DISEASES OF PLANTS. 747 



trees, is described. Spraj'ing with Bordeaux mixture, pruning, good cultivation, 

 and proper nourishment, are insisted upon. It is stated that in EgyiJt wheat 

 is attaclced chiefly by Ustiliujo tritici and barley by V. hordci and U. nuda. 



Plant diseases in South Africa, I. B. P. Evans (Agr. Jour. Union So. 

 Africa, 6 (1913), No. 3, pp. 4/(9-455, figs. 5).— Besides brief notes regarding the 

 new phytopathological laboratory at Pretoria, general mention is made of 

 investigations in progress there. Reference is made to some diseases peculiar 

 to the country, such as a bacterial disease of mango prevalent In the Ti-ansvaal 

 and Natal, also to some fungi parasitic on native plants. 



Plant diseases in Java, L. P. de Bussy (Meded. Dcli-Procfstat. Medan, 8 

 (1913), No. 2, pp. 64S8, 82).— Reference herein is made chiefly to studies 

 already reported by Honing (E. S. R., 27, p. 136) and those noted below. 



Bacterial forms obtained from tobacco and other plants showing gammo- 

 sis, J. A. Honing (Meded. Deli-Proefstat. Medan, 7 (1912), No. 6, pp. 223-253, 

 fig. i).— As contributory to the study of the general question whether bacterial 

 gummosis may be ascribed to activity of forms other than Bacilhis sohniacca- 

 rum, the author reports on the physiological and morphological study of a 

 number of bacteria obtained from tobacco, etc. Of these, eleven are described 

 as new species under the following names: Bacterium schiiffnen, B. zinnioidcs, 

 B. sumatranum, B. aurantium-roseum, B. stalactiti genes, B. delicnse, B. patelli- 

 fomie, B. rangiferinum, B. langkatense, B. medanense, and Corynehacterium 

 pinformc. 



Vegetable pathology, E. Jarvis (Ann. Rpt. Dept. Agr. and Stock [Queens- 

 land], 1912-13, pp. 9S-100). — Along with brief notes on diseases already more 

 or less familiar in Queensland, mention is made of a banana disease of unde- 

 termined cause said to be more severe on wet lands; some physiological ab- 

 normalities of potato; a new outbreak of Phytophthora infestans on tubers 

 after immunity for a year; and a disease of cucurbitaceous plants ascribed to 

 ;i Phoma of undetermined species. 



Influence of light on infection of certain hosts by powdery mildews, 

 G. M. Reed (Abs. in Science, n. ser., 39 (1914), No. 999, pp. 294, 295).— The 

 author reports results of investigations to determine the influence of light 

 upon infection of hosts by powdery mildew. Seedlings of barley and wheat 

 that had been grown in darkness until the first leaf was from 2 to 3 cm. long 

 were inoculated with the mildew from their respective hosts. Some of the 

 inoculated plants were kept continuously in the dark, others were removed 

 at once and placed in the light, while still others were retained in the dark for 

 intervals of 24 hours before being placed in the light. In general the period 

 of incubation was retarded proportionally to the time the plant was kept in 

 the dark. In other series of experiments the plants were first grown in the 

 light and then after inoculation placed in the dark, some immediately, others 

 at intervals of 24 hours. 



In the case of plants placed at once in the dark no infection occurred, while 

 those kept in the light for a day or two became infected. The i^eriod of the 

 incubation of the fungus, however, was materially retarded. The author states 

 that in general the effect of the absence of light on the mildew may be con- 

 sidered as an indirect one. Infection fails to occur in those cells which have 

 not developed chlorophyll. This indicates that the mildew is a strict parasite 

 attacking cells which are not capable of carrying on their normal functions. 



These results are quite different from those obtained by inoculating etiolated 

 plants with saprophytic fungi, as under such conditions the saprophytes are 

 able to develop on the living tissues. 



Investigation on foot disease of cereals, A. Guerbapain and A. Demolon 

 (Betterave, 23 (1913), Nos. 597, pp. 3S6-38S, fig. 1; 598, pp. 402-405; 24 (1914), 



