PROCEEDINGS, 1917 



83 



While these figures do not show all that should be shown in a rainfall chart, they 

 do show that the years of greatest rainfall do not correspond to the years of greatest 

 spray injury. 



The question of relative humidity has been looked into and so far as we have re- 

 cords we would not be justified in saying that it had any definite relations to spray 

 injury. 



RELATIVE HUMIDITY FOR THREE YEARS. 



May 

 June 

 July 



These figures show that during May and June 1917, the air contained about the 

 same amount of moisture as during the two preceding years. During July 1917 the air 

 carried slightly more moisture than during the two preceding years. 



In conclusion, it may be said that lime sulphur injury may be influenced by a num- 

 ber of factors, which appear as follows, in order of importance for Nova Scotia. 



First, the direction in which the spray is applied. It is the lime sulphur that is ap- 

 plied to the under side of the leaf that causes the damage. 



Second, the period at which lime sulphur is used. The least injury is caused by 

 the early sprays, the damage increasing with each successive spraying period. 



Third, the strength of solution used. This comes in third place and not first as one 

 might imagine. Lime sulphur 1.005 sp. gr. will do more damage wrongly applied than 

 lime sulphur 1.01 sp. gr properly applied. 



Fourth, the variety of apple. Some varieties, such as Mcintosh, will stand a very 

 strong solution, while Baldwin and Ribston injure very easily. 



Fifth, the amount of sunlight. The effect of sunlight previous to spraying has been 

 fully dealt with in the early part of this paper. 



Sixth, the humidity of the atmosphere. This determines the rapidity with which 

 the solution dries on the trees. The longer the solution is on the leaves the greater will 

 be the injury. Also the more frequently the dry spray material is brought into solu- 

 tion, the greater will be the injury. 



Seventh, whether the tree is loaded with fruit or comparatively empty. A loaded 

 tree will not stand as much nor as strong spray as one of the same variety that is not 

 full of fruit. 



Eighth, whether a tree is in sod and growing slowly, or is diseased in the trunk or 

 root. The more thrifty a tree is, the greater is its resistance to injury. 



Ninth, V. D. Safro in Research Bulletin No. 2 of the Oregon Agr. College Expt. 



