DISEASES OP PLANTS. 851 



The chlorosis of grapes during the spring G. Peovost-Dumarchais (Jour. 

 Agr. Prat., n. ser., 22 (1911), No. 33, pp. 210, 2ii).— Attention is called to the 

 disappearance of chlorosis in some of the vineyards of France in the spring of 

 1911 following a period of hot, dry weather. The author believes that this teuds 

 to substantiate his theory that downy mildew and chlorosis are in some way 

 correlated, and that as there was no mildew the chlorotic conditions was out- 

 grown. He thinks it a mistake to consider that chlorosis is due solely to a 

 superabundance of lime in the soil. 



How is the grape infected by mildew? H. MiJLLER-THURGAtr (Prog. Agr. et 

 Vit. (Ed. VEst-Centre), 32 {1911), Nos. 39, pp. 367-371; Jf2, pp. //5^-^59 ) .—The 

 results are given of an investigation on the infection of grapes by the downy 

 mildew (Plasmopara viticola). The conclusions, which are essentially the same 

 as given elsewhere (E. S. R., 26, p. 450), indicate that in general infection 

 takes place through the under surfaces of the leaves. 



The influence of temperature on the germination of the conidia of downy- 

 mildew, L. Ravaz and G. Verge {Prog. Agr. et. Vit. {Ed. VEst-Centrc), 33 

 {1912), No. 6, pp. 170-177, figs. 3).— A study was made of the effect of tempera- 

 ture on the germination of the conidia and zoospores of Plasmopara viticola. 



The development of the zoospores and the conidia was found to take place 

 rapidly at all the temperatures which are favorable to the growth of grapes, 

 especially during rain or mist. Temperatures above 29° C, such as prevail on 

 fine days, were found unfavorable to their development. The germination of 

 the zoospores always took place at the low temperature, as in case of the 

 conidia, and was quite constant. 



Roncet, E. Pantanelli {Reprint from Vit. Moderna, 17 [1911], No. 10-11, 

 pp. 35; Ztschr. Pflansenlcranlc, 22 {1912), No. 1, pp. 1-38, figs. 29).— -This dis- 

 cussion summarizes available data as to this disease, and gives the results of 

 the author's anatomical and physiological investigations therewith. 



The fungus diseases of cacao, C. J. J. van Hall {Agron. Trop., 3 {1911), 

 No. 3, I, pp. 33--'f3). — Attention is called to the fact that there are many errors 

 in the literature relating to cacao diseases, and to rectify some of them the 

 author, in a paper presented before the International Congress of Tropical 

 Agriculture at Brussels in 1910, briefly describes some of the more important 

 diseases, their causes, and methods for their control. The diseases enumerated 

 are those caused by Phytophthora sp., Fusarium colorans, Diplodina cacaoi- 

 cola, Corticittm javanicum, CoUetotrichiim hixificxmi, Stilbella nana, Hymcno- 

 chcete noxia, and Taphrina hussci. 



Diseases of orchids caused by bacteria, G. L. Pavaeino {Atti R. Accad. 

 Lincei, Rend. Ch, Sci. Fis., Mat. e Nat., 5. ser., 20 {1911), II, No. 5, pp. 233- 

 237). — Technical descriptions are given of some new species of bacteria causing 

 diseases of cultivated orchids. Among those described are Bacterium cattleyce 

 on Cattleya si^p., BaciUus poUacii on Odontoglossuni citrosmum. Bacterium 

 krameriani on Oncidium kramerianurn, and BaeiUus farnetianus on Oneidium 

 ornithorincum, and C. crispa. 



A disease of tulips, A. Lendner {Bui. Soc. Bot. Oendve, 2. ser., 3 {1911), 

 No. 3, pp. 126-131, figs. Ji; Bui. R. Soc. Toscana Ort., 3. ser., 16 {1911), No. 12, 

 pp. 3.'fJf-3.'t9, figs. 4). — A disease of tulips is described in which the bulbs are 

 attacked by Botrytis parasitica. The author believes that a Sclerotium causes 

 part of the trouble, and he states that the differences in size of the sclerotia as 

 well as their structure indicate that B. parasitica and what he calls Sclerotium 

 tiiliparum are not identical. 



Previous notes on this disease have been given (E. S. R., 15. p. 48S; 16, p. 

 1095). 



