STATE HORTICULTURAL SOCIETY. 117 



held, where neither r;iiii nor wiiul could dislodge it, we have ad- 

 ditional reason for this absolute prohibition of the use of any poison 

 dangerous to health excei)t when the fruit is young. 



I made this year some furtber experiments, intended to test the 

 relative efficacy of Paris Green and a solution of arsenic, as applied 

 to the Codling Moth, spraying two trees with the standard arsenic 

 solution, in comparison witii two others sprayed with I^iris Green. 

 The results are shown in Diagram IX, where the broader, heavy 

 bands indicate the effect of thrice spraying with Paris Green and the 

 narrower heavy ones that of thrice spraying with arsenic* The 

 o])en l)ands represent a complete check derived from four trees not 

 sprayed. It will be seen at a glance that, so far as these experiments 

 are concerned, the advantage remains decidedly with the Paris 

 Green. f It will be rememl)ered that I made a similar comparative 

 experiuient last year with Paris Green and London Purple, finding 

 there, also, that the former poison was decidedly the more efficient. 

 As only a single tree was treated with London Purple, and as I see no 

 sufficient rea.so)i wby this substance should not act as efficiently as 

 Paris Green, I think that this result should not be insisted on. The 

 facts, as made out, are illustrated by Diagram X, of which the open 

 bands represent the check tree, and the solid ones that poisoned with 

 London Purple. 



For the purpose of completing this exhibit of our experimental 

 results, I have added Diagram XI, representing the lime experiment 

 of last year. In this the solid bands represent, as usual, the treated 

 tree, and the open ones the check, the damage from the codling 

 moth being actually a little greater upon the tree sprayed with lime 

 than upon its companion. 



I have now merely to recall the results with respect to curculio 

 injuries to the apple, derived from our last year's work, by which, it 

 will be remembered, it appeai'ed that about half the damage done by 

 curculios was prevented by the Paris Green. We kept a similar ac- 

 count of the curculio injuries this season, l)ut their numbers were so 

 completely insignificant as to give us no sufficient basis for compu- 

 tation, neither check nor experimental trees showing usually more 

 than one or two per cent, of injury. It consequently remains for us 

 to determine another year the effect upon curculio injuries of sjiray- 

 ings made only early in the season, while the fruit is small. As the 

 curculio's work is distributed over a much greater interval than that 

 of the first brood of the codling moth, the arsenical poisons, early 

 applied, are much less likely to affect it in any important way. 

 I I think we are justified, however, in this important conclusion: 

 that the incidental benefit to the crop by such protection against the 



• 1 he white arsenic, as analized for me by Prof. McMiirtrie, proves to have been of excellent 

 quality, containiug ninety eiglit iier cent, of arsenious acid. 



t We furtlier noticed a decided scorcliing of the leaves on the trees which were si)ruyed with 

 arsenic, while those to which the I'aris Green were applied were entirely uninjured. 



