652 EXPERIMENT STATION BECOKD. 



on barley has ordinarily the widest, while the leaf rusts on barley and i-ye have 

 the most restricted, range; (5) under favorable conditions all the stem rusts 

 can be carried successfully to the four cereals; (6) when rusts are transferred 

 to imcongeuial hosts, if pustules are produced they are small and weak; (7) 

 two biologic forms may inhabit the same cereals without being identical; (8) 

 by gradual variation and adaptation to varying conditions a rust Species widely 

 distributed may form a number of strains or tyi)os, differing in physiological 

 reactions; (9) the host plants exercise a strong influence not only on the 

 physiological and biological relatioushii)S, but in some cases even on the mor- 

 phology of the uredospore." 



Many investigators hold that the secidial stage serves to reinvigorate the 

 fungus, and to test this theory continuous cultural experiments with the 

 uredosi)ores of different grain rusts were undertaken by the authors, and 52 

 successive uredo generations of each rust grown without the intervention of 

 any other spore form and without any diminution in the vigor of the rust tested. 

 It is claimed that the uredo stage of P. graininis and P. rubifjo-vera live over 

 the winter in the United States, as evidenced by work of previous investigators 

 and confirmed by experiments cited in this bulletin. It is claimed that rusts 

 in the uredo or i3ecidial stages are present in different parts of the country at 

 all times of the year, and by means of the wind or other agencies these spores 

 may be carried from regions where they are abundant to places where the grain 

 is in a receptive condition. It is claimed that the uniformly low temperature 

 during the critical months of 1904 was a very important factor, if not the de- 

 termining factor, for the rust epidemic of that year. The bi'eeding of rust- 

 resistant A^arieties of grain is the only method promising a successful com- 

 bating of grain rusts so far as discovered. 



A bibliography of 106 titles is appended. 



Fusarium on cereals and its effect on germination and the wintering 'of 

 the grain, L. Hiltneb and G. Ihssen {Landw. Jahrb. Bayern, 1 {1911), Nos. 1, 

 pp. 20-60, figs. 8; 4, pp. 315-362, figs. 2; ahs. m Deut. Landw. Presse, 3S {1911), 

 No. 6, pp. 55-58, figs. 3). — The authors claim that the poor stands of winter 

 grains often seen are due to attacks of Fusarium nivale which originate from 

 seed-borne spores of the fungus. 



Special attention is called to the results obtained from experiments on seed 

 disinfection with a 1 per cent solution of corrosive sublimate, in which better 

 germination, more vigorous growth, and greater yields were obtained than with 

 the untreated grain on the check plats. 



A cytological investigation of the grain rusts and the mycoplasm theory 

 of Eriksson, F. Zach {Sitzber. K. Akad. Wtss. [Vienna], Math. Naturw. Kl., 

 119 {1910), I, No. 4, pp. 301-330; abs. in Bot. CentbJ., 116 {1911), No. 1, pp. 17, 

 18; Centbl. Bakt. [etc.], 2. Aht., 30 {1911), No. 4-6, pp. 98-100).— A cytological 

 Study is reported of the leaves and stems of Secale affected by the" uredospore 

 mycelia of Piiccinia graminis and P. glumarum, in which the so-called plas- 

 monuclei of Eriksson and also other smaller bodies were observed. The larger 

 nucleus-like bodies the author concludes are not real nuclei, but are probably 

 haustoria in the cells. 



Wheat rust {Dept. Agr. Egypt, Agr. Notes, 1911, No. 1, pp. 6). — In a discus- 

 sion of rusts in general and of wheat rust in particular, the claim is made that 

 only one species of w^heat rust is known in Egypt, probably Puccinia graminis. 



On the curly leaf disease of cotton, G. Kranzlin {Pflanzer, 6 {1910), 

 Nos. 9-10, pp. 129-145; 11-12, pp. 161-110).— K study is reported of the develop- 

 ment of this disease, the alteration in the host produced by it, the condition of 

 the various organs of the plant, and the influence of climate and soil on the 

 disease. 



