DISEASES OF PLANTS. 345 



undraiued portions of the same plat a total loss was experienced. Preliminary- 

 investigations have been begun on the development of a resistant strain of 

 plants. A survey made of the pea industry indicates that a lack of rotation is 

 one of the chief contrihiitory factors in the i)roduction of j)ea blight. 



Lightning injury to potato and cotton plants, Ij. K. Jones and W. W. Gil- 

 liERT {Plnjtopathology, 5 {1915), Xo. 2, pp. D4-102, pis. 2 ; ahn. in Phijtopathology, 

 // (liH.'i), 'So. C), p. J/OG). — The results of an inquiry into the iujury caused by 

 lightning are given, the authors stating that such injury is not uncommon to 

 certain crops, particularly cotton, potatoes, Ijeets, tobacco, and ginseng. 



Belation between Puccinia graminis and plants highly resistant to its 

 attack, E. C. Stakman (U. S. Dcpt. Agr., Jour. Agr. Re.search, Jf (1915), No. 3, 

 pp. 193-200, pi. 1). — In amplification of an account previously noted (E. S. R., 

 33, p. 245), the author gives some results of histological studies of the hyphal 

 invasion of several ])lants by P. graminis. 



It is stated that when plants practically immune to P. graminis are inoculated 

 the fungus gain.s entrance in a jierfectly normal manner. After entrance it 

 rapidly kills a limited number of the plant cells in its immediate vicinity and 

 seems then unable to develop further. 



The relations between plant and parasite in partially resistant and in almost 

 totally immune plants are different in degree only, hypersensitiveuess appearing 

 to be a phenomenon fairly common among both somewhat resistant and almost 

 totally resistJint itlauts. 



A bibliography is given. 



A preliminary report on the relation of grass rusts to the cereal rust 

 problem, E. C. Stakman (Ahs. in Plujtopathology, Jf (1914), No. 6, p. Jtll). — 

 In continuation of previous studies on rust specialization (E. S. R., 31, p. 146) 

 the author reports experiments in which uredospores developed on grasses in 

 the field were used to inoculate wheat, oats, barley, and rye. It Wiis found 

 that Puccinia graminis from Agropyron repens, A. tencrum, A. caniniim, A. 

 smithii, and Ilordeum jubatum transferred quite readily to barley and rye, 

 only occasionally to wheat, and practically not at all to oats. The rust transfers 

 readily from Dactylis ylomerata and Poa ncmoralis to oats, but not to other 

 cereals. 



Attempts were made to transfer rusts occurring on Agrostis alha, A. stolonifer, 

 Antho.vanthum odorutum, Calamagrostis canadensis, Poa pratensis, and P. com- 

 pressa to wheat, oats, barley, and rye, but, with the exception of a few small 

 spores and a very few pustules, the results were entirely negative. 



The ascigerous stage of Helminthosporium teres, A. G. Johnson (Ais. in 

 Phytopathology, Jf {191 Jf), No. 6, p. JfOS). — In the course of studies on the 

 Helminthosporium diseases of barley the author found an ascigerous stage 

 which is considered to be a species of Pleospora. 



Some facts of the life history of ITstilago zeae, F. J. Piemeisel (Abs. in 

 Phytopathology, Jf {191 Jf), No. 6, pp. Jfll, Jfl2). — The author reports inoculation 

 work with sporidia of V. zew which indicates that infection may take place 

 readily without any injury of the tissues, and that the infection is purely local. 

 On very young corn plants successful infection often takes place, but not much of 

 the host tissue is involved. No effect of freezing temperature on the vitality of 

 spores was observed. Spores placed in a silo in the fall failed to germinate 

 within two months from the time they were placed in the silage, but whether 

 they germinated in the silo or whether the various organic acids which are 

 developed during fermentation of the silage destroyed their powers of ger- 

 mination has not been definitely determined. It is considered, however, that 

 the acids probably are the chief agency iu destroying the powers of germination. 



