DISEASES or PLANTS. 547 



varieties of potatoes liave been found tli;i( are wliolly resistant to this disease, 

 altliougli some differences have been observed. Tlie cause of variation is not 

 known. 



A bibliofiraphy Is included. 



Report of the plant pathologist, M. T. Cook {Acw Jersey Stas. Rpt. 1913, 

 pp. 793-817, /j/s-. 7). — The author reports the discovery of the silver scurf 

 {Spondylocladium airovireus) of potatoes in the State. Notes are also given 

 of other investigations, and the most common diseases observed during the year 

 are reported according to host plants. 



The report concludes with an account of potato field tests carried on under 

 the suix>rvision of G. W. Martin to determine whether finely pulverized sulphur 

 and powdered arsenate of lead can be dependtxl upon to protect the potato foli- 

 age from insect injury and fungus disease. Four powdered preparations were 

 used and comparisons made with Bordeaux mixture, Paris green, Pyrox, and 

 two other commercial preparations. It is concluded from the tests made that 

 a mixture of pulverized sulphur and arsenate of lead is practicable and effi- 

 cient in controlling the Colorado beetle. The most striking results obtained 

 showed the economy of Bordeaux mixture and also the .short time i-equired to 

 apply powders. Under the conditions of the experiment the cheapest and most 

 efficient preparation used was a dust mixture composed of three parts of sul- 

 phur and one part of arsenate of lead. 



Storag'e rots of potatoes and other veg'etables, W. P. Fraser (Ann. Rpt. 

 Quebec Soc. Protec. Plants [etc.], 6 (1913-lJt), pp. 50, 51). — Brief descriptions 

 are given of black and blue mold rots, late blight rot, dry rot, and soft rot of 

 potatoes. Control measures include crop rotation, careful harvesting in dry 

 weather, and storage in clean, moderately dry cellars at not above 40° F. 



The biolog'y of the apple canker fungus, S. P. Wiltshire {Abs. in Rpt. 

 Brit. Assoc. Adv. ScL, 1913, p. 714)- — Nectria ditissima is said to be a genuine 

 wound parasite, succeeding only in case of injury deep enough for the fungus 

 to reach the wood before it is shut off by the formation of a layer of phellogen. 

 The fungus traverses the intercellular spaces of the cortex, breaks through the 

 cell walls of phloem and cambium, and traverses the woody elements via 

 the pits in the walls, the medullary i-ays offering no special means of access to 

 the interior. 



The host reacts by the formation of i»hellogen, of abnormal wood cells resem- 

 bling those of the medullary rays, and of wound gum in the wood vessels. The 

 mycelium normally does not spread greatly. Inoculation usually occurs by 

 means of injuries due to frost or aphids. Relatively immune varieties of apple 

 may be infected through injuries under suitable conditions, the determining 

 factors being mostly physiological. 



Observations on the life history of the American gooseberry mildew, E. S. 

 Salmon (Ann. Appl. Biol., 1 {191Jf), No. 2. pp. 177-182). — The author, referring 

 to his previous article (E. S. R., 31, p. 545), gives results of a further examina- 

 tion of material, concluding that some of the perithecia of the American goose- 

 berry mildew (SplKerotheca mors-uvce) which are produced in England either 

 do not reach maturity or do not survive the winter. It is claimed that no case 

 of primary infection by ascospores from overwintered material still present on 

 the shoot has been established. It is thought that ascosiK)res from mature 

 perithecia lodged in bark crevices, bud scales, etc., may possibly be the ones 

 which become the source of the early infection noted. 



The control of American gooseberry mildew, G. C. Gough (Gard. Chron., 3. 

 ser.. 56 (1914), Nos. 1J,5J,, pp. 303, 30 J, ; lJf55, p. 3i9).— Giving the advantages 

 and disadvantages of various methods of dealing with American gooseberry mil- 



