1917] DISEASES OF PLANTS. 547 



analogy with O. farinosum. The mycelium appears to winter in the host, adding 

 another example of this adaptive device to those previously noted by others, 

 more recently by Melhus (E. S. R., 34, p. 154). 



An Oidium mildew on carnations, W. B. Mercee (Jour. Roy. Hart. Soc, 41 

 (1015), No. 2, pp. 227-229, fig. 1}.—A fungus noted in 1914 as causing a mildew 

 on carnations and said to be a member of the Erysiphacese has not yet been 

 fully identified. 



A spray which is said to control the disease is made up for keeping in stock 

 by mixing 1.75 lbs. of crystallized copper sulphate and 1 qt. of strong ammonia 

 with 2.5 gal. of water. Before using, each pint of this is to be diluted with 8 

 gal. of water. 



Lime-sulphur, though effective as a fungicide, injures the appearance of the 

 plants. 



The biology of Uredinese on Geranium, Gina Jacob (Centbl. Bakt. [etc.], 2. 

 Abt, U {1915), No. 17-23, pp. G17-658, figs. 7).— Details of a study are given 

 relating chiefly to the biology of the species of Puccinia and Uromyces on 

 Geranium and Polygonum. 



A new leaf spot of Viola cucuUata, H. W. Anderson (Proc. Ind. Acad. Sci., 

 1914, PP- 187-190). — A preliminary report is made on a leaf spot of V. cucullata 

 believed to be caused by a Colletotrichum, not previously noted in this connec- 

 tion, but probably identical with that occurring on V. rotundifolia. 



The control of damping-ofE of coniferous seedlings, C. Hartley and R. G. 

 Pierce (V. S. Dept. Agr. Bui. J53 (1917), pp. 32, pis. 2, fig. i).— Accounts are 

 given of experiments for the control of damping-off of coniferous seedlings duo 

 to various fungi, among them Pythium debaryanutn, Fusarium moniliforme, 

 and Corticiwm vaguui solani. 



Experiments for the control of loss due to damping-off are reported from o 

 number of Forest Service nurseries and elsewhere, in which various methods 

 of soil disinfection were tested. Of the many methods tested, treatments with 

 sulphuric acid, copper sulphate, zinc chlorid, and formaldehyde have proved 

 most satisfactory, but the different disinfectants behaved quite differently at 

 different nurseries. On tlie whole, dilute sulphuric acid has given the best 

 results. Heat disinfection has been only partially effective. In some soils 

 formaldehyde was found to kill dormant seed, while the other chemicals men- 

 tioned caused in some nurseries the death of the root tips of the germinating 

 seedlings. Sulphuric acid as a disinfectant has in some cases resulted in a 

 marked increase in the late season growth of pine seedlings. 



Parch blight on Douglas fir in the Pacific Northwest, T. T. Munger (Plant 

 World, 19 (1916), No. 2, pp. 46, -^7). — A description is given of an injury to the 

 foliage of Douglas fir trees at points in Oregon and Washington. This appears 

 serious in spring in case of isolated trees of all ages on the eastern edges of 

 groves and is ascribed to exposure of these trees to the drying Chinook winds 

 at the time of the year when they are least able to withstand the parching 

 influence of these winds. The injury is most severe on the so-called coast 

 form of the Douglas fir. No permanent effects of this scorching are noted 

 other than perhaps certain deficiencies of development on the most exposed 

 sides of the trees. This form of injury is said to be analogous to the winter 

 injury of white pine in Maine, as described by Morse (E. S. R., 21, p. 144). 

 Parch blight is suggested as an expressive and distinguishing name for this 

 injury. 



The alternate hosts of the white pine blister rust, L. R. Grose (Amer. For- 

 estry, 22 (1916), No. 272, pp. 469-471, figs. iS).— Brief descriptions are given 

 of the wild or cultivated currant and gooseberry, alternate hosts of the white 

 pine blister rust. Species named as of particular importance in this connection 



