854 EXPERIMENT STATION RECORD. [Vol.38 



The crown canker disease of rose, L. M. Massetx" {Phytopathology, 7 {I'.ill), 

 No. 6, pp. JtOS-417, figs. S). — The author reports having his attention called in 

 September, 1916, to a hitherto unreported disease of roses grown near Phila- 

 delphia. Subsequently, plants affected with the crown canker disease were re- 

 ceived from growers in Missouri, Pennsylvania, Indiana, iMlchigan, Massachu- 

 yetts, and New York. Botli grafted plants and those gi'owing on their own roots 

 are said to be affected, and it is considered questionable whether any variety 

 is inunune. From the investigation thus far carried on, the author believes 

 that this may prove to be one of the most important diseases of roses grown 

 under glass. So far no record of the disea.^e on plants gi-own out-of-doors lias 

 been made. 



Plants are affected at the crown, usually just at the surface of the soil, the 

 lesion in advanced cases frequently extending several inches above the soil. 

 The first indication of the disease is a slight discoloration of the bark, the color 

 rapidly deepening to black and the tissues appearing water-soaked. Soon cracks 

 appear in the bark, extending into the wood. Later a swelling of the stem 

 occurs at and above the affected areas and the cracks become deeper and more 

 evident. One very noticeable characteristic of the disease is said to be the 

 punky consistency of the diseased tissue, especially that underground. Suckers 

 developing from the roots of diseased plants are usually spindling and yellow 

 and are commonly affected at the point of attachment to the main stem. 

 Affected plants do not die quickly but yield increasingly poorer and fewer 

 blossoms. 



The crown canker disease is said to be caused by the fungus Cylindrocladium 

 scoparium, and a detailed account is given of its pathogenicity, cultural charac- 

 ters, and moisture relations. 



Experiments are said to be under way in the hope of developing some 

 method of control for the crown canker of the rose, but at present soil steriliza- 

 tion and the exercise of care in using only healthy stock and scions seem to be 

 the only feasible methods of controlling the disease. 



Cronartiuru cerebrum on Pinus resinosa, J. 11. Weib and E. B. Hubert 

 {Phytopathology. 7 (.1917), No. 6, pp. 450, 451). — The Norway pine (P. resinosa) 

 is usually considered free from attacks of tree rusts, but the authors report 

 infection by C. cerebrum on a young Norway pine tree which stood in a dense 

 staml of 7'. banksiana heavily infected v.nth the rust. 



The sig'nificance of diseases in the economy of Malayan rubber planta- 

 tions, A. SiiAKPLES (Roy. Bot. Gard. Kew, Bui. Misc. Inform., No. 6 (1917), pp. 

 225-229). — A review is given of researches on fungus diseases of Ilevea hrasili- 

 ensis in Malaya. Two instances of serious attack by root diseases are cited as 

 showing the necessity for active measures in sanitation. A practice which has 

 been effective in the past in combating diseases was to grow more ti'ees than are 

 absolutely necessary in order to provide a compensatory growth to offset the 

 ravages of root disease. Conditions for the spread of fungus diseases are said 

 to be more favorable at the present time in Malaya than in any other rubber 

 growing region, so that this practice is now ineffective and the menace from 

 disease is becoming serious. The two main requirements of the present time 

 are a physiological investigation regarding the role of the latex in the metabolic 

 processes of the plant and the extent of the interference of latex exti*action 

 with the development of the tree. 



Bark canker in Hevea brasiliensis, A. Shaeples {Roy. Bot. Gard. Keio, Bui. 

 Misc. Inform., No. 6 {1917), pp. 219-225). — The author has collected observa- 

 tions on Hevea bark canker which have been made in various rubber growing 

 regions. These are considered to show that the present situation is most un 



