64 TRANSACTIONS OF THE ILLINOIS 



the use of arsenical poisons has become a necessity to the orchardist, 

 but they should be used with extreme caution. Next season he will 

 use a weaker mixture, about one ounce of Paris Green to fifteen gal- 

 lons of water. 



Mr. J. M. Cunningham, of the same county, speaking of the 

 crop of winter apples, says "they are affected by a rust and other- 

 wise not as smooth as usual. The cause of this defect would re- 

 quire a close investigation, but my opinion is that it is caused by the 

 extreme drouth of last season ; also, I think, aided by the free use of 

 arsenical poisons. I will state why I make this assertion. May 11th, 

 12th and 13th I sprayed my orchard, using one and one-eighth of 

 an ounce of Paris Green to ten gallons of water, spraying the trees 

 till the leaves were thoroughly wet, and am sure that the trees were 

 damaged by the effect of it. One-half of the leaves dropped in 

 from two to four weeks. Other orchards were badly injured by the 

 use of London Purple. In all these orchards many of the apples 

 dropped with the leaves, and the trees grew but little during the sea- 

 son. While I believe these poisons are great insect destroyers,I would 

 advise caution in their use ; for if used as strong as is generally 

 recommended, I believe the trees will be damaged. But what shall 

 we do? Shall we allow tbe insects to destroy our trees and fruit, 

 or shall we fight them with the poison as recommended?" 



Fight them, by all means, even though some danger at+ends the 

 application. I am very sure that ninety per cent, of our fruit can be 

 saved from the codling moth ; that the canker worm can be entirely 

 exterminated, and the curculio kept in check by these poisonous appli- 

 cations. I am also sure that if used tqo strong, or in too large 

 quantities, the leaves will be injured, and with the leaves, the trees 

 and fruit. It has occurred to me that if a strong application, 

 especially of Paris Green, is used it may be an exciting cause of scab, 

 but further experiments will be required to settle this point. 



After a number of careful experiments and considerable obser- 

 vation, I have come to the conclusion that London Purple is less 

 liable to injure leaves and fruit than Paris Green, and that a weaker 

 solution — about one pound to one hundred and fifty gallons of 

 water is sufficiently strong. 



Knowing that Dr. Douglass, of Calhoun county — who is one of 

 the largest and most successful orchardists in the State — had 

 been experimenting with London Purple, I wrote to him, asking for 

 the results of his experiments, intending to incorporate it in the 

 above paper; but, as it came too late to use in that way, I give it 

 entire.as it contains just the information that many orchardists are 

 seeking for. 



