»19] DISEASES OF PLANTS. 849 



B19-828, pis, 3). — In n contribution from the Virginia Bxperlmenl Station, the 



authors describe a leaf spol disease of tobacco canted by Bacterium anouiatun 



n. sp. The disease is said to have been prevalent in the Hue cured tobacco 

 belt of Virginia in 1917, apparently having been present to some extent foe 

 several years, and it may have a wide distribution. The disease produces 

 losses in both yield and grade, which were calculated in one held at 20 pet 



cent reduction in yield and 40 per <-ont reduction In grade. 



Ergot on Manitoba wheat, J. ('minor {Gompt. fiend. Aoad. \<ir. I 

 4 U'M8), No. S3, pp. 931-934). — The presence of ergol (Olavicept pur p u re a i on 

 .Manitoba wheat imported into France is briefly discussed in connection with 

 the degree of resistance offered by that variety to the disease. 



The eelworm disease of wheat and its control, I,. P. Btabs (/'. B. /'< pt. 4<ir., 

 Farmers' Bui. 1041 (1919). pp. 10, figs. 10). — A popular account is given of the 

 nematode or eelworm disease (Tyhnchus tritici) of wheat, B previous report 

 upon which has already been noted (B. S. R., 39, p. 649 i. 



To avoid infection, the author recommends the use of clean y<-f<\. crop rota- 

 tion, and sanitation. In order to secure clean seed, the employment of the salt 

 brine method is advised. This consists in placing the wheat in a 20 per cent 

 salt solution, stirring thoroughly, and skimming the nematode galls and other 

 light material from the surface of the liquid, the sound grains sinking to the 

 bottom. After treatment with the salt solution, the grain should be rinsed in 

 fresh water and dried. 



Drought injury to Mcintosh apple. H. T. Gussow (Phytopathology, 8 <191S). 

 No. 9, pp. 490, 491, fig. 1). — Injury to apples of the Mcintosh variety o b s erve d 

 In 1917 and 1918 is described, this being attributed to the extraordinarily sev< 

 drought of 1917 and the lack of precipitation at certain periods In 19is. 



Apple scald, C. Brooks, J. S. Cooley, and D. F. Fisher {.lour. Agr. R* >ar<h 

 [V. S.], 16 (1919), No. 8, pp. 195-217, figs. 11).— In continuation of studies on 

 the effect of various factors on apple rot fungi and the scald of apples in 

 storage (E. S. R., 36, p. 649; 38, p. 353), the authors give a report of additional 

 work conduct ml in the Bureau of Plant Industry, U. S. Department of Agri- 

 culture, on the nature and control of apple scald. 



Apple scald is claimed to be due to volatile or gaseous substances that are 

 produced in the metabolism of the apple and can be taken up by various ab- 

 sorbents. Well matured apples are less subject to scald than immature o: 

 and apples from heavily irrigated trees scald worse than those from trees re- 

 ceiving moderate irrigation. In storage the development of apple scald was 

 found to increase with a rise in temperature up to 15 or 20° C, but the 

 trouble has not been observed to occur at 25 or W°. The effects of water 

 vapor, carbon dioxid, and oxygen on the development of scald were [nvestlgal 

 and it was found that scald was considerably reduced by decreasing the 

 humidity, although the beneficial effects were not entirely due to the decreased 

 moisture in the air. Accumulations of carbon dioxid did not favor the devel- 

 opment of apple scald, rather tending to prevent it. and apples susceptible to 

 scald were made immune by storing them for a tew days in an atmosp 

 pure carbon dioxid. The effect Of Ventilation on scald in storage is reported 

 upon, it having been found that thorough aeration aids materially in redtsdng 

 the amount of injury due to this cause. 



Spraying- tests at Te Kauwhata. J. F. ShzpHKBD (Jour. Agr. [New Zrn!.]. lit 

 (1918), No. 4, pp. 228-230).— Tests were made with various fun-bides used 

 dormant sprays against black spot of pears, the results being somewhat in- 

 conclusive. Spraying with lime-sulphur controlled apple mildew with no 

 detriment to the foliage. 



