19191 DISEASES OF PLANTS. 49 



has been in progress during tlie year. A list is given of liie most common dis- 

 eases tliat weTe observed during tlie year. 



The control of plant diseases due to fungi in Great Britain, A. S. Horne 

 {Jour. Roy. Hort. Soc, 42 {1916), No. 1, pp. 13-26, pis. ^).— This is a review of 

 studies, requirements, and measures related to plant diseases in Great Britain 

 and some other countries. 



Investigations [on plant diseases] at the National Fruit and Cider Insti- 

 tute {Jour. Bd. Agr. [London], 25 {1918), No. S, pp. S16-320).— Thin is a sum- 

 mary of portions of the work done during the year ended September 30, 1917, 

 in connection with plant diseases and injuries. Portions of this work as re- 

 ported by Barker and Bastin (E. S. R., 40, pp. 844, 847), have been noted. 



Phytopathological report, 1916 and 1917, P. Maechal and G. Arnaud {Min. 

 Agr. [France], Ann. Serv. Eplphyties, 5 {1916-11), pp. 6, 7, 20-35).— In this 

 portion of the general report of the Phytopathological Station of Paris are 

 noted the recent outbreak or extension of black canker of chestnut, American 

 gooseberry mildew {Spierotheca mors uvw), and black rot of grapes. A some- 

 what systematic account is given also of injurious agents affecting plants of 

 different classes, chiefly during the period under discussion. 



Summary reports of entomological and pathological laboratories {Min. 

 Agr. [F'rance], Ann. Serv. Epiphyties, 5 {1916-17), pp. 253-272). — This report 

 deals mainly with activities of the years 1916 and 1917 connected with injury 

 by insects and fungi as reported from stations dealing with entomology or 

 plant pathology or both, at Paris, Blois, Bordeaux, Montpellier, Saint-Genis- 

 Laval, and Cadillac (Gironde). Lists of related contributions are also given. 



The disinfection of the soil, B. MifiGE {Ulin. Agr. [France], Ann. Serv. Epi- 

 phyties, 5 {1916-17). pp. 83-114, figs. S).— The present contribution (E. S. R., 

 28, p. G23 ; 3G, p. 623) deals with soil treatments to increase fertility and to 

 give control of plant diseases attacking by way of the soil. 



Gum formation with special reference to cankers and decays of woody 

 plants, B. B. Higgins {Georgia Sta. Bui. 127 {1919), pp. 23-59, figs. 17).— In a 

 previous publication (E. S. R., 34, p. 747), the author suggested that gummosis 

 was probably caused by the action of an enzym, and as an enzym is usually 

 found in freshly formed gum the author carried on a series of experiments in 

 the artificial production of gummosis under partially controlled conditions. 



It was found that gum formation, although affected to some extent by varia- 

 tions in temperature, moisture, etc., is not dependent upon or always associated 

 with growth activity. This behavior, together with the fact that a pectin-dis- 

 solving enzym is always found in freshly exuded gum, is held to indicate that 

 gum formation is brought about by enzym activity. 



Studies on the crown rust of oats, I. E. Melhus and L. W. Durrell {loica 

 Sta. Research Bui. 49 {1919), pp. 115-144, figs. 6).— The data presented in this 

 bulletin, obtained in cooperation with the Bureau of Plant Industry of the 

 U. S. Department of Agriculture, constitute a progress report dealing largely 

 with the factors influencing the growth and reaction of crown rust {Puccinia 

 coronata) of oats and different species of Rhamnus, the data having been 

 accumulated during a period of three years. The temperature relations and 

 the moisture requirements of the uredospores were investigated. 



It was found that the minimum temperature for the germination of the 

 uredospores of crown rust is 1" C, the optimum 17 to 22°, and the maximum 

 35" (95° F. ). Direct contact with water is essential for the germination of 

 the crown rust uredospores, a saturated atmosphere not furnishing sufficient 

 moisture for germination. The environment under which the uredospores 

 were produced is said to influence their germination to some degree, spores 



