DISEASES OF PLANTS. 49 



application of Tenax; one or more Septoria of undetermined species on the 

 same plant; O'idiuin ericinum causing the mildew of Erica gracilis, also a rust 

 on the same, said to be new and named Uredo ericw n. sp. ; a twig blight of 

 Camellia, attributed to a Myxosporium of undetermined species; and certain 

 frost injuries with recovery of apples, which are thought to bear important 

 relations to precipitation, temperature, etc., before and after the freeze proper. 

 Injury to veg'etation by oxalic compounds and the absorption of foul 

 gases by grapes, F. Muth {Jahresher. Ver. Angew. Bot., 9 {1911), pp. 218-2.',0, 

 pi. 1, figs. 5). — In a case where trees, garden plants, and vineyards showed 

 damage referred to emanations from adjoining chemical works, analyses of the 

 powder deposited on the foliage showed that oxalic acid or its salts made up 

 nearly one-third thereof, also that sodium compounds were present. Pot and 

 field experiments demonstrated that the characteristic injuries may be produced 

 by powdering the leaves, especially the lower sides, and the flowers, with talc 

 containing even a small percentage of oxalic compounds, and in less degree and 

 strictness by similar treatment with sodium hydroxid or carbonate. The 

 hydrogen ion, in case of oxalic acid, seemed to be the primary injurious agent 

 and the negative ion of secondary importance, as the injury was less for the 

 acid salt than for the acid and still less for the neutral salt. The oxalic com- 

 pounds dissolved in the soil water api^eared to be without injurious effect, sup- 

 posedly on account of the lime present in the soil. The abnormal taste of the 

 wine from the grapes grown in the neighborhood was attributed to their absorp- 

 tion of the foul gases permeating the air of the vicinity. 



A twig disease of fruit trees due to bacteria, A. Ostebw alder (ScMoeiz. 

 Ztschr. Obst u. Weinbau, 1912, pp. 197-200; ahs. in Ztschr. Landw. Versuchsw. 

 Osterr., 15 {1912), No. 12, p. 1303).— The author states that a drying of floral 

 leaves and twigs on fruit trees, which recently appeared in Wudenswil, is due to 

 Bacillus amylovorus. 



Notes on three limb diseases of apple, G. W. Wilson {North Carolina Sta. 

 Rpt. 1912, pp. 47-55, figs. 6).— Descriptive notes are given on the New York 

 canker due to Sphceropsis malorum, European canker caused by Nectria ditis- 

 sima, and a disease of apple twigs the cause of which has previously been re- 

 ferred to the genus Thelephora, but which is now reported as being due to 

 Septobasidium pediciUatum. The different fungi causing these diseases are 

 described, their distribution indicated, and preventive treatment suggested. The 

 treatment consists of cutting out the diseased portions and spraying with some 

 good fungicide. 



Infection of apple leaves by cedar rust, H. R. Fulton {North Carolina Sta. 

 Rpt. 1912, pp. 62-66). — ^A report is given of experiments on a considerable num- 

 ber of varieties of apples to determine the possibility of inoculating leaves with 

 cedar rust spores sprayed upon them at different times in the spring. Inocula- 

 tions were made almost daily from March 26 to May 7, and decided differences 

 in susceptibility of varieties were noted. Two periods of artificial infection 

 were observed, about April 1 and April 21, the spots indic-ating the presence of 

 the fungus being noticed about 10 days after the inoculation dates mentioned. 



The experiments carried on during the season of 1912 showed that the teleuto- 

 spores of the fungus were capable of germination for about six weeks, but that 

 they formed infection spores abundantly only when there was continuous wet 

 weather for about two days. The infection of apple leaves was produced by 

 these spores only when the wet weather was more prolonged, giving a chance 

 for germination after distribution of the spores. Only a portion of the leaves 

 on any twig were found to have been infected at any one time, and the suscep- 

 tibility of the leaves was determined by their age. 



