DISEASES OF PLANTS. 343 



a temporary retarding effect was observed, but this was soon overcome even 

 when tlie treatment was as strong as 5 cc. per 100 gm. of soil. It was found 

 that samples of soil treated with either chemical in sufficient quantity to 

 inhibit entirely nitrification for a period of from 4 to 20 weeks may entirely 

 recover from the effect with reinoculation. So far as the laboratory experi- 

 ments can be applied to field practice, it is thought that neither toluol nor car- 

 l)on bisulphid as previously used could materially affect nitrate accumulation, 

 .since practical applications rarely exceed 0.1 cc. per 100 gm. of soil. 



Preliminary to a study of the i)arasitic flora, the local rusts have been studied 

 and about 400 collections made of TO different species. 



In experimental work with the powdery mildew on oats, it was found that 

 this species will not pass over to wheat, barley, rye, or other grasses tested, 

 although it does infect the tall wild oats (Avena elatior). In studying the 

 effect of light, it was found that etiolated plants will not become infected, 

 even though normal green i>lants of the same varieties are extremely susceptible 

 to the mildew. 



Report of the central station for plant protection in Mecklenburg- 

 Schwerin and ]VIecklenburg--Strelitz, 1912, II. Zimmeemann {Ber. Uaupt- 

 sammclstcUe Pflanzensichutz Mccklcnhurg-Schiccrin u. Strelitz, 1912, pp. 121). — 

 Beginning with an account of the weather during each month of 1912 In con- 

 nection with crops or other vegetation affected thereby, this report then deals 

 in considerable detail with disea.ses of various field and forest plants and with 

 other enemies thereof, giving in some cases comparisons with data obtained in 

 previous years. 



Heat killing and stem constrictions of plants, C. von Tubetjf (Naturw. 

 Ztschr. Forst u. Landxc, 12 {191.'^), No. J, pp. 19-36, figs. 4). — This is a discus- 

 sion of notes by the author and others on growth and behavior of woody 

 plants as influenced by parasitic fungi, compression (from binding), extreme 

 dryness, heat, etc., including studies in regions subject to extremes on several 

 continents. 



The fungus genus Verticillium in its relation to plant diseases, W. A. 

 Orton (Abs. in Phytopathology, 4 (1914)^ ^o. 1, pp. 40, 4i)- — In a previous 

 publication (E. S. R., 30, p. G49) the author called attention to a disease of 

 potatoes caused by V. alboatrum. It is now reported that a similar fungus 

 occurs on eggplants, causing a serious wilt disease. 



Of two wilt diseases of okra, one is said to be due to Fusarium vasinfectum, 

 the other to V. alboatrum. The Verticillium is in general said to be more 

 northern in its range than the Fusarium wilt of okra. 



Diseases of dahlia in Germany and seedling maples in Schleswig-Holstein 

 are associated with Verticillium. 



Studies on Nectriaceae, II, J. TVeese {Ztschr. Gariingsphysiol., 4 (1914), 

 No. 2, pp. 90-132, figs. 2).— The report previously noted (E. S. R., 31, p. 242) is 

 followed by a critical discussion of Nectna peziza, N. suffulta, N. hwmatites, N. 

 cucurbitula meizospora, N. pityrodes, N. erinacea, and N. heterosperma. In con- 

 nection with the treatment thereof notes by numerous other authors are cited. 



Snow mold and other aspects of attack by Fusarium nivale on cereals, 



E. ScHAFFNiT {Landw. Jahrb., 43 {1913), No. 4, pp. 521-648, pis. 5).— This is a 

 more detailed account (E. S. R., 29, pp. 244, 445) of studies by the author with 



F. nivale, including its relations with the host plant in its three stages (on 

 leaves of young plants in early spring, on stems before maturity, and on grains 

 thereafter). Discussion is given also of its cultural and other characters and 

 behavior in connection with those of other related or other grain infecting 

 fungi, also of measures for its control. The last mentioned include selection 



