1917] DISEASES OF PLANTS. 149 



that humidity is more important than carbon dioxid in the amount of scald in 

 apples in storage. The results obtained from the investigations are said to 

 suggest the importance of a relatively low temperature and an open pack for 

 the prevention of scald. 



Brown blotch of the pear, G. W. Maktin {Abs. in Phytopathology, 6 {1916), 

 No. 1, pp. Ill, 112). — A brown blotch of the pear which is said to cause a serious 

 disfigurement of the fruit is reported as having been present in the orchards of 

 New Jersey for a number of years. This pear disease seems to have been con- 

 fused with russeting, which is characteristic of many varieties of pears, and 

 had not been recognized as a pathological condition. It is said to be due to a 

 fungus which is identical with one described under the name Macrosporium 

 sydoicianum as causing a similar disease in Italy. 



It is claimed that the disease may be readily controlled by two late spray- 

 ings. 



The parasitism of Valsa leucostom.a, R. C. Walton and D. C. Babcock {Abs. 

 in Phytopathology, 6 {1916), No. 1, pp. 112, 113). — Inoculations with this fungus 

 resulted in 100 per cent infection on the trunks and larger branches of peach 

 trees, cankers being formed in about a month's time. No infections were se- 

 cured where mycelium was placed over lenticels without wounds. Inocula- 

 tions of both green and ripe peach fruit gave 94 per cent infection, while plum 

 fruit inoculated gave 97 per cent. Inoculations made in tips of peach branches 

 gave 85 per cent infection, while all checks remained free from disease. 



A preliminary report on investigations of leaf spot of cherries and plums 

 in Wisconsin, G. W. Keitt {Abs. in Phytopathology, 6 {1916), No. 1, p. 112). — 

 While engaged in a study of diseases of cherry and plum at Sturgeon Bay, 

 Wis., the author found that the most serious leaf injury is due to CyUnclrospo- 

 rium spp. 



A study was also made of Coccomyces hiemalis which causes leaf spot of 

 sour cherry. This disease, it is claimed, was quite satisfactorily controlled on 

 sour cherry trees which received their first application of spray when about 

 three-fourths of the petals had fallen. Field observations indicate that early 

 spring infections could be greatly reduced by plowing under or otherwise dis- 

 posing of leaves about the bases of trees. 



The Surinam witch-broom disease of cacao, J. B. Roeek {Bui. Dept. Ayr. 

 Trinidad and Tobago, 15 {1916), No. 1, p. 5). — This is a discussion of the article 

 by Stahel already noted (E. S. R., 34, p. 847). 



Chestnut tree disease in Ardeche, L. Tbabut {Compt. Rend. Acad. Agr. 

 France, 2 {1916), No. 15, pp. 462, 463). — Reporting observations made in 1915 

 on the progress of the chestnut-tree disease in Ardeche, the author recommends 

 the substitution of the cork oak, some varieties of which are resistant to cold, 

 and of Quercus ballota, some varieties of which furnish edible acorns. 



The influence of the tannin content of the host plant on Endothia para- 

 sitica and related species, M. T. Cook and G. W. Wilson {New Jersey Stas. 

 Bui. 291 {1916), pp. 3-47).— A report is given of an investigation carried on 

 cooperatively by the Bureau of Plant Industry of this Department and the 

 New Jersey Experiment Station, in which the effect of tannin on the growth 

 of the chestnut blight fungus {E. parasitica) and related species was studied. 

 Commercial tannin preparations and some special extracts from chestnut 

 bark were used in the experiments on cultures of E. parasitica, E. radicalis, 

 and E. radicalis mississippiensis from different sources. 



The results obtained with commercial tannin were not always comparable 

 among themselves nor with those obtained when the specially prepared ex- 

 tracts were used. In almost every instance, without regard to the form of 



