1917] diseasp:s of plants. 651 



Beproduction in the coniferous forests of northern New England, B. 

 Moore {Bot. Gas., 64 (1917), No. 2, pp. 149-158).— A paper on this subject de- 

 livered at the meeting of the Ecological Society of America in New York City 

 in December, 1916, in which the author gives the results of an investigation 

 undertaken to determine the factors governing the reproduction of the more 

 important coniferous trees in the forests of northern New England. A bibli- 

 ography of literature cited is included. 



Growth study of planted trees, H. Dork, jr., and W. A. Boag {Forestry Ann. 

 [Mich. Ayr. Col.], 2 (1917), pp. 37, 38).— A table is given showing the growth 

 performance of various hardwood species planted in 1909 in the forest nursery 

 of the Michigan Agricultural College. 



Frustum form factor volume tables for sugar maple, E. G. Hamlin {For- 

 estry Ami. [Mich. Agr. Col.]. 2 {1917), pp. 14-18, fig. i).— The tables here pre- 

 sented were prepared with a view to determining the feasibility and accuracy 

 of the frustum form factor method in preparing volume tables. The data were 

 secured in Wexford County, Mich., during 1915 and 1916. 



A study of breakage, defect, and waste in Douglas fir, E. .7. Hanzlik, 

 F. S. Fuller, and E. C. Ekickson {hniv. Wash. Forest Club. Ann., 5 {1917), pp. 

 32-40, fig. 1). — A short study was made in the spring of 1916 to secure data 

 upon breakage, defect, and waste in logging Douglas fir timber. The results are 

 here presented in tabular form and are supplemented by a report on breakage 

 in Douglas fir timber as observed in thi-ee typical logging camps during 1915. 



On the influence of the age of the trees on the quality of the rubber, O. 

 DE Vries {Arch. RubhercuU. Nederland. Indie, 1 {1917), No. 3, pp. 169-177).— 

 A number of special experiments were conducted to determine the influence of 

 the age of rubber trees on the quality of the rubber. 



The results in general show that the tensile strength of rubber from older 

 trees is not appreciably better than from young trees. The slope or type of 

 the stress strain curve is generally the same, although sometimes somewhat 

 better for old trees. The rate of cure diminishes in an appreciable degree with 

 the age of the tree and the viscosity for old trees is nearly always better. 



The preservative treatment of poles, B. L. Grondal {Univ. Wash. Forest 

 Club Ann., 5 {1917), pp. 8-11, fig. 1). — In this paper the author discus.ses mod- 

 ern methods of treating poles, including the recently developed perforation 

 process in which the poles are pierced in a number of places to insure greater 

 penetration of creosote just above and just below the ground line where fungi 

 ai*e most active. 



Mapping methods, C. M. Cade {Forestry Ann. [Mich. Agr. Col.], 2 {1917), 

 pp. 19-24, fig. 1). — A discussion of present practice in mapping land areas, in- 

 cluding forest tracts. 



DISEASES OF PLANTS. 



Report of the associate plant pathologist, C. D. Shekbakoff (Florida Sta. 

 Rpt. 1916, pp. 80-98, figs. 5). — The line of investigations reported upon is 

 .similar to that previously noted (E. S. R., 35, p. 844), including studies of 

 diseases of vegetables and a disease of pineapples. 



Chief attention has been paid to damping-off of seedlings, Rhizoctonia sp. 

 being the most troublesome fungus in Florida in this respect. Experiments in 

 the control of damping-off have been carried on, and the application of 0.5 per 

 cent copper sulphate solution has given good results with lettuce, the seeds 

 germinating normally and no damping-off following. For seed disinfection, 

 formalin and corrosive sublimate have been compared, the author having found 

 in the use of corrosive sublimate with a number of kinds of seeds, particularly 



