844 EXPERIMENT STATION RECORD. 



DISEASES OF PLANTS. 



Factors affecting susceptibility to disease in plants, I, G. T. Spinks {Jour- 

 Agr. Sci. [England], 5 (1913), No. 3, pp. 231-2.'{1, pi. J).— This is an account of 

 investigations regarding chiefly the relations existing between nutrition and 

 susceptibility to disease in plants, wheat being the host and Erysiphe graminu 

 the fungtis employed, certain constituents of the standard nutrient solution 

 being varied or replaced in the several cultures in order to test the influence of 

 each on the growth of the plantlets. The conclusions reached are as follows : 



" Susceptibility to mildew and yellow rust in wheat, and to mildew in bar- 

 ley, is increased by providing the plonts with large amounts of available nitro- 

 gen; ammonium sulphate and sodium nitrate seem to be equally effective in 

 this direction. Mineral manures, especially potash salts, on the contrary, de- 

 crease the susceptibility to disease but can not counteract the effect of large 

 quantities of nitrogenous manures. Plants which are semistarved as regards 

 nitrogen exhibit a considerable degree of immunity, even if the phosphates and 

 potash are also present only in small quantities. 



" Lithium salts are also effective in producing immunity, while nitrates of 

 lead and zinc, particularly the latter, render plants extremely susceptible. 

 Other salts of lead and zinc have very little effect on the susceptibility of 

 plants. 



"A variety of wheat which is almost immune to a disease (such as Little 

 Joss to yellow rust) tends 'to retain its immunity even when supplied with 

 excess of nitrogenous food material. 



"Increased immunity does not appear to be due to a lack of food material 

 available for the fungus in the host, . . . because the plants rendered relatively 

 immune by adding phosphates or potash to their food supply were as healthy 

 and well grown as those receiving no such additions. It yet remains to be 

 seen what physiological explanation can be found to account for the changes 

 in susceptibility which can be produced in plants by the above means." 



The sterilization of seed, Ivy Massee (Roy. Bot. Qard. Kew, Bui. Misc. 

 Inform., 1913, No. 5, pp. 183-187, y?s. 2). — Tabulated details are given of nu- 

 merous tests made by the author on various seeds and fungus spores to ascer- 

 tain the effects thereon of hydrogen peroxid bearing on its employment as a 

 fungicide, the general results of which are as follows : 



The spores of fungi, also some kinds of bacteria, are as a rule killed by an 

 hour's immersion in hydrogen peroxid ; no spores experimented with germi- 

 nated after similar treatment for 2 hours. The germination of seeds immersed 

 in hydrogen peroxid was retarded. In some cases the plants from treated 

 seeds are distinctly larger at the end of 3 weeks than those from untreated 

 seeds. For all practical purposes, soaking seed in hydrogen pei'oxid for 3 hours 

 will kill all superficial fungus spores and the seed will not be injured. This 

 method is recommended as a substitute for fumigation, which, as a rule, does 

 not kill fungus spores, unless continued for such a time as to damage the seed. 



Biolog'ical and morphological study of a new Aspergillus, A. Sabtoey and 

 H. Sydow (Ann. Mycol., 11 (1913), No. 2, pp. 156-160, pi. i).— Detailed results 

 are given of the study of A. sartoryi n. sp., which is said to be able to flourish 

 at temperatures up to 48° C. f 



Study of a new Penicillium, A. Sabtoey (Ann. Mycol., 11 (1913), No. 2, pp. 

 161-165, pi. 1). — The author claims this to be a new species closely approxi- 

 mating P. glaucum, but with the difference that this form, P. gratioti u. sp., is a 

 thermophile, bearing temperatures up to 49 or 50° 0. 



A bacteriosis of Ixia maculata and of Gladiolus colvilli, G. Severini (Ann. 

 Bot. [Rome], 11 (1913), No. 3, pp. j^13-424, pi. i).— These studies, carried out 



