THE XIXETEENTH ANNUAL MEETING. 109 



"In July last, Prof. Forbes piiblislied results o£ experiments, and states 

 that 'there can certainly be no further question of the liability of the 

 curculio to poisoning by very moderate amounts of either London purple 

 or Paris green.' 



"In August last, Prof. Cook published his third group of experiments, 

 which confirm his former results. He remarks, however, that 'in the case 

 of very frequent rains the jarring method will not only be cheaper, but 

 more effective.' The last report of the U. S. entomologist records tests by 

 both Professors Alwood and Osborn. Both experimenters found that the 

 spray checked the ravages of the curculio. Alwood's tests were made upon 

 Green Gage plums, and Osborn's were made in Iowa upon several varieties 

 of native plum. 



"These experiments all go to show that spraying for the curculio is a 

 success. It is not to be expected, however, that such signal results can be 

 obtained here as upon the codlin moth. The codlin moth deposits its 

 eggs in the eye of the fruit, while the young apple is still erect. The 

 poison lodges in this cavity and the young larvae is at once destroyed. 

 The curculio, on the other hand, punctures the side of the fruit, and most 

 of the fruits upon which he works have smooth skins. It is, therefore, 

 more difficult to place the poison at the point of operation. Yet it is no 

 doubt true that the insects are killed by the poison upon the 'leaves as well 

 as by that upon the fruit. 



APPLICATION TO THE PEACH. 



" Until the present season, experimenters have not turned their attention 

 to the peach. But during the past two years fruitgrowers in various parts 

 of the country have sprayed peach trees, and for the most part they have 

 injured their trees. This fact has opened again the question of the proper 

 strength of the spray. Cook has published the best experiments in this 

 connection. He finds that ' London purple is more injurious to foliage 

 than is Paris green ; and white arsenic ( arsenious acid ) is more harmful 

 than either. This is doubtless owing to the soluble arsenic, which is quite 

 abundant in London purple and almost absent in Paris green.' I have 

 observed the same in recent experiments. As j^each foliage is especially 

 susceptible to injury, it is advisable to use only Paris green upon it. For 

 economic reasons, as well as to avoid injury to foliage, the recent tendency 

 is toward weaker mixtures. It is probable that a pound of poison to 250 

 gallons of water is strong enough for any use, while for the peach, and 

 other trees particularly liable to injury, a mixture of half this strength is 

 best. It is always necessary that the spray should be fine, and that it 

 should be driven into the tree with great force. The arsenites are likely 

 to vary in their composition, London purple especially so, it would seem, 

 and more exact directions can not be given. It is always best to err on 

 the side of safety and make a mixture too weak rather than too strong. 

 The common tendency seems to be quite the reverse of this, however, par- 

 ticularly if I may judge by the manner in which various Michigan growers 

 have acted upon my advice during the present season. If the application 

 is very thoroughly made, a weak mixture will kill more insects than a 

 strong one which is carelessly apj^lied. 



SOMETHING DUE TO CLIMATE. 



" There is some evidence to show that climate or latitude has something 

 to do with the manner in which arsenites act upon foliage. Experi- 



