290 PATHOLOGY [BoT. Absts., Vol. VII, 



2023. GiDDiNGS, N. J., AND Anthony Berg. A comparison of the late blights of tomato 

 and potato. Phytopath. 9:209-210. 1 pi. 1919.— A preliminary report upon the patho- 

 genicity of three strains of Phytophthora infestans isolated from potatoes (2 strains) and 

 tomatoes (1 strain). The strain from tomato showed greater pathogenicity for young tomato 

 plants than did either of the two strains from potato. Sporulation of the potato strains 

 occurred very sparingly on the spots produced on the tomato leaves. — G. H. Coons. 



2024. MacMillan, H. G. Wind, and the distribution of pathogenic soil organisms. Phy- 

 topath. 9:471-474. 2 fig. 1919.— A hypothetical discussion of the relation of dust storms 

 to the distribution of soil organisms.—/. G. Dickson. 



2025. Pantanelli, E. Contributi alia biologia della peronospora della vite. [The biology 

 of the peronospora of the vine.] Rev. Patol. Veg. 10: 51-72. 1920.— In studying the condi- 

 tions favorable for the infection of the grape by Plasmopara viticola, it was found that soil 

 moisture and humidity of the air both have an influence on the stomatal openings. If the 

 soil moisture is below 15 per cent the stomata do not open unless the humidity of the air is 

 above 80 per cent. If the soil moisture is above 20 per cent, the stomata open, provided the 

 humidity of the air does not go below 40 per cent. The condensation of water on the foliage 

 has an action opposed to that of the soil. The higher humidity of the air also favors attacks 

 by the fungus because of its effect on the composition of the leaves, the latter having under 

 these conditions a higher proportion of soluble carbohydrates, nitrogen, and phosphorus. 

 That the stomates are closed in young leaves is held to be a sufficient reason why infection 

 does not commonly take place; these young organs also contain little sugar and starch, and 

 nitrogenous compounds soluble in water are almost completely absent. No close parallelism 

 was found between the concentration of the cell sap and receptivity, though increase of turges- 

 cence seemed to be favorable to the fungus. A study was made of the chemotactic influence 

 of various substances on the zoospores. Analyses of spots in the leaf showed that in the 

 oily spots the starch had decreased but that there had been an increase in a zone surrounding 

 the spots over that in the rest of the leaf. The percentage of sugar had decreased in the 

 spots also, but the surrounding zone and the rest of the leaf had the same sugar content. 

 Studies were made of the nutrition of the fungus, in the leaf. Bibliography appended.— 

 F. M. Blodgett. 



2026. Reddick, Donald, and V. B. Stewart. Transmission of virus of bean mosaic in 

 seed and observations on the thermal death-point of seed and virus. Phytopath. 9: 445-450. 

 1919.— Hypodermic injections of juice from mosaic bean plants failed to produce disease 

 in beans although high percentage of infection was obtained by rubbing juvenile leaves with 

 crushed diseased leaves. The disease is not readily communicated from plant to plant by 

 ordinary contact. Seeds from diseased plants immersed for 4 hours in bleaching powder 

 solution gave 50 per cent of mosaic plants. Dry heat treatments ranging from 60 (1 to 24 

 hrs.) to 80°C. (10 min.) failed to kill the virus, although the higher temperature injured the 

 viability of the seeds. Moist heat (70°C. for 15 min.), although reducing germination mark- 

 edly, did not kill the virus. — G. H. Coons. 



2027. Snell, Walter H. Observations on the relation of insects to the dissemination of 

 Cronartium ribicola. Phytopath. 9:451-464. 1919.— The author gives a list of species of 

 insects bearing aeciospores in varying quantities found in June, 1919, on or near blister rust 

 lesions on Pinus Strobus, and a list of insects bearing urediniospores found in 1918 on Ribes 

 bushes. The author concludes that while the spread of Cronartium ribicola by insects from 

 pine to Ribes or vice versa may be infrequent and accidental, the spread of the uredinial 

 stage upon Ribes probably occurs with some regularity.— J. G. Dickson. 



2028. Taylor, Minnie W. The overwintering of Cronartium ribicola on Ribes. Phyto- 

 path. 9:575. 1919. 



