1918] DISEASES OF PLANTS. 47 



mal efficiency ; effect of different methods of drying upon the strength and the 

 hygroscopicity of wood : instruments useful in dry kiln work and metho'ds of 

 testing wood ; temperatures and humidities for drying various kinds of lumber ; 

 and humidity diagram. 

 Appended to the work is a brief discussion of special woods f<M" war uses. 



. DISEASES OF PLANTS. 



Wind-blown rain a factor in disease dissemination, R. C. PatjTvWETtee 

 (U. S. Dept. Agr., Jour. Agr. Research, 10 (1911), No. 12, pp. 639-648, fig. 1).— 

 In a contribution from the South Carolina Experiment Station, the author gives 

 additional data relating to wind-blown rain as a factor in disease dissemi- 

 nation. In a previous publication (E. S. R., 37, p. 49) the results of field 

 experiments were described, and in the present paper laboratory investigations 

 are reported upon which were found to confirm previous conclusions. 



It was found that water is splashed by a falling drop only when it falls 

 upon a film of water, and that it is the water of the film which composes the 

 splash drops. The distance of the splash varies according to the size of the 

 drop, depth of surface films, elevation and inclination of surface of impact, 

 and velocity of the wind. A drop of 0.02 cc. in volume falling 16 ft. upon a 

 relatively thin film of water during a wind of 10 miles an hour, splashed 

 water in abundance a distance of 8 ft., or across two rows of cotton, in moder- 

 ate quantities as far as 12 ft., and in slight amounts to 16 ft. 



In the investigation to determine the dissemination of disease in the pres- 

 ence of dew and heavy fogs without wind, it was found that drops from leaves, 

 which are larger than the average rain drops, falling 12 in. upon a film of 

 water will scatter splash drops over an area of 20 to 32 in. in diameter. This 

 fact is believed to account readily for the local dissemination of a number of 

 diseases. 



Attention is called to the probability that wind-blown rain serves for the 

 dissemination of a number of plant diseases. 



[Plant diseases, 1914 to 1916], T. O. Morrison ([Bien.] Rpt. Dept. Agr. 

 Wash., 2 (1915-16), pp. 91-94)- — Pear blight, which has been destructive in 

 parts of the State of Washington since 1910, is thought to be controllable, if 

 not eradicable. Since 1914 apple mildew has been more threatening than 

 previously, Jonathan being the most seriously affected of the commercial 

 varieties. A test with iron sulphid, atomic sulphur, and milled sulphur prac- 

 tically controlled the disease and left the fruit buds in apparently good condi- 

 tion, though scorching followed the use of iron sulphid in some localities. 

 In tests of dry sulphur, iron sulphid, milled sulphur, and atomic sulphur as 

 used against grape mildew, the results from the last three were almost perfect. 



A degree of success was attained in an attempt to combine effectiveness 

 with cheapness in the control of aphids and ants (which were supposed to be 

 responsible for a large proportion of summer spread of blight), this result 

 being obtained by the use of Blackleaf 40 in combination with lime. 



Biologic forms of Puccinia graminis on cereals and grasses, E. C. Stakman 

 and F. J. Piemeisel (C/. S. Dept. Agr., Jour. Agr. Research, 10 (1917), No. 9, pp. 

 429-496, pis. 7). — In a contribution from the Minnesota Experiment Station, 

 the authors give an account of inoculation experiments in cooperation with 

 the Bureau of Plant Industry with P. graminis collected from about 30 species 

 of grasses in the upper Mississippi Valley, part of the northern Great Plains 

 region, and a small area of the Pacific Northwest. 



As a result of the inoculation experiments, a number of biologic forms 

 were found, which, on the basis of their parasitism, may be divided into two 



