164 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



followed. It is well, however, to cease spraying just before a freeze 

 is predicted. It is well known that neither hot sun, nor shade, neither 

 rain nor dry weather existing either during or following the application 

 is influential in causing damage. 



As yet no experiments have been conducted to determine the effect 

 of these sprays on the bloom and it is inadvisable to use them during 

 the blooming period. 



It has been observed that the use of these oils, including kerosene 

 emulsion, causes dim shadows or faint green blotches to appear on 

 the fruit if sprayed early in the season. These disappear when the 

 fruit colors up in the fall and this has never been considered a serious 

 matter by the author. 



Mr. H. J. Quayle: I agree with Mr. Yothers that the injury may 

 be due to something other than the oil itself. We depend largely 

 on distillate oils in California and they are used at a strength from 

 6 to 8 per cent on dormant trees. The latest use of oil there is the 

 heavy crude petroleum, 16° to 18*^, just as it comes from the wells 

 and is used in the form of an emulsion with soap at a strength as 

 high as 15 per cent. This seems to be the only thing that will control 

 the Italian Pear Scale successfully. Thus far there appears to be 

 no complaint of injury even with the heavy crude petroleum. 



Mr. H. a. Gossard: A number of years ago I conducted some 

 small experiments with oils, obtaining the same results as stated by 

 Dr. Felt. Trees treated in the fall had some of the fruit buds killed^ 

 while no injury was done by spring applications. The manufacturers 

 of the oil were quite perplexed and skeptical concerning my conclu- 

 sions and went to considerable trouble to determine where the trouble 

 lay. They took samples of the water used for diluting the oil and 

 reported that they found considerable sulfur in it. They thought 

 this was the explanation of the adverse result. Referring to spray- 

 ing mixtures, I prefer to recommend the preparation that is nearest 

 to "fool-proof" of any that I know. If I am writing to an experi- 

 enced horticulturist, whom I know to be an intelligent sprayer, I 

 use my best judgment in giving a prescription, but when making 

 general recommendations for publication or when writing to strangers, 

 I always want to name the nearest to a "fool-proof" remedy that 

 I can. For this reason I prefer to recommend home-made lime- 

 sulfur solution where practicable before the oils or the commercial 

 mixtures. 



Mr. T. B. Symons: In the case of peach lecanium the lime- 

 sulfur will not phase it. We have to recommend the use of an oil 

 mixture, but we state that the application should be made as late 

 in the spring as possible. 



