DISEASES OP PLANTS. 49 



Resistance to chlorosis, A. YERNExnL and R. Lafond (Rev. Vit., 36 {1911), 

 No. 927, pp. 321-326). — During 1911 chlorosis appeared vei-y destructive in 

 certain regions of France to varieties of grapes hitherto considered resistant 

 even when planted in lime soils. The season was a very rainy one and fol- 

 lowed an unusually wet year. Previously, chlorotic vines treated with iron 

 sulphate had given good crops, but in 1911 all failed. 



A study was made of the vines, and especially of the maximum quantity of 

 lime in the soils where the more resistant varieties could grow without showing 

 chlorosis. The resistance to lime was found to vary with the different varieties, 

 and the depth and character of the subsoil were found to influence materially 

 the growth of the vines. Some varieties of grapes were found to tolerate as 

 much as 45 per cent of lime in the soil, while the ordinary Riparia stock will 

 not withstand much more than 10 per cent. In deep rich soils that are not 

 excessively moist the tolerance was even higher. The authors claim that in 

 the establishment of vineyards which are to remain for many years the depth 

 and character of the subsoil must be taken into consideration. 



Infection of grapes by downy mildew, J. J. Krankoff (Prog. Agr. et Tit. 

 {Ed. VEst-Ccntre), 33 {1912), NO: 11, pp. 33.'i, 335).— A brief account is given 

 of spraying experiments for the control of mildew, which in 1911 was success- 

 fully combated by early and repeated sprayings. The application was made 

 almost exclusively to the upper side of the leaves, thus confirming the conclu- 

 sions of Ravaz and Verge (E. S. R., 26, p. 550). 



The conditions necessary for the appearance of downy mildew, L. Ravaz 

 and G. Verge (Prug. Agr. et Vit. {Ed. VEsi-t'enire), 33 {19J2), No. 10, pp. 296- 

 300). — A study has been made of the relation of temperature to the appearance 

 of the conidia of the downy mildew, Plasmopara viticola (E. S. R., 26, p. 851). 

 Infested leaves were kept in thermostats and the temperature and time required 

 for the appearance of the characteristic white spots of the mildew were noted. 



None appeared at temperatures below 13° C. but they did show after 20 

 hours at that temperature. At about 20° the development is most rapid, a 

 single day or night with this temperature accompanied by suitable humidity 

 being all that is needed to induce a rapid growth. The development is some- 

 what slower at higher temperatures. In the spring of the year the temperature 

 and other conditions at Montpellier are said to be seldom suitable before May 

 27 to promote the rapid spread of the fungus, while in autumn the conditions 

 are usually very favorable and frequent successive invasions of the fungus are 

 to be expected. 



Experiments in the treatment of grapevine mildew in the Bombay Presi- 

 dency, W. Burns {Dcpt. Agr. Bombay Bui. Jf5, 1911, pp. 15, pis. 4)- — An ac 

 count is given of spraying experiments in which Bordeaux mixture was used 

 for the control of the downy and powdery mildews of grapes. Two years' work 

 has shown that thorough and timely spraying gi'eatly reduces the loss com- 

 monly due to these fungi. The author notes the apparent resistance of one 

 variety to mildew and frost injury. 



The relation of meteorological conditions to diseases of the mulberry, G. 

 Arnaud and F. Lafont {Ann. Eeole Nat. Agr. Montpellier, n. sen, 11 {1912). No. 

 3, pp. 169-215, figs. 25). — A report is given on the relation of weather conditions 

 to attacks of Neetria cinnaharina and Coryneuni mori on the mulberry, the 

 studies on the former having been carried on at Montpellier, while the report 

 on the latter is largely based on the work of Butler (E. S. R., 22, p. 51). So 

 far as the Neetria is concerned, and probably the same is true for the Coryneum, 

 the authors believe that their occurrence as parasites on the mulberry is asso- 

 ciated with the injury of the developing buds by late spring frosts. The 



