THE MONTHLY BULLETIN. 403 



spray tank with arsenate of lend and soap, the high per cent of damage seemed due 

 more to the orchard condition, variety of apple and method of application, than to 

 the material. Orchards numbered lit. 115 and lit! were sprayed with dry sulphur 

 also, but with very little injury. In looking over tin- table you will not find a ease 

 where arsenate of lead either alone or with soap caused any appreciable injury. 

 On the other hand orchards numbered 07. (JS, 69 and ll!» did not have soap in any 

 form and the injury was great. Orchards numbered 57, 00, 62, 81, 82, 83 and 102 

 all furnish good illustrations of where sulphur was used on part of the orchard, but 

 not on the entire orchard. In these eases the work was done by the same outfit on 

 the same day, but with considerable difference in results. 



In the case of orchards numbered 67, 68 and 69 no soap was used, and in 

 67 arid 69 the sulphur was decidedly below strength, still the injury was severe. 

 These few instances will serve to show that the sulphur was the element which 

 seemed to cause the injury. Many other equally interesting instances could be 

 shown of variations due to orchard conditions, locations and vitality of trees if 

 space permitted. 



From a careful study of the facts as they appeared it seems that there is an 

 element of danger in the use of sulphur in any form during the growing period. 

 This spraying was all done under favorable conditions which continued for several 

 days. The arsenate of lead-sulphur-soap spray seems fairly safe in dry climates, 

 provided the temperature does not exceed 100 degrees ; above that temperature 

 there seems to be an element of risk. Orchards in the lower valleys either sprayed 

 or unsprayed where the temperature was 5 to 8 degrees higher were burned. Thi.s 

 indicates that all orchards, sprayed or unsprayed, were very near the point of 

 damage from excessive heat and that in some cases the sulphur proved just enough 

 to cross this line. 



Another quite noticeable feature is that the most severe burning occurred on 

 orchards where the vitality of (he trees was low. This might have been caused by 

 poorer soil, lack of proper moisture or other unfavorable soil conditions. Two of 

 the worst burued orchards had not been plowed, and consequently were dry. 



From the table on pages KM -407 it seems quite certain that this injury was caused 

 by a combination of conditions, namely, sulphur, lack of tree vigor ami heat. 



