1919] DISEASES OF PLANTS. 659 



Control of oak mildew, N. van Poeteren {Tijdschr. Plantengiekten, 24 

 (1918), No. 3, pp. 8S-101). — Having continued observations on oak mildew, 

 which Js reviewed as far bacli as the beginning, in 1908, of the epidemic form, 

 with discussion also of facts noted in 1912 (E. S. R., 28, p. 651), the author 

 states that the injury done, though varying considerably in a given locality, is 

 sufficient to require effective control measures. For this purpose, lime-sulphur 

 is recommended as a suitable spray, one application each season being con- 

 sidered sufficient if applied when the mildew begins vigorous development. 



Pine rust in Sweden, 1917, N, Sylvan (Meddel. Stat. Skogsforsoksanst., No. 

 15 U918), pp. 192-204, XIX-XXII, fig. 1; also in Skogsvdrdsfor. Tidskr., 16 

 (1918), No. 4, pp. S08-S15). — Pine rust {Melampsora pinitorqua) is said to have 

 caused very little damage in Sweden during 1917. The contrast in this respect 

 with the effects during the previous year is thought to have been due mainly to 

 differences in weather. A pi-incipal condition for copious infection of pines and 

 resulting injury is thought to be wet weather during May, or a relatively even 

 distribution of precipitation during this period of spore germination and develop- 

 ment, dry weather during May and early June being unfavorable to the develop- 

 ment of the fungus. 



Pine rust (Melampsora pinitorqua), N. Sylv6n (Meddel. Stat. Skogsforsoks- 

 anst., No. 13-U (1916-17), pt. 2, pp. 1077-1140, CXXVII-CXXXVI, figs. 28; also 

 in Skogsvdrdsfor. Tidskr., 16 (1918), No. 4, pp. 265-307, figs. 28).— This is an 

 account of pine rust in portions of southern Sweden due to M. pinitorqua, 

 regarding Its development and spread as related to weather and to the alternate 

 host (Populus tremula), from which it may spread each year to reinfect the 

 pines. 



[Pine rust in Sweden], N. STi^vfiN (Naturw. Ztschr. Forst u. Landw., 16 

 (1918), No. 3-8, pp. 118-127).— This is an account of the work noted above. 



Summary of the white pine blister rust situation, H. Metoalf (Jour. 

 Forestry, 16 (1918), No. 1, pp. 85-89). — Referring to reports bearing on the ter- 

 ritorial relations of white pine blister rust previously noted (E. S. R., 39, 

 p. 758), the author states that the territorial division of tlie problem then indi- 

 cated still holds, though west of the Mississippi River only four centers of 

 infection have been found, none of them so located as to be dangerous. Cronar- 

 tium on Ribes in Colorado, so strongly resembling C. ribicola as to have been 

 assigned to that species, has been found during the past season to have a 

 Peridermium stage on Pinus edulis and P. monophylla. 



Further notes on black-stripe canker, W. N. C. Belgrave (Agr. Bui. Fed. 

 Malay States, 6 (1917), No. 3, pp. 154, i55).— Discussing further (E. S. R., 39, 

 p. 459) black-stripe canker, the author states that as a general rule black-stripe 

 tissues need not be cut out and that sterilization of tapping knives is unneces- 

 sary if preventive painting is employed. 



Field notes and observations on brown bast, W, N. O. Belgrave and P. W. 

 SotJTH (Agr. Bui. Fed. Malay States, 6 (1918), No. 4, pp. 181-186).— It is stated 

 that, so far as known, rubber trees having once developed the condition known 

 as brown bast never recover under natural conditions, though they continue to 

 live. Practically all methods Intended to be curative or preventive are still in a 

 purely experimental stage. Some of these are discussed with recommendations. 



Experiments on the prevention of brown bast, W. N. O. Belgrave (Agr. 

 Bui. Fed. Malay States, 6 (1918), No. 4, p. 187).— The suggestions here given, 

 being purely experimental, are recommended to be tried out on small areas. 

 Prominence is given to an application of lime raked into the soil over a radius 

 of 5 or 6 ft., washing the trees with lime from the collar to a height of 12 in., 

 and painting with Izal or formalin bisulphite. 



