1916] DISEASES OP PLANTS. 651 



Conceming^ certain peculiar tissue strands in a Protomyces gall on Am- 

 brosia trifida, A. Stewart {Abs. in Scic. -e, n. set:, ^3 (1916), No. 1106, pp. 

 365, 366). — The stems of the great ragweed are said to be sometimes infected 

 by P. andinus, causing the formation of large galls. These usually occur just 

 above the ground, but often higher on the stem, sometimes as much as 2 ft. 

 above the galls which are located near the roots. Both kinds of galls have 

 essentially the same histological structure, the deeper portions near the pith 

 having peculiar tissue strands which are similar in some respects to the tumor 

 strands found in certain plants affected with the crown-gall organism. The fact 

 that the abnormalities in the tissues of the host plants are found in or near to 

 the pith indicates that the stems become infected when quite young. This is 

 offered as a possible explanation as to how the upper galls of the stems are 

 produced. 



Acid sprays as related to scorching, L. Degbully {Prog. Agr. et Vit. {Ed. 

 VEst-Centre), 37 {1916), No. 16, pp. 365-367).— It is stated that while low con- 

 centrations, for example 1 per cent copper sulphate and 0.4 per cent carbonate 

 of soda in Burgundy mixture, are rarely dangerous, the same proportions main- 

 tained in higher concentrations may prove very injurious to foliage. With 

 2 per cent sulphate and 0.9 per cent carbonate, the foliage seldom, if ever, 

 scorches, with 2 per cent sulphate and 0.875 carbonate rarely, while with 2 

 per cent sulphate and 0.75 carbonate the preparation is very strongly acid, and 

 is not ordinarily to be recommended for use after the blooming period. Bor- 

 deaux mixture containing 1 per cent copper sulphate and 0.5 per cent lime 

 (sometimes contaminated by the presence of magnesia) practically always gives 

 an alkaline solution. 



Tlie powdery mildews of Avena and Triticum, G. M. Reed {Missouri Sta. 

 Research Bui. 23 {1916), pp. 3-19).— In previous publications (E. S. R., 21, 

 p. 641), the author showed that the morphological species, Erysiphe graminis, 

 consists of a large number of different races. In a subsequent paper (E. S. R., 

 27, p. 545), the results of infection experiments with the powdery mildew of 

 wheat were given. The present paper gives the results of a large number of 

 additional experiments with E. graminis on Avena and Triticum. Seed of these 

 genera was obtained from various sources, 165 varieties of wheat being tested 

 with reference to their susceptibility to the fungus. A great majority of these 

 varieties proved quite susceptible. All of the eight recognized types or species 

 of Triticum contained susceptible varieties, and only a few distinctively resist- 

 ant varieties were found. 



An account Ls also given of the physiological race of E. graminis which oc- 

 curs on species of Avena. Tests have been made of 41 varieties belonging to 

 17 species, and a great majority have proved susceptible to the oat mildew. It 

 was also found that the wheat mildew readily passed over to certain species 

 of .Slgilops and the oat mildew to Arrhenatherum avenaceum. 



A Phy-tophthora on oats, J. McMuephy {Science, n. ser., 43 {1916), No. 1111, 

 p. 534). — The author reports observing on leaves of oats in California a species 

 of Phytophthora which is said to be similar to P. colocasice. A more extended 

 study, however, is considered necessary to determine the specific rank of the 

 fungus. The markings produced on the oats by the fungus may appear as 

 spots or stripes along one or both margins of the leaf, or as a stripe down the 

 center. The diseased areas become yellowish and then whitish when conidia 

 are abundant. Later these areas, which sometimes have a water-soaked appear- 

 ance, may become brown or reddish-brown, and the parts shrivel and dry up. 



Seed treatment tests, 1914, L. Hiltner {Prakt. Bl. Pflanzenbau u. Schutz, 

 n. ser., IS {1915), No. 6-7, pp. 65-90). — This deals in considerable detail with 

 experiments carried out in Bavaria during 1914 by steeping seed graia of 



