18 N. H. AGE. EXPERIMENT STATION. IBulletin 183 



spray material did not result in as large an amount of spiay ad- 

 hering to the surface of the apple as could be secured by applying 

 a mist-like spray to the surface. When the apple was dipped 

 there was more tendency for the material to run off. When a 

 fine spray was applied to the surface and the application was 

 stopped before the drops coalesced, a maximum coating was 

 secured. It should be noted that the stem end of the apple was 

 not filled up with poison. The spray material was used in a 

 concentration equiv^alent to 6 lbs. of arsenate of lead paste to 50 

 gallons of water. 



The first lot was Baldwins, picked in the fall and treated in 

 December. The test showed 665 apples required to use up one 

 gallon of spray material. Translated into other figures this 

 means 9.6 grams of white arsenic to 665 apples, or 4 milligrams per 

 apple. Thus.it will be seen that each of these apples carried five 

 to eight times the amount found as the maximum in the case of 

 fruit picked from sprayed trees. On the other hand the apples 

 were so obviously coated with spray material that one could not 

 be unaware of their condition (see photograph). Again, the 

 spray here was used at the rate of 6 lbs. to 50 gallons, whereas 

 recommendations for spraying trees in fruit seldom specify more 

 than 3 lbs. to 50 gallons. The latter strength would result in 

 practically half the arsenical residue per apple, since all our ex- 

 periments have shown that with any ordinary concentrations of 

 lead arsenate, after the maximum amount of spray has been 

 applied that will cling to the surface, the residues that will re- 

 main are governed by the concentration of material used, not by 

 the application of larger quantities of spray. 



It seemed possible that the apples used in the above test in 

 December might not fairly represent those on a tree in the fall, 

 through variation in the ability of the skin to retain spray. For 

 this reason another lot was similarly treated in October of the 

 following -j-ear. The results were practically identical: 656 

 apples to a gallon of spray, as compared with 665. 



Again it was possible that a variety with a rougher skin might 

 retain more. Therefore, the test was repeated, using Russets. 

 The results with these were nearly the same: 648 apples to the 

 gallon. 



