956 EXPERIMENT STATION RECORD. 



receptacle containing the gas at some little distance from the potatoes. Where 

 they were innnertiately over the A-essel in which the formaldehyde and potas- 

 sium permanganate were placed consideral)le injury was done to the tubers. 



From a study made on the effect of the application of lime on the produc- 

 tion of scabby potatoes, it was found that the application of 1,000 lbs. of lime 

 per acre inmiediately before planting tended to increase the percentage of 

 scabby potatoes. Where lime is to be applied to the soil it should be done at 

 least 3 years before potatoes are used in the rotation. 



Notes are given on internal brown spot of potato tubers, in which a peculiar 

 spotting of the interior of the tubers is noticed, although the surface presents a 

 healthy, normal appearance. The variety reported upon was Burpee Extra 

 Early and the tubers were grown on rather dry, sandy loam. So far no organ- 

 Ism has been found connected with this disease, and the trouble is not believed 

 to be transmitted but to be due to some disturbance in the physiological proc- 

 esses of the plant. 



A surface spotting of tubers by Phytoplithora infestans was reported early 

 in 1907, in which black spots varying in size were noticed on the surface of 

 potatoes. It was found that these potatoes had been dug rather early in Sep- 

 tember, when the tubers were not mature and were easily bruised in digging and 

 handling. The si)ores which had fallen on the bruised tubers germinated, but 

 on account of adverse temperature and moisture conditions the mycelium 

 passed into a resting stage instead of penetrating further into the tissues and 

 producing the usual characteristic dry rot of the tuber. 



Notes are given on a disease of potatoes, to which the name blackleg is given. 

 This disease is common in parts of Europe, but has only recently been recog- 

 nized in this country (E. S. R., 19, p. 248). 



In concluding the bulletin the author gives an account of experiments with 

 red lead as an insecticide. It has been claimed that this substance possesses 

 marked insecticidal qualities, but tests made with it showed that while it was 

 a repellant against the larvje of the potato beetle, there was nothing to recom- 

 mend it as a substitute for Paris green as an insecticide. 



The brusone disease of rice, R. Farneti {Atti Cong. Risicolo Internaz., 3 

 (1906), PI). 70-101). — A detailed report is made of investigations on the disease 

 of rice known as brusone or blast, in which the author describes the character- 

 istics of the disease, methods of transmission, influence of temperature and 

 climate on its development, and the various methods which have been sug- 

 gested for its prevention. The author believes that Pincularia ffrisca, P. oryza\ 

 and Hclniintliosixiriuiii turciciiiii, all of which have been described as causing 

 this disease, are different stages in the life history of a single species of fungus. 



The root disease of sugar cane, H. R. Fulton (Louisiana 8tas. Bill. 100, 

 pp. 21, pis. 7). — A description is given of a root disease of sugar cane caused 

 by the fungus Marasmius plicatus a previous account of which has been noted 

 (E. S. R., 19, p. 751). Affected plants have a deficient root development, and 

 the lower sheaths are cemented together about the canes. The fungus grows 

 saprophytically on decaying vegetation and seems to show a strict selective 

 preference for cane plants. Spores are abundantly formed, but as the fruit 

 caps are produced only under favorable conditions, there is probably little in- 

 crease of the fungus through the production of spores. It is believed to spread 

 largely through the mycelium, and causes at times considerable loss. It affects 

 the plants by destroying the roots and smothering the germinating buds by 

 mechanically matting the leaf sheaths over them. 



As preventive measures the author recommends careful cultivation, selection 

 and disinfection of seed cane, the planting of resistant varieties, destruction of 

 infected trash, and resting the cane lands. 



