pl- 1, fig- !)■ — This is a brief account of studies on the 

 potato scab organism formerly known as Oospora scaMes, but recently claimed 

 by Lutman and Cunningham (E. S. R., 32, p. 546) to be identical with Actino- 



