234 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



age of the aphids, but it is interesting to note that the potato aphis proved, 

 in our experiments, to be more resistant to dust mixtures with nicotine 

 than the apple species. Preparations with two percent, nicotine are 

 expensive, and the cost makes the treatment impractical except for 

 experimental operations. In addition to encouraging improvements 

 in machinery^ experimental workers should lend their efforts to the pro- 

 duction of cheaper insecticides and fungicides in dust form. The 

 future progress of dusting truck crops depends to a large extent on the 

 solution of these problems. 



President W. A. Orton : We have to deal not only with the potato, 

 but other crops. Spinach blight, so-called, is a mosaic disease very 

 prevalent in Virginia, Ohio, and other states. The aphis spreads the 

 spinach mosaic and ought to be controlled. Cucumber mosaic, the 

 principal limiting factor in the pickle industry of the Great Lakes States, 

 is spread mainly by aphids. If we can have effective methods of aphis 

 control of cucimibers, we can pretty nearly revolutionize the cultivation 

 of cucumbers for pickles. Potato mosaic is getting more abundant 

 every year and new hosts of mosaics are constantly brought to our atten- 

 tion. It is likely that there is insect transmission in all cases, conse- 

 quently the men who are experimenting with means for destroying 

 aphids have a big work cut out for them, and an opportunity to do a 

 very large service in the control of plant diseases. 



Mr. McClintock : I would like to ask the entomologists a question. 

 Certain agents, who are selling dusts at the present time for the control 

 of insects in peaches, state that the sulphur in the dust has some repellent 

 action as far as curculio are concerned. I would like to have that ques- 

 tion answered, and further if there would be any advantage in a dust, 

 in having the nicotine, as a repellent to the curculio. 



Mr. a. L. Quaintance: I think that dust on the peach tree might 

 have some repellent action. I don't think it would be sufficiently repel- 

 lent to afford protection from the curculio. I doubt if the nicotine would 

 be of ver}^ much value, not enough to warrant its cost. The treatment 

 for curculio is arsenate of lead. 



Mr. L. R. Taft: We were very properly warned by the Chairman 

 against stating premature conclusions. I wish to state my conclusions 

 after thirty years' experience with dusting and spraying carrying them 

 on in an experimental way, and also watching the results obtained by 

 practical fruit growers. 



I am convinced that in Michigan, at least, we can get practically as 

 good results against curculio and the codling moth with the arsenical 

 dusts as with the ordinar}^ sprays, but we fail when using dust against 



