DISEASES OF PLANTS. 643 



a survey which was made with a view to securing a home supply of mine 

 proi)s and other mining timher to talie the place of that imiwrted previous 

 to the present war. 



The hardness of ■woods, G. Janka {Mitt. Forstl. Vcrsuchsw. Osterr., No. 

 39 (1915), pp. VII-{-117, pU. 4)- — I" continuation of previous investigations 

 (E. S. II., 20, p. 754) the author conducted hardness tests of some 2SG kinds 

 of coniferous and deciduous woods. Determinations were also made of the 

 .specific gravity, comi)ressive strength, and shriulcage of the woods. The results 

 are here presented in detail and discussed at length. The investigation was 

 conducted primarily with a view to formulating a numerical classification of 

 the hardness property of different kinds of native and foreign woods occurring 

 in the Vienna trade. 



Investigations on the accuracy of volume computations of stems by using 

 the average diameter and length, M. Kunze (Mitt. K. Sachs. Forstl. Ver- 

 suchsaiist. TJiannidt, 1 (1912), No. 1, pp. 5.J). — The author here presents a study 

 of volume and length measurements for various kinds and classes of trees in 

 Germany. 



The general conclusion is reached that the form factor of unbarked stems 

 decreases regularly with an increasing average diameter and increases regu- 

 larly with an increasing stem length. This relation was most marked with 

 pine trees. The influence of diameter and length on the form factor is some- 

 what less when the bark is removed, but the variation of the form factor due 

 to the absence of bark in the individual species Is so small as to be negligible. 



DISEASES OF PLANTS. 



Report of the botanist and plant pathologist, H. W. Barre (South Carolina 

 Sta. Rpt. 1914, PP- 20-25). — ^The author reports additional investigations on the 

 anthra<'nose of cotton, studies of which have been in progress for a number of 

 years. In undertaking to control this disease the hot-water treatment has been 

 investigated, and there was found to be a difference of about 20° C. between the 

 thermal death point of the fungus in culture and the temperature at which the 

 seed is killed. Following up this information it was found that cotton seed 

 would stand a treatment of 75° C. in water for 10 minutes without injury. 

 Plants that have been grown to maturity from treated seed have shown no 

 presence of disease. In cooperation with the North Carolina and some other 

 experiment stations variety tests of cotton for resistance to anthracnose are 

 being carried on, but the author states that while thei'e is consideral)le variation 

 in the amount of disease on different varieties there has thus far been found 

 no indication of very marketl resistance. 



Notes are given of studies that have been begun on bacterial diseases of cotton 

 and on some physiological disturbances of tlie cotton plant. 



Under the author's direction a plant disease survey of the State is being 

 made, and one of the important discoveries of the past season was the occur- 

 rence of Phiisodcnna zcir-mniHlis on corn. Some cooperative work is briefly 

 reported on the wilt of cotton and cowpeas. which is carried on with this De- 

 partment and with planters throughout the State. 



Notes of some plant diseases of 1913, W. P. Fraser (Ami. Rpt. Quebec Soc. 

 Protec. Plants [etc.], 6 (1913-14), pp. 45-50, figs. 3).— The following diseases 

 were noted on the farm of Macdonald College in 1913 : 



Downy mildew of alfalfa (Pcronospora trifoliorum) was held in check, prob- 

 ably by the very dry summer of 1913. No effective control measures have been 

 found. Koot and stem rot (Selcrotinia trifoliorum) was not as i)revalent as in 

 1912 on fleld alfalfa, but clover grown uu exiierimeutul plats suffered severely. 



