450 EXPERIMENT STATION RECORD. 



rubber. The results are tabulated and discussed. Up to 11 years of age the 

 composition of the rubber is uot materially altered. 



The author is of the opinion that in a climate generally suitable for the cul- 

 ture of Manihot, profitable quantities of rubber may l)e procure<l from trees 

 growing either at high or low altitudes and either remote from or adjacent to 

 the coast. To support this opinion, analyses are given of samples of rubber 

 from 27 trees growing in various parts of German East Africa and in altitudes 

 ranging from 50 to 1,350 meters above sea level. Allowing for difference in 

 the age of trees, no great variation was noted in the amount of rubber produced 

 from trees grown in the different sections. 



DISEASES OF PLANTS. 



Seed treatment for the smuts of winter barley, F. I). Healu {Wehraska 

 Sta. Ri)t. 1907, pp. .'i5-53, figs. -}),— Winter barley has been grown at the ex- 

 periment station for the past 3 years, and has been found to be badly infected 

 with smut, the plat grown in 1905 showing 10 per cent of smut and that in 1906, 

 15 per cent. Since seed treatment for barley smuts has not been as satisfactory 

 as with some other cereals, it was considered advisable to compare some of the 

 different methods and to try a number of modifications. The barley was af- 

 fected by 2 species of smuts, the covered smut {Ustilago hordei) and the naked 

 smut {U. nuda). 



The trejitments consisted of seed treatment with formalin, hot water, corro- 

 sive sublimate, and copper sulphate. The formalin solutions were of strengths 

 varying from 1 pt. to 10 gal. of water to 1 pt. to 25 gal. The hot-water treat- 

 ment consisted of a preliminary soaking of the seed in cold water for 4 hours, 

 after which it was set away in the wet sack for 4 hours more. It was then 

 warmed by submerging in water at 110 to 120° F. for a few minutes, after 

 which it was immersed in hot water, 126 to 130°, for 5 minutes, and then 

 spread to dry. The corrosive sublimate treatment consisted of solutions of 3 

 parts corrosive sublimate in 1,000 parts of water, and half strength of the 

 above. With the copper sulphate treatment, one lot was immersed in copper 

 solution (1 lb. to 24 gal. of water) for 12 hours, then in lime water for 5 

 minutes, after which it was spread to dry. With the other lot, the treatment 

 consisted of soaking the seed in water for 6 hours, then in copper solution (1 

 lb. to 18 gal. of water) for 6 hours, followed by a lime water treatment and 

 drying as usual. 



The results of the different treatments are shown, from which it appeal's that 

 barley smuts can be very greatly lessened by the use of any of the treatments 

 employed. The more effective treatments and those recommended are formalin 

 solution, using 1 pt. to 20 to 25 gal. of water, the hot-water treatment, and the 

 copper sulphate treatment. 



Cotton wilt, W. A. Okton ( V. S. Dept. Agr., Farmers' Bui. 333, pp. 5-2'h figs. 

 11). — A popular account is given of the disease of cotton variously known as 

 wilt, blackheart, trenching, etc., due to Neocosmospora vasinfecta. The field 

 characters of the disease are described, and the various factors which influence 

 its development are discussed. An account is given of experiments in breeding 

 resistant plants, and some varieties of upland cotton that have proved nearly 

 resistant to this disease are described. 



The potato rot, G. Gand,\ra (Estac. Agr. Cent. [Mexico] Boh 2, pp. 20, 

 figs. 19). — A description is given of the potato rot due to Pliytophthora infestans. 

 with suggestions for its control by the use of fungicides. 



Spongospora solani, or corky scab, T. Johnson (Econ. Proc. Roy. Dublin 

 aSoc, 1 (1908), No. 12, XX, pp. 453-^64, pl i).— While investigating the yellow 





