1"1f>] DISEASES OF PLANTS. 249 



B. serrata, method of tapping, effect of tapping on the tree, cost of extrac- 

 tion, and outturn. The succeeding parts comprise a chemical study of the gum- 

 oleo-resln and its constituents, together with recommendations relative to a 

 proposed experimental plant, methods of extraction, and preparation of the 

 products for market. Information is also given relative to the industrial uses 

 of the products and their commercial valuation, as determined hy the Imperial 

 Institute at London and a number of firms to which samples were submitted. 



DISEASES OF PLANTS. 



Botany and plant diseases, H. H. Whetzel (West. N. 7. Hort. Soc. Pror., 

 63 (1918), pp. 6S-71). — This is a report with discussion of plant diseases con- 

 sidered important to fruit growers in New York State. It includes apple scab, 

 stippin, and black root rot; cherry-leaf blight (shot hole or yellow leaf) ; peach 

 brown rot, scab, and leaf curl ; and gumming of plum fruits. 



Some meliolicolous parasites and commensals from Porto Rico, F. L. 

 Stevens (Bot. Gaz., 65 (1918), No. 3, pp. 227-249, pis. 2, figs. 5).— An account is 

 given of about 50 Meliolas and of the fungi found associated with each as 

 parasites or commensals, a large proportion of the fungi so associated being 

 described as new species. 



[Plant enemies and diseases in Switzerland], H. Muixeb-Thubqatj, A. 

 Ostebwaldeb, and O. Schneideb-Obelli (Landw. Jahrb. Schweiz, 31 (1917), No. 

 5, pp. 416-426). — The department received during the year specimens or ac- 

 counts indicating Injury by a considerable number of animals and microorgan- 

 isms to fruit, garden, and other economic plants. 



[Java plant diseases], W. Roepke (Meded. Proefstat. Midden-Java, No. 28 

 (1917). p. 16). — This report mentions briefly abnormal growths of cacao, coffee, 

 and Hevea, also canker and a root fungus (Hymenochwte noxia) of the last 

 named. 



Life history studies in Sclerotinia, F. J. Seaveb and W. T. Hobne (Mem. 

 Torrey Bot. Club, 17 (1918), pp. 202-206, pi. 1).— The author reports finding in 

 Van Cortlandt Park, New York City, on rootstalks of Geranium maculatum a 

 fungus (conidial form of Botrytis sp.) described as new and named Sclerotinia 

 (Stromatinia) geranii. 



A new Plasmodiophoraceae, Ligniera isoetis, B. Palm (Svensk Bot. Tidskr., 

 12 (1918), No. 2, pp. 228-232, figs. 5).— An account is given of the parasitization 

 of Itoetes lacustris by an organism which is technically described as a new 

 species under the name L. isoetis. 



Plasticity of biologic forms of Puccinia graminis, E. C. Stakman, F. J. 

 Piemeisel, and M. N. Levine (Jour. Agr. Research [U. fif.], 15 (1918), No. 4, pp. 

 2M-250, pis. 3. figs. 9). — In an account of cooperative investigations made by 

 the Minnesota Experiment Station and the U. S. Department of Agriculture, 

 the authors give the results of extensive experiments with a number of forms 

 of rust from different hosts from different regions to determine the theoretical 

 and practical importance of the plasticity of biologic forms of P. graminis. 

 The authors have also investigated the possible r61e of the barberry as a 

 bridging host and its effect as a reinvigorator of the rust. Material was ob- 

 tained from many different sources, most of the work being done with the 

 tritici and secalis forms, although a number of others were included in the 

 investigation. 



The barberry was found not to increase the host range of biologic forms and 

 not to act as a reinvigorator of the rust. Many hosts equally susceptible to 

 the rust were used in an attempt to change the parasitism of the two forms, 

 but without evident results. The authors consider that the data presented In 



