1019] 



DISEASES <)F PLANTS. 745 



in 14 representative fences, with an average age of 11 years, an average of 

 65 per cent <>f tiic posts were still sound aa compared with an average of 65.2 

 per < ■• - 1 1 1 soinni oak posts of aboul the same age. In fences where neatness Is 

 more desired than durability tamarack is straight and holds the staples welL 

 Where durability Is the principal requirement, posts of locust, catalpa, or cedars 

 are recommended. 



The structure and use of the Parana pine forests of Brazil, II. V Whitfobd 

 (Jour. Forestry, il (1919), No. .'., pp. /■',', 158).— A brief descriptive account of 

 these forests ami their present use ns a source of forest products. 



Philippine bamboos, \V. II. BBOWM and A. P. PiBCHEB ([Philippine] Bur. 

 Forestry Bui. 15 (1918), pp. •■'.'. i>in. S3). — The various species are described, and 

 growth data are given on bamboo plantations established by the Philippine 

 Bureau of Forestry. 



Philippine forest products as sources of paper pulp, W. II. Bbown ami A. F. 

 Fischkk ([Philippine] Bur. Forestry Bui. 16 (l'.USt, pp. IS. pi. 1). — This bulletin 

 calls attention to a haiuhoo (Bchizostachyum lumampao) ami two gras 

 (Imperata exaltata) ami talahlb (Saccharum spontaneum) , which offer imme- 

 diate prospects tor paper pulp. Information is given relative to experiments 

 conducted to determine the value of these materials, together with suggestions 

 on utilization of a number of other trees ami plants for paper making. 



DISEASES OF PLANTS. 



The biochemistry of resistance to disease in plants (Minnesota Sta. Rpt. 

 1918, pp. J{0, l^l). — In the study of the biochemistry of disease resistance in 

 plants, the physiological effect of hydrocyanic acid upon plants, the funda- 

 mental nutrition of Sclerotinia spp., the enzyms of S. cinerea, and the bio- 

 chemistry of resistance to cereal rusts have been investigated. 



In the investigation of the nutrition of Sclerotinia, a thorough study Is being 

 made of the source of carbon and nitrogen, the mineral requirements, etc., 

 of the fungus, and considerable progress is reported to have been made on the 

 study of the source of carbon and the reaction of the medium. Oxalic and 

 citric acids have been proved to be frequent products of the growth of the 

 fungus, the character of the medium determining the amount of the acids 

 present. 



In the study of the enzyms of S. cinerea, pectase has so far been found to 

 be the most common one. 



In the investigation of the biochemistry of resistance to cereal rusts, at- 

 tempts to grow PuCCinia graminis in the absence of living host cells have given 

 negative results. The hydrogen-ion concentration ami the specific electrical 

 conductivity of the juices from both resistant and susceptible wheats under 

 different conditions were determined. The hydrogen ion concentration was 

 found remarkably uniform, and the results to date are considered to show that 

 it is extremely doubtful whether the hydrogen-ion concentration per se is 

 involved in the phenomena of resistance. The specific electrical conductivity 

 of the juice paralleled rather closely the ash content. 



Some experiments were conducted on the germination and growth of spores 

 of Fusarium lini In the sterile juices of resistant and nonresistant flax plants. 

 The fungus spores were found to germinate less readily and to grow less 

 vigorously in the juices of resistant plants. 



[Report of] division of plant pathology (Washington Sta. Bui. 7.".} (1919), 

 pp. 85-87). — A progress report is given on some of the investigations carried on 

 during the year ended June 30, 1918. 



