546 EXPERIMENT STATION RECORD. [Vol.38 



A somewhat extensive test was made on apples, plums, cherries, peaches, 

 and grapes of a dust mixture composed of 85 per cent very finely ground 

 sulphur and 15 per cent lead arsenate pow^der, the latter being omitted when 

 not required for insect control. The results have been previously noted 

 (E. S. 11., 37, p. 832). In case of apples treatment with calcium arsenate and 

 soluble sulphur resulted in leaf fall and reduction of the size of the fruit. 



Peach yellows and little peach have been shown to be spread by budding 

 healthy stock with material from diseased trees. A considerable proportion 

 of the pits from diseased trees (8 per cent) have grown, and none have as yet 

 (after three years) developed the disease. 



[Plant diseases in Ontario] (Ann. Rpt. Ontario Agr. Col. and Expt. Farm, 

 42 {1916), pp. 15-18). — While certain fungus diseases were favored by the cold 

 wet weather during the spring, some others which generally cause serious loss 

 were unusually scarce, owing presumably to the dry weather of the summer 

 months. The mo.st injurious' diseases of the year were peach leaf curl {Exoas- 

 cus deformans), apple scab {Venturia pomi), leaf spot or shot-hole fungus of 

 cherry (CyUndrosporium padi) , and raspberry cane blight {Coniothyrium 

 fuckelii). Winterkilling was also reported of raspbei'ry and cherry, the latter 

 having been almost completely defoliated by the shot-hole fungus during the 

 previous summer. 



Diseases thought to be new to Ontario are rust of cultivated snapdragons 

 and a damping-off disease of young tomato plants, both of which are briefly 

 discussed. The former is said to be due to Puccinia antirrUini, the latter to 

 Phytophthora infestans. 



The results of experimentation during four years indicate that late blight 

 of celery may be prevented by spraying with 4 : 4 : 40 Bordeaux mixture when 

 the plants are in the seed bed and at intervals of ten days or two weeks 

 thereafter throughout the growing season. Lime-sulphur is not recommended 

 for celery blight, but the results of one year's test with sulfocide indicate that 

 this substance may prove to be a cheap substitute in this connection for 

 Bordeaux mixture, which is now expensive on account of the high cost of 

 copper sulphate. 



Studies have been carried on in the life histories of the fungi causing leaf 

 spot of currants and gooseberries. Overwintered currant leaves bearing Sep- 

 toria ribis have always developed Mycospliwrella grossularite, the ascospores 

 giving rise to a Septoria infecting Ribes spp. and presumably being S. ribis. 

 Plants have also been infected directly with the ascospores. R. aurea is also 

 infected with a species described as S. aurea, a perfect stage of which has 

 been found and studied, and for this the name M. aurea has been proposed. 



A report is made on investigations regarding the cause and control of a 

 disease of winter tomatoes. This does not seem to be carried in the seed, and 

 no organism has been isolated. Steaming the soil is not effective. 



Only one white pine infected with blister rust was found. 



[Plant diseases in Scotland, 1915], R. P. W^right et al. (Rpt. Bd. Agr. 

 Scot., 4 {1915), pp. LI, LIT). — The total number of new cases of wart disease 

 of potato reported during 1915 is given as 252. Experimentation has added 

 to the list of known resistant varieties 2 early, 4 second early, and 12 late 

 or main crop varieties. It is thought probable that the power of resistance to 

 this disease may diminish from year to year. The formalin treatment for in- 

 fected soil, as tested in a garden in which the disease had been present in 

 severe form, proved entirely ineffective. 



Inspection control measures regarding American gooseberry mildew having 

 been neglected during the year 1914, the disease reappeared during 1915 in 

 more virulent form and over greater area than formerly. It appears that where 



