DISEASES OF PLANTS. 45t 



Experimeuts with different fertilizers, especially nitrogenous, on the spotting 

 of citrus leaves and the subsequent leaf fall showed that this spotting was 

 probably due to nutrition disturbances initiated by the use of nitrate fertilizers, 

 but could be counteracted by the addition of a phosphatic fertilizer. 



Experiments on the use of copper sulphate as a treatment for die-back, in 

 which 4 gr. of the copper salt in powdered form was inserted beneath the bark 

 of diseased trees, showed after a lapse of about 21 months no beneficial results 

 in controlling the disease. All untreated trees and 35 out of 46 diseased 

 treated trees showed some symptoms of die-back at the close of the treatment. 

 However, all the trees, both treated and untreated, showed a decided improve- 

 ment in their general appearance and the die-back symptoms on both sets were 

 much fewer than at the beginning of the experiments. 



New fungicides for combating the mildew, V. Vermobel and E. Dantont 

 (Prog. Agr. et Vit. (Ed. VEst-Centre), 32 (1911), No. 22, pp. 679-687).— The 

 authors give formulas, methods of preparation, and properties of several new 

 copper sprays, including a modified soda-Bordeaux mixture (E. S. R., 25, p. 

 354), a copper sulphate-soap mixture, a colloidal copper sulphate-soap spray (see 

 page 459), and their new silver nitrate spray (E. S. R., 24, p. 51). The quali- 

 ties of various soaps which may be used in making copper-soap sprays are also 

 discussed. 



Note on the cellulose content of oak wood, which, had been changed by 

 Thelephora perdix, Helbig (Natiiriv. Ztschr. Forst u. Landw., 9 (1911), No. 5, 

 pp. 246-250). — Tests for cellulose were made with the so-called sound wood, of 

 the grayish yellow wood in the neighborhood of the cavities, and of the white 

 lining of the cavities in the wood. The " sound " wood showed 47.18 per cent of 

 cellulose, the grayish yellow wood 66.37 per cent, and the white wood 68.66 per 

 cent, on the basis of the air-dried substance. 



These results show that only a partial change into cellulose of the tissues sur- 

 rounding the cavities occurred, and that more cellulose is found in the immediate 

 lining tissues of the cavities than elsewhere in the diseased wood. 



Notes on some species of Gymnosporangium in Colorado, E. Bethel (My- 

 cologia, 3 (1911), No. 3, pp. 156^160, pi. 1, fig. i).— -The author figures and de- 

 scribes a new species of Gymnosporangium (G. kernicmum) which produces 

 witches' brooms from 2 in. to 2 ft. in diameter on the Utah cedar (Juniperui 

 utahensis) . 



From field obsevations, the distribution, and the apparent roestelial char- 

 acters of jEcidium gracilens, the author believes that it is probably the aecidial 

 stage of G. speciosum. 



The blister rust of white pine, P. Spaulding (U. 8. Dept. Agr., Bur. Plant 

 Indus. Bill. 206, pp. 88, pis. 2, figs. 5). — ^This bulletin gives an account of the 

 European blister rust (Cronartiiim rihicola) of white and other five-needle pines 

 and includes a historical account of the fungus, its distribution throughout the 

 world, its economic importance, hosts, life cycle, nomenclature, description, field 

 characteristics of the blight on Pimis strohus, the source of diseased stock found 

 in America, the blister rust situation in America, methods of combating it, pos- 

 sible effects of new hosts and climate upon the virulence of fungus plant diseases 

 in general, practical suggestions, present system of handling importations, and 

 legislation against plant diseases. 



The disease is claimed to be an exceedingly dangerous one and has caused 

 immense damage to white pine in all European countries wherever it has ob- 

 tained a good foothold. It has been found in Norway, Sweden, Finland, Russia, 

 Siberia, Japan, Austria-Hungary, Italy, Switzerland, Germany, Denmark, 

 Prance, Belgium, Holland, Scotland, and England, and has been introduced into 

 Kansas, New York, Vermont, New Hampshire, Massachusetts, Connecticut, Penn- 



