78 N. S. ENTOMOLOGICAL SOCIETY 



leaves due to the use of lime sulphur 1 to 40 in the station orchard. The dwarfed leaves 

 showed no lesions of any kind. They had not been burned by the spray. The damage 

 must have been small. Hertzell (N.Y. State Sta. Bull. 331:580) has described a dwarfing 

 of grape berries which he attributes to lime sulphur with which the grapes had been 

 sprayed." 



The dwarfing of the leaves noted has been observed to follow the first spraying of 

 lime sulphur almost invariably in Nova Scotia, 1.004 sp. gr. lime sulphur is the weakest 

 that has been observed to cause this dwarfing or curling on Gravensteins. The amount 

 of dwarfing from the first spray increases definitely and regularly as the sulphur in 

 creases in strength. We have been able to trace no ill effects from the dwarfing follow- 

 ing the first spray of lime sulphur. In the Proceedings of the Entomological Society of 

 Nova Scotia No. 2, for 1916, page 17, "The Effect of Certain Combinations of Spray- 

 ing Materials on the Set of Apples" by G. E. Sanders is given and is a review of 

 the work of the laboratory in connection with the removal of fruit by spraying. It is 

 noted that where arsenate of lime is used with lime and sulphur more fruit was produced 

 and less burning resulted than where arsenate of lead was used. This was corroborated 

 in 1917, more fruit and less leaf burning resulting from the use of lime sulphur and arsen- 

 ate of lime than from the use of lime sulphur and arsenate of lead. In one respect the 

 work of 1917 differed from that of 1916, the fourth spray of arsenate of lime and lime 

 sulphur in many cases caused yellowing of the foliage that was absent where arsenate of 

 lead and lime sulphur was used. This is the result of adding too much arsenate of lime 

 in proportion to the amount of lime sulphur used, and can be entirely eliminated by the 

 addition of ten pounds of hydrated lime to 100 gallons of the lime sulphur, arsenate of 

 lime solution, thus preserving in the spray the good qualities of arsenate of lime and 

 nullifying its one defect. 



It was assumed in the spring of 1916 that too strong lime sulphur had been the 

 cause of the dropping of the fruit and experiments were planned to determine, first, at 

 what strength lime and sulphur could be safely used, second at what periods it caused in- 

 jury, and third if a substitute could be found which could be used without causing the 

 same dropping of the fruit. 



In general the results of 1916 showed that lime sulphur 1.007 sp. gr and stronger 

 with arsenate of lead and 1.008 sp. gr and stronger with arsenate of lime would cause se- 

 vere leaf injury and dropping of the fruit, that all lime sulphur down to 1.004 sp. gr. 

 would cause slight reduction in the quantity of apples produced, and that the greatest 

 reduction in crop came from the lime sulphur applied as a fourth spray, less from the 

 third spray, less again from the second, while no appreciable injury resulted from the 

 first or deferred dormant spray. It was found that Bordeaux and soluble sulphur, or 

 sodium sulphide, did not cause the fruit to drop to such an extent as lime sulphur, al- 

 though in many cases the leaf injury from soluble sulphur was more noticeable than 

 from lime sulphur. 



With this information we started the season of 1917. We knew that we could cause 

 the apples to drop from trees by spraying them with strengths of lime sulphur usually 

 recommended. Whether it was caused by the lime sulphur burning the fruit, the stems 

 of the fruit, the leaves, or the stems of the leaves, we did not know. We were working 

 with the idea in mind that leaves do not absorb spraying material, but there was a safe- 

 ty point in dilution below which lime sulphur is absolutely harmless to foliage and that 

 lime sulphur in common with all spraying material should be sprayed up, down and in 

 every other direction possible in order to thoroughly wet the whole surface of the tree to 

 be effective. 



Our first problem in 1917 was to find out if the dropping of the young fruit was due 

 to injury to the leaf, or injury to the fruit. To determine this all the apples on a branch 

 of a Gravenstein tree were covered with lime sulphur 1.01 sp. gr. by means of a brush, 

 and the leaves left untouched. On another branch the apples were covered with small 

 caps, thus protecting them from the spray, and the leaves alone were sprayed by means 



