64 MAINE AGRICULTURAL LXPERIMLNT STATION. I913. 



spray injury was 23lainly evident on the foliage. This was, 

 however, frequently plainly associated with scab spots and sug- 

 gested that it might be analogous to arsenical injury on potato 

 leaves which have been injured by flea beetles. A given amount 

 of Paris green or other arsenical may be used on potato plants 

 with perfect safety so long as the epidermis of the leaves is 

 unbroken. On the other hand, if a considerable number of flea- 

 beetle punctures are present in tlie leaves arsenical injur}' is 

 quite likely to result, the severity of the injury varying with the 

 number of punctures. 



By August I the evidence of scab infestation on this plot had 

 largely disappeared and no increase of the amount of spray 

 injury on the foliage was observed during the remainder of the 

 season. 



Plot C sprayed with i 2-3 gallons of lime-sulphur and 2 

 pounds of arsenate of lead diluted to 50 gallons. Detailed 

 records made of the amount of scab on the leaves of the indi- 

 vidual trees in this plot at various times during the season 

 showed relatively more scab was present than on plot B, where 

 the "one-fifth stronger" dilution of lime-sulphur was used. On 

 the other hand very little leaf-spot or spray injury was observed 

 on plot C. 



Plot D, sprayed with i 1-4 gallons of lime-sulphur and 2 

 pounds of arsenate of lead diluted to 50 gallons. Much more 

 scab was observed on this than on any of the other lime-sulphur 

 plots. Judging from the appearance of the leaves alone, and in 

 comparison with plot E the two applications of this weaker 

 dilution of lime-sulphur failed to exert any restraining influence 

 on the development of the scab fungus whatever, although it 

 will show later that it did reduce somewhat the amount of scab 

 on the fruit. 



Plot E, sprayed with 2 pounds of arsenate of lead in 50 gal- 

 lons of water. With the exception of plot D this showed the 

 greatest development of scab on the foliage of any. In this 

 connection it should be noted that there was a decidedly less 

 amount of sca'b on the leaves of the trees in plot A where double 

 the amount of arsenate of lead was used without any lime-sul- 

 phur. In fact on the last mentioned, considering plot E as a 

 check, the control of scab on the foliage w-as fullv equal to that 



