DISEASES OF PLANTS. 667 



On the specialization of Erysiph.e graminis, E. March al [Compt. Rend. Acad. 

 Sci. I'ariii, 135 {1902), No. 8, pp. -210-212). — A report is given of studies made of this 

 common grass mildew in which reciprocal inoculations were made with material 

 obtained from a number of different host plants. The results of his experiments, 

 which have been already noted above, show that ErysipJie gvdnmm has become 

 specialized on a number of hosts. Descriptions are briefly given of the specialized 

 forms, to which the author gives names based upon the principal host plants. The 

 form species recognized are trltici, hordei, secalis, avenue, pox, agropyri, and hromi. 



Cotton disease in Egypt, G. Delacroix {Agr. Prat. Pays Chands, 2 {1902), No. 

 8, pp. 135-143; Jour. Agr. Trap., 2 {1902), No. 14, PP- 231-233).— Pi. description is 

 given of a cotton disease in Egypt, the diseased material of which was sent to the 

 author for determination. From the description of the disease furnished the author, 

 and the examination of the infected material, he is led to believe that the disease is 

 identical with that known in the United States as cotton wilt. A study of the parasite 

 offers no differences so far as he can determine from that described as Neocosmospora 

 rashifecta (E. S. R., 11, p. 944). The author states that the resistance of Egyptian 

 cotton to disease ol)served in this country does not seem to have been noted in Egypt. 



Cucumber and melon leaf blotch {Jour. Bd. Agr. \_London'\, 9 {1902), No. 2, pp. 

 196-198, pi. 1) . — The fungus causing this disease was first observed and described as 

 Cercos^pora melonis in 1896, and has spread with marked rapidity. It attacks the 

 foliage, causing small pale green spots on the upper surface of the leaf. Tliese gradu- 

 ally increase in size, passing from gray to a brownish or yellowish color. Frequently 

 the leaf becomes dry and crumbles within 24 hours of the first appearance of infec- 

 tion. Such dead leaves are a source of continued infection and should be destroyed. 

 The disease seems to assume destructive tendencies only upon plants grown under 

 glass where high temperature and excessive moisture are present. Such conditions 

 result in the production of soft growth rendering the attack of the fungus possible. 

 The distribution of the disease through shipping boxes has been demonstrated. For 

 preventive measures the spraying with potassium sulphid is recommended. The 

 diseased leaves should be removed and burned, and after the diseased crop is removed 

 the soil should be thoroughly disinfected. 



The finger-and-toe in turnips {.Tour. Bd. Agr. [London], 9 {1902), No. 3, pp. 145- 

 149, fig. 1). — A description is given of the club root of turni2>s caused by P/o.sniod.i- 

 ophora, brassicx. This disease in addition to attacking turnips affects nearly all plants 

 belonging to the family Crucifene. As means for the prevention of the disease the 

 ai>plication of fresh burned lime to infected land is recommended In order to secure 

 the best results this should be spread on the land 18 months or more belore ihe 

 turnip crop is sown. Other forms of lime are more or less effective but none are as 

 efficient as the common burned limestone, which is slaked just before spreading, fn 

 addition to the treatment with the lime the rotation of crops is recommended, and 

 turnips or similar crops should not occupy the land oftener than once in 8 years. 

 Experiments have shown that acid fertilizers encourage the development of this dis- 

 ease and should in no case be used. The author states that while no varieties seem 

 entirely immune to disease some appear markedly resistant. 



Notes on apple rusts, H. H. Whetzel {Proc Indiana Acad. Sci. 1901, pp 

 255-261).— Notes are given on the general prevalence of apple rust throughout the 

 region, and attention called to the fact that while the fungus was exceeding! v abun- 

 dant on cedars during 1900 it was markedly scarce the following season. The 

 Rcestelia stage was sufficiently abundant for the purposes of investigation during the 

 summer of 1901, although not as abundant as the previous year. An experiment 

 was attempted in which parts of apple trees were inclosed with cheesecloth just as tht- 

 buds were beginning to swell and when the teleutospores had not yet ripened .m the 

 cedars. The protected leaves were examined from time to time, and while inlected 



