DISEASES OP PLANTS. 549 



differentiated from tliose of 8. trifoliorum. Tlie fungus, wliich is described, is 

 thought to represent a new species. 



Diseases of ginseng, A. Vuillet (Jour. Agr. Trop., 13 (1913), Nos. U/l, pp. 

 78, 79; lJf2, pp. 110-112). — Among the diseases and enemies discussed, with 

 remedies prescribed, are Altemaria panax, Theilavia basicola, Sclerotinia 

 libertiana, 8. panacis, Phytophthora cactorum, Pythium debaryanum, a Rhizoc- 

 tonia, and Heterodera radlcicola. 



Investigations on potato diseases (fourth, report), G. H. Pethybkidge 

 (Dept. Agr. and Tech. Instr. Ireland Jour., 13 (1913), No. 3, pp. U5~468, 

 pis. 6).— This is a report of investigations on potato diseases in continuation 

 of those previously noted (B. S. R., 27, p. 446), the diseases considered being 

 essentially the same. 



Spraying and other experiments for the control of the late blight of pota- 

 toes, due to Phytophthora infestans, are reported upon at some length. Spray- 

 ing with Bordeaux and Burgundy mixtures gave rather conflicting results, a 

 slight advantage, however, being in favor of the use of Bordeaux mixture. 

 Investigations have shown that the best results were obtained when the 

 plats were sprayed t^ice, beginning about the middle of June. The next best 

 result was obtained by spraying 3 times, in which an earlier spraying was 

 given to the plats. Comparisons were made of different strengths of Bordeaux 

 and Burgundy mixtures, and where 1 per cent copper sulphate was used the 

 results were practically as satisfactory as where a 2 per cent mixture was 

 employed. Treating tubers with Bordeaux mixture before planting was without 

 effect in controlling the disease. Notes are given on the resistance of different 

 varieties, the presence of resting spores of the fungus, etc. 



Further notes on the stallv or Sclerotium disease are given in which it 

 appears that the infection of this disease is due directly to spores and not to 

 vegetative mycelium in the soil. It had been previously noted, through acci- 

 dent, that the occurrence of this disease was correlated with the time of 

 planting, and the investigations reported show that the number of plants 

 attaclvod by the stalk disease diminishes with increased lateness of planting. 



The heating of tubers for 4 hours at 50° C. was found not to affect injuriously 

 the tubers used in planting, but had a reverse effect in reducing the amount 

 of disease due to Bacillus melanogenes. 



In experiments reported on the use of fungicides for disinfecting the soil in 

 connection with the powdery scab, where flowers of sulphur was placed in the 

 soil at the rate of 650 lbs. per acre, there was not only an increased yield of 

 potatoes but a decided decrease in the percentage of diseased tubers harvested. 



An account is given of the pink rot due to P. erythroseptica, a more technical 

 account of which is given on page 550. This disease is believed to be contracted 

 from the soil and appears to be most prevalent on land where potatoes are cul- 

 tivated from season to season. There seems to be little evidence that it is 

 communicated from tuber to tuber during storage, and for its prevention the 

 selection of sound seed tubers and rotation of crops are recommended. Brief 

 notes are given on the curl, leaf roll, and sprain of potatoes. 



Potato tuber diseases, W. A. Obton ( V. 8. Dept. Agr., Farmers'' Bui. Slflf, 

 pp. 16, figs. 16). — Popular descriptions are given of a number of the principal 

 diseases of the potato, with suggestions for their control. 



Potato diseases and methods of control, M. T. Cook (Neto Jersey Stas. 

 Circ. 18, pp. 4)- — Notes are given on a number of the more common diseases of 

 the potato, with suggestions for their control. 



Late blight and rot of potatoes, M. F. Baeeus (New York Cornell Sta. Circ. 

 19, pp. 77-83, figs. 7). — ^A description is given of the late blight or rot of pota- 



