1919) DISEASES OF PLANTS. 51 



Potato wilt, T. O. B. Osborn (Jour. Dept. Agr. So. iutt, 20 (1917), No. 11, pp. 

 S6.' f , 865). — The author, Inspecting several areas in the Mount Gambler district 

 where diseased potatoes had been reported, found a wilted condition prominent 

 among the symptoms associated with various fungi, among which were Verti- 

 (illium alboatrum and Phovia sp. These fungi are being studied and will be 

 reported upon later. 



Experiments with eelworm-infested potatoes, F. B. Headley (U. S. Dept. 

 Agr., Bur. Plant Indus., Work Trurlcce-Carson Expt. Farm, 1917, pp. 18-21). — 

 Preliminary investigations at the Nevada Experiment Station having Indicated 

 that eelworms and their eggs in potatoes are killed at a temperature between 

 35 and 40° C. (95 to 104° P.), the author was led to test the efficacy and prac- 

 ticability of this method of treating seed. A lot of badly infested potatoes was 

 secured and different portions were heated at 30, 35, and 40' for various periods 

 from 6 to 24 hours. After treatment with heat, the potatoes were soaked in a 

 corrosive sublimate solution for 2 hours before planting. 



It was found that germination was apparently stimulated by treatment at 

 30° and was decidedly decreased by that at 40°, regardless of the length of time 

 they were treated. At the time of harvesting, a careful examination was 

 made of the tubers to determine the amount of eelworm infestation, and it ap- 

 peared that treatment at either 35 or 40° resulted in a marked reduction of 

 the infestation in the crop. The original seed used was very heavily infested, 

 and it is thought probable that with lightly infested seed the percentage of eel- 

 worrns surviving treatment would have been somewhat less. 



[Sugar cane diseases in the Hawaiian Islands], H. P. Agee (Proc. Haicaii. 

 Sugar Planters' Assoc, 87 (1917), pp. 38, 39, 42. 1,3, 68-76, 77, 78).— In a report 

 of wider scope, it is stated that the eye-spot fungus (Cercospora sacchari) 

 caused considerable damage in certain varieties of cane, being epidemic on 

 Oahu. Yellow-stripe disease was epidemic in parts of Hawaii, and infectious 

 top rot occurred on Maui. An undetermined fungus attacked leaf sheaths of 

 different cane varieties when below the normal as regards vigor of growth. 

 Koot-knot nematodes are reported to be on the increase in the islands, and 

 threaten soon to become a serious pest, as they are able to eliminate susceptible 

 varieties completely. I.ahaina disease, supposedly due to toxic concentrations of 

 black alkali in the soil, was much less prevalent on Oahu following the excessive 

 rainfall of the last two winters. Experimentation has indicated the possibility 

 of correcting, in part, the effects of black alkali by the use of gypsum. 



The report is followed by a discussion of these discuses. 



Chlorosis of sugar cane, P. L. Gile and J. O. Cakrero (Porto Rico Sta. Rpt. 

 1917, pp. 10-20). — The results are given of a study of the chlorosis of sugar cane 

 which occurs in restricted areas in various portions of the southern part of 

 Porto Rico. Studies were made of the soils in connection with this coadition 

 of diseased plants, and of various treatments for the prevention of the trouble. 



It was found that lime-induced chlorosis occurs on some but not all calcareous 

 soils, and that it is probably caused by a lack of iron in the plant due to the 

 fact that the carbonate of lime depresses the availability of the iron in the soil. 

 On those calcareous soils where chlorosis occurred the availability of iron 

 appeared less than where chlorosis did not occur, but just what conditions served 

 to lower the availability of the iron was not determined. 



Ash analyses of green and chlorotic leaves showed that there is no more lime 

 in the ash of the chlorotic leaves than in the green ones. Apparently, there- 

 fore, chlorosis can not be attributed to an increased assimilation of lime. 



In attempting to correct the trouble, the authors found that chlorosis can 

 be prevented to some extent by the application of stable manure containing 

 ferrous sulphate and stable manure alone, although large applications did not 



