96 THE REPORT OF THE [ No. 19 



mechanical 20 per cent, emulsions of either kerosene or crude petroleum, also of similar 

 25 per cent, emulsions. Other photographs showed positive injury from the use of un- 

 diluted kerosene, and most marked injury from undiluted crude petroleum ; one plum tree 

 was killed outright by the latter treatment. 



Experiments undertaken in other localities also served to show that crude petroleum 

 may seriously injure trees under certain conditions. The trees may eventually outgrow 

 the harm, and it is possible that the injury may be no greater than the scale would have 

 caused, if allowed to go unchecked. The mechanical dilutions of crude petroleum, at 

 least up to 25 per cent., appear to be harmless if applied before the buds are open, and it 

 is to be hoped that they will prove effective in controlling the scale. 



A general discussion followed the reading of Mr. Felt's paper. Mr. Scott said that 

 in Georgia undiluted crude petroleum killed peach and plum trees outright, but 50 per 

 cent, and less strength did very little damage. The best results were obtained with 25 

 per cent, in mechanical mixture with water sprayed with a Gould kero water sprayer. 

 The application was made just before the fruit buds opened in the spring ; all the insects 

 reached by the spray were killed, according to notes made up to June 12, Until that 

 date the sprayed trees remained oily and the odor of the crade petroleum could yet be 

 detected. It is a reasonable conclusion, then, that the scale can not live so long under 

 such a coating of oil. He had concluded that the 25 per cent, crude petroleum in 

 mechanical mixture was better than refined kerosene of the same strength. 



Mr. Woodsworth said that when the bulletin from the New Jersey station came out 

 it was heralded all over Oalifornia, and he had to write more letters in rpgard to the kero- 

 sene and crude petroleum treatment than about any other insecticide. Crude petroleum 

 in California is a very indefinite term, since there is a crude petroleum from Ventura 

 which is as thick and black as molassr s, and from that it varies to crude petroleum which 

 is almost as thin as gasoline. Even in a single well the product varies according to depth 

 and ag», and distillations show that it varies greatly in composition. He had been assured 

 that the Eastern product varied also, and was of opinion that before we can recommend 

 any percentage of crude petroleum we will have to establish a criterion of excellence. 

 The difi'erent kinds of crude petroleum he had experimented with in California produced 

 very different results — strikingly different. There is also a very decided difference in 

 results according to time of spraying with the same oil. Thus spraying before rain and 

 after rain may produce entirely different results. He had sprayed with gome forms of 

 crude petroleum without injury which would have thoroughly destroyed the foliage at an- 

 other time of day. The amount of water in the leaf may determine to a certain extent 

 the damage by the oil. It seemed to him, therefore, that another thing that must be 

 done before we can really properly understand the action of the oil will be to study the 

 effect of the oil upon the vegetable tissue. Perhaps this had already been done, but it 

 was still in large part a mystery to him. 



Mr. Webster said he had used oil from two wells located in different parts of Ohio 

 this year, and although the analysis ran almost exactly the same in each case the effect 

 has been different. In the one case he had not seen the orchard for several weeks, but 

 when he last saw it the peach trees seemed to have been in many instances killed by the 

 use of crude petroleum. He could not say whether the oil had been applied just before 

 or just after a rain. In the other case the trees sprayed were seedling apples on the ex- 

 periment farm, the experiment being made to determine if possible the effect upon the 

 trees and not against insects. Some of the trees leaved out at the proper time about as 

 freely as usual, while others had no leaves at all. At the present time, however, there 

 was no apparent difference whatever in them, all having finally leaved out precisely the 

 same. It was evidently nothing but a temporary injury. His experiments had pro- 

 duced such various results that he was badly mixed up and did not favour recommending 

 the use of kerosene of any sort. He was of the opinion that the variation would be just 

 as great in the crude article as in the refined. 



Mr. Hopkins said that in West Virginia they have a great variety of petroleum, 

 from that as thick and black as molasses to the thin light- coloured product. The oil ob- 

 tained from the Standard Oil Codipany is a mixture of all kinds except the heavy oil. 

 The heavy oil is used for lubricating machinery. He had obtained some results which are 

 quite at variance with the testimony of others and show what conflicting results can be 

 obtained in different States. In one case he recommended crude petroleum as an experi- 



