April. '09] JOURNAL OF ECONOMIC ENTOMOLOGY 147 



most of the work was done, and that his work in the field was there- 

 fore limited to one or two hasty trips. It is also well to remember that 

 no experiments were carried on on fruit trees, the only attempt to 

 test the effect of arsenic being- made on green-house plants, and that 

 the only trees known to have died from arsenical poisoning Avere the 

 two that were killed by the solulile arsenite of soda, which we know 

 would have killed them innnediately if it had been sprayed on the foli- 

 age. 



Mr. Carpenter, a former resident of this valley, is authority for the 

 statement that the waters of the Grand River carry a considerable 

 amount of soluble arsenic, received from the washings of mines and 

 smelters located upon its head waters, and that at the present time 

 arsenic can be found in all the soils of the lower end of the valley. 

 This may possibly be the source of some of the arsenic found by Doc- 

 tor Headden, rather than from the insoluble compounds used in spray- 

 ing. 



Where the Bulletin is Valuable 



This bulletin, if rightly interpreted, contains considerable of value 

 to the fruit grower. This interpretation, however, will be one of ver\" 

 guarded warning against intemperate and excessive as well as needless 

 use of arsenicals. Thus construed it will only serve to strengthen the 

 position taken by those who are urging the use of the new methods in 

 spraying, worked out by the Utah Experiment Station and later con- 

 firmed by other workers. For in these experiments it has been 

 abundantly' proven that one single driving spray, if applied at the 

 right time and in the right way, will do more to protect an orchard 

 for the entire season than half a dozen sprayings in the old way. 



Doctor Headden shows in his bulletin that even a small amount of 

 ordinary alkali, or even of common salt alone, in the water will serve 

 to render some of the arsenic of a spraying solution soluble, which 

 serves to explain a number of things that have happened in Utah in 

 the past. In one case an orchardist sprayed his entire orchard with 

 Paris green and practically ruined his crop by burning, while his 

 neighbors used the same brand of poison without serious injury. This 

 particular orchardist. however, undoubtedly used strongly alkaline 

 water from a surface well, while his neighbors took their water from 

 an irrigation ditch. 



In another case an orchardist used an approved brand of lead ar- 

 senate in spraying and killed everything that he touched with it. It 

 was only a small job and it seems probable that the barrel used had 

 formerly contained salt or brine. 



This bulletin will also serve as a warning to those contemplating 



