82 N. S. ENTOMOLOGICAL SOCIETY 



on foliage conditions which are not usually brought about by previous bright sunshine 

 while only the three last answers are in any way free from the hint that the injury fol- 

 lowed periods of darker weather than usual. 



On page 479 of the N.Y. Exp. Sta. Bull. No. 330, Parrot and Schoene state, "Cord- 

 ley (A. B. Cordley, "Better Fruit" 8:34) suggests that, "abundant sunshine and 

 mild temperature produces a vigorous hardy spray resisting growth of foliage, while 

 excessive rainfall, cloudy weather and low temperature produce a growth, less vigorous, 

 less hardy and more edematous and more susceptible to spray injury. During cloudy 

 and humid weather evaporation is also less rapid and the foliage is consequently longer 

 exposed to drops of the spray of injurious densities." 



Again, "During 1909 and 1910 J. P. Stewart (Letter Dec. 7th, 1910) also noticed 

 that varieties differed in degree of susceptibility and that there was an apparent sea- 

 sonable difference in varietal resistence." 



On page 477 the same authors note, "Such injury (serious) has been noted once in 

 experiment No. 5 in which the fourth spraying caused considerable defoliation of the 

 trees and dropping of the apples. Of the other experiments No. 3 states that "Applica- 

 tions of the diluted spray, testing 1.5 B, caused considerable injury to the foliage of a 

 number of apple trees, while the larger portion of the orchard was unaffected." No. 4 

 reported, "The spraying after blossoming caused slight burning of the leaves especially 

 on those portions of the trees where the application was heaviest." No. 6 reported, 

 "There was, however, slight burning of the foliage by the second treatment while the 

 spraying to complete the last application caused considerable burning of both fruit and 

 foliage, resulting in a loss of about two-thirds of each." 



We know that the rainfall in Geneva in April 1910 was the greatest ever recorded 

 for that month while the record of rainfall for May of the same year was only slightly 

 above normal. There is no record of sunshine at hand. 



It has been noted by Mr. Paul A. Murphy of the Dominion Division of Botany 

 and by Mr. F. H. Johnson, of Bridgetown, N. S., that lime sulphur usually injured the 

 north side and the centre of the apple trees more than the south side. This might in- 

 dicate that the chlorophyll may be so depleted by dark weather that the slightly varying 

 amounts due to the difference in the amount of light on the north side and the south 

 side of a tree may mean the difference between burning and no burning. 



The increased use of high pressure spraying outfits has undoubtedly been a factor 

 in increasing lime sulphur injury. When the use of lime sulphur first became general, 

 in 1910, 1911 and 1912, a large portion of the spraying was done with hand outfits, or 

 low pressure power outfits. As the orchards increased in size it became nescessary to 

 use more power outfits with higher pressure and larger capacity nozzles, with the result 

 that more spray was applied to the tree, and more particularly to the under side of the 

 leaves. In 1917 about 225 spray guns were used in the Annapolis Valley, the operators 

 usually using them from the ground and thus wetting the under more than the upper 

 side of the leaves. It can be easily understood how these changes in methods of spray- 

 ing have been factors in increasing lime sulphur injury. 



It has often been contended that moisture has been the cause of increased injury 

 from lime sulphur. While we are convinced that spraying when the trees are wet or 

 the air humid will result in increased burning, we are not at all sure that moisture is as 

 important a factor in lime sulphur injury as it is commonly supposed to be. 



