April, '15] 



ENTOMOLOGISTS' PROCEEDINGS 



169 



the variatioiis in apples due to differences in environment. I hope 

 later to add more to this phase of the question. 



]\Ir. W. M. Scott: There is another question that Mr. Parrott's 

 paper raises and that is the question of pressure. I think that we 

 have been somewhat extreme on that point. The spray pump people 

 have vied with each other to put out machines that would give the 

 highest pressure and deliver a large quantity of material per minute. 

 The result has been, according to my observation, injury to fruit and 

 foliage by an excess of spraying material in the first place, and in the 

 second place (and I think not an unimportant point either) by actual 

 mechanical injury from driving spray under high pressure. 



I have been knocking around over the country quite extensively 

 in the last couple of years, looking into just such matters, and I fre- 

 quently find apple crops injured by arsenate of lead and lime-sulphur 

 solution. Upon making inquiiy I find that most of that injury is 

 found in orchards where high-pressure machines have been used. 

 Professor Quaintance and I, a few years ago, conducted a cooperative 

 experiment in the use of lime-sulphur solution and arsenate of lead 

 in spraying apples under high pressure. I think we had 300, possibly 

 350, pounds pressure and on the trees that we sprayed under that 

 pressure, the foliage was badly injured and the fruit badly burned— 

 to the extent perhaps of 50 per cent loss of the crop. Whereas the 

 adjacent trees sprayed with the ordinary outfit, using the mist type 

 of nozzle, did not show the injury — or at least not very much of it. 



I think that is a point we ought to bear in mind in recommending 

 applications with high pressure machines. 



Mr. E. G. Titus: In Utah it appears that 125 pounds is suffi- 

 cient so far as pressure is concerned. The ordinary barrel pump will 

 give sufficient pressure with the ordinary driving spray and will give 

 better results than a 300-pound pressure outfit. It has been done 

 many times. So far as penetration is concerned, we can penetrate 

 with this pressure in a very high percentage of cases. In some recent 

 experiments against the fruit-tree leaf roller, in which the question 

 of the codling moth came in, I had no trouble at all with an ordi- 

 nary barrel pump in getting less than one-tenth of one per cent calyx 

 wormy, and less than five per cent side worms in the orchard, and I 

 am certain that we did not get a hundred-pounds pressure. On 

 another orchard we used a power pump, but didn't attempt to get 

 over 150 pounds at any time — I do not think it is necessary. The 

 very high pressures not only injure the apples, but they actually 

 blow some blossoms right off the limbs. 



Mr. Watkins: Perhaps you would like to know the pohcy of the- 

 University of Uhnois. For five years we have been recommending 



