13 



Injury to Foliage. 



" The greatest drawliack that has heretofore been experi- 

 enced by those who sprayed with the arsenites is the danger 

 of injuring the foliage, — ' scorching' or 'l)urning' it as is 

 generally said. This may be guarded against by using 

 weak mixtures, keeping the liquid well stirred and applying 

 evenly ; and it is pretty well proven that it is safer to apply- 

 on a cloud}' day or late in the afternoon, than during the hot 

 sunshine of midday. Of course especial care must be taken 

 to keep all poisons out of the reach of children and stock." 

 (Bulletin, Vol. III., No. 4, Ohio Agricultural Experiment 

 Station, Weed.) 



" That forcible spraying does, in ordinary cases, damage 

 foliage worse than gentle spraying I have no doul)t, l)ut I 

 believe the reason for it to be found in the fact that the 

 leaves are more thoroughly treated in the former case than 

 in the latter." (Bulletin No. 2, Iowa Agricultural Experi- 

 ment Station, Gillette.) 



" I think we are warranted in the following conclusions : 

 First, London purple is more injurious to the foliage than is 

 Paris green ; and white arsenic, arsenious acid, is more 

 harmful than is either London purple or Paris green. This 

 is doubtless owing to the soluble arsenic which is quite 

 abundant in London purple, and almost absent in Paris 

 green. 



" Secondly, Peach foliage is especially susceptible to in- 

 jury, and cherry foliage the least so of any of the kinds 

 (plum, cherry, apple, willow, elm, maple, pear, peach) 

 treated. 



" Thirdly, It would seem that London purple and white 

 arsenic, used just before a rain, are more harmful than when 

 used during a drought. This also accords with the view 

 that the injury comes from the presence of soluble arsenic. 



" Fourthly, It would seem that spraying soon after the foli- 

 age puts out is less harmful than when it is delayed a few 

 days, or, better, a few weeks. 



" Fifthly, London purple may be used on apple, plum, 

 cherry, pear and most ornamental trees, but on these should 

 never be stronijer than one i)()und to two hundred gallons of 



