242 EXPERIMENT STATION RECORD. 



recognized as a serious disease. It does not appear to be limited to any par- 

 ticular soil type, topography, or season. The disease first makes itself evident 

 by the tree putting out undersized, more or less crinkled and yellow mottled 

 leaves. The axes of growth are usually shortened so that the leaves are 

 clustered together into a sort of rosette. In well-marked cases the branches 

 usuMlly die b;ick from the tip and other shoots are developed from normal or 

 adventitious buds and in turn those pass through the same series of symptoms. 



The nonparasitism of the disease seems to be rather definitely established 

 by results obtained in isolation cultures, inoculation tests, etc. As a result 

 of experiments in pruning, fertilizing, transplanting, etc., it is considered 

 that the disease is directly or indirectly caused by some soil relation. 



The evidence at hand appears to indicate that pecan rosette belongs among 

 the chlorotic diseases of plants which are noninheritable and noninfectious, 

 but due mostly to improper nutrition or injurious physical conditions. 



A beech disease {Roy. Bot. Gard. Kew. Bui. Misc. Inform., A^o. 4 (191.'f), p. 

 176). — Reference is made to a contribution by Elsie M. Prior (E. S. R., 30, p. 

 653). The action of wind on the crown of the tree in connection with the 

 tapering form of the trunk may, it is thought, cause cracking of the stem at a 

 somewhat definite height as noted, giving access to Polijporus adust us, the 

 fungus found in alleged causal connection with the diseased condition. 



Hevea canker, I, II, A. A. L. Rutgers {Dept. Landh., Nijv. en Handel 

 [Dutch East Indies], Meded. Afdeel. Plantensiekten, Nos. 2 {1912), pp. 10, pis. 

 6; 4 {1913), pp. i-7).— Continuing previous work (E. S. R., 29, p. 248), it is 

 stated that Hevea canker has appeared in Java, Sumatra, and Borneo. Its 

 presence and progress are marked by a cessation of latex flow, claret-colored 

 patches under the cork layers of the bark, and later an enlarging discoloration 

 of the inner layers. This is followed by the formation of woody tissue (or 

 wound cambium) around the dead brown cells in the inner cortex, which 

 formation may continue even long after the infection itself is past. 



Measures for eradication of the disease are those securing increa.sed access 

 of air and sunlight, as thinning, pruning, and removal of intercrops; prevent- 

 ing spread in the tissues by removal of all diseased portions of the cortex 

 without disturbing the cambium (which requires specially trained workmen) ; 

 disinfection of tapping knives by means of formalin ; and preventing infection, 

 as by spraying the stems with Bordeaux mixture. 



In the second paper, the proper employment of carbolineum on first appear- 

 ance of the canker is outlined and recommended. Cultural and climatic con- 

 ditions and tapping as bearing upon progress and control of the disease are 

 also discussed. 



Bordeaux mixture. — I, Physico-chemical studies, O. Butler {Phytopathol- 

 ogii, .'i (191Ji), No. 3, pp. 125-180, pis. 2, figs. 3). — Preliminary to an investigation 

 of the biological properties of Bordeaux mixture, the author gives an account of 

 studies of the physico-chemical nature of this important fungicide, in which he 

 describes the chemistry, effect of weathering, physical properties, and methods 

 of preparation and properties of various types of Bordeaux mixture. 



Summarizing his conclusions, he states that Bordeaux mixture may be com- 

 posed of one or several basic cupric sulphates or mixtures of basic cupric sul- 

 phates, depending on the ratio of cupric sulphate to calcium oxid employed. The 

 copper precipitate of Bordeaux mixtures in which the ratio of cupric sulphate to 

 calcium oxid is 1 : 1 or 1 : 0.5 becomes crystalline on standing when the solution 

 contains more than 0.125 per cent of cupric sulphate. The rate of crystalliza- 

 tion depends on the temperatui'e and concentration of the cupric sulphate in the 

 mixtures. The crystallization was found to be retarded by the presence of such 



