DISEASES OF PLANTS. 749 



Black canker of the chestnut, G. Briosi and R. Fabneti {Ahs. in Hot. Ccntbl., 

 no {1909). yo. 19, 1)1). -',89, ',90).— Accoidiug to the authors, the black canker 

 or root disease of the chestnut is contagious, progressing downward on the 

 trunk from the original source of infection into the roots until the entire root 

 system is invaded. At the base or on the lower parts of the trunks of young 

 trees, a casfcerous outgrowth is found, caused by a fungus parasite for which 

 the name Coryiicum pcniiciosum n. sp. is suggested. 



For young timber vigorous pruning and burning of all diseased wood is rec- 

 (snuuended. following this bj' ))ainting the wounds with mastic, tar, or other 

 disinfectant. On old trees all infected bark and wood should be cut out and 

 the wounds washed with a concentrated solution of sulphate of iron to which 

 sulphuric acid has been added. 



The recent disease of the oak, A. Trotter (Bui. t^oc. Bot. Ital., 1908, No. 

 7-9, pp. 113-117; (tlis. in Hot. Ccntbl., 110 (1909), No. 2',, p. 629).— The oak 

 mildew prevalent in northern and central Italy in 1!)08 attacked Qucrcus 

 peclttnculata, Q. scssiliflora, Q. ccrris, and Q. ilex, causing the death of a large 

 number of young plants. According to the author, the disease was probably 

 due to Microspharu qiicrcina rather than to .1/. alni. 



The Oidium of the oak, P. A. S.vccakdo (Guz. Contadino [Trcuiso]. 1908, 

 No. 32; uhx. in Ccntbl. Bahl. [etc.], 2. Abt., 2.) (1909), No. 19-25, p. 531).— It is 

 stated that in 3907-llM)!) this mildew was widely i)revalent throughout Italy on 

 oak trees. It does not seem to be either Phyllactinia HUffulta, or Oidium qucr- 

 cinum, but more closely resembles the Oidium form of the American mildew 

 (Microspliwra qucrcina). The origin of this new disease is unknown, and so 

 far no general remedy for it has been discovered. 



The dissemination of a new fungus in Italy, " the white disease " of the 

 oak, C. FusciiiNi iRivista [Conegliano], .'/. scr., IJf {1908), No. 18, pp. ^2^- 

 J,26; abs. in Ccntbl. Bakt. [etc.], 2. Abt.. 25 {1909), No. 19-25, p. 530).— The 

 author gives the various localities in Italy where this Oidium disease of the 

 oak has appeared. It is stated that it was so prevalent in some regions that 

 not a single young oak tree could be found that was not attacked by the fungus. 



Witches' brooms and branch knots on stone pine (Pinus cembra), K. voN 

 TuBEUF {Naturw. Ztschr. Forst u. Landic, 8 {1910). No. 1, pp. 1-12, figs. 15). — 

 The author claims that the witches" brooms, galls, and knots on the leaves 

 and branches of conifers may originate from a variety of causes, such as mites, 

 insect larvje, fungi, and bacteria. It is stated that the witches' brooms arising 

 from the buds on P. cembra and probably those on P. montana are caused by 

 a mite {Eriophycs ccm&rcc) and not by the mite {Phytoptus pini) which pro- 

 duces the branch knots on P. silvcstris and P. montana. The branch knots on 

 P. cembra are said to be due to bacteria. 



A new lilac disease, H. Klebahn {Krankheiten des Flicdcrs. Berlin, 1909, 

 pp. 75, figs. .',5; abs. in Bot. Gaz., J,9 {1910), No. 2, pp. 152, 153).— In addition 

 to giving an account of the more common fungi occurring on lilacs used for 

 winter forcing in P]urope, the author describes a new disease which is charac- 

 terized by the attack on the twigs of the plants, the fungus killing them for a 

 distance of several internodes. Usually only the upper internodes are killed, 

 but often the lower parts of the stems are destroyed. The flower buds on the 

 infected twigs do not develop, so that only leafy shoots are produced from the 

 lower uninjured buds. 



It appears that the greater part of the infection occurs while the plants are 

 in storage. A study of the cause led to the conclusion that it is due to Phy- 

 tnphthora syringa\ a species closely allied to P. omnivora, but differing in some 

 of its morphological and biological characters.* 



