52 



repeated during the winter of 1897-98, the applications being made 

 under different weather conditions. In no case had any damage 

 resulted except in the first test, which was conducted on a still day 

 with a very moist atmosphere, the sun breaking through the light fog 

 which prevailed. The trees included peach, apple, pear, and quince, 

 and it was noted that the bark gave evidence of being oily and remained 

 dark colored for a long time, the oil seeming to have soaked in, and did 

 not readily evaporate afterwards. The peach trees included in this 

 first test were all killed to the ground, the apple, pear, and quince trees 

 sustaining no damage whatever. Later tests in bright weather on the 

 same varieties of trees and also on cherry trees did not develop any 

 injury to any of the trees, not even the peach suffering in the least. 

 In this instance, however, the wet or oily appearance of the bark was 

 not noticeable as in the former instance except for a short time 

 after the treatment. He referred to the experience of former years in 

 which diverse results had been obtained, and was inclined to adhere to 

 the ground taken in 1897, namely, that treatment with oil is dangerous 

 and liable to kill the trees or greatly injure them, and its use should 

 never be recommended without calling attention to this possibility and 

 leaving the grower to undertake the work at his own risk. 



Mr. Osborn reported that his experience with pure kerosene as an 

 insecticide was too limited for him to express a decided opinion. From 

 the difficulties encountered in getting a uniform spray in case of windy 

 weather and the varying rapidity of evaporation during different 

 degrees of humidity it would seem as yet unsafe to recommend it gen- 

 erally. In future experiments it would seem desirable to keep careful 

 records of humidity, temperature, wind, and the particular species of 

 plants sprayed, so as to arrive at some sure foundation in case it proves 

 safe under certain conditions. Even then there would be danger that 

 the average orcharclist would not be so careful in securing the necessary 

 conditions as might be required to secure safe results. 



Mr. Howard stated that in view of the diverse experiences given by 

 different speakers, and also shown in the literature of the subject, he 

 felt that the recommendation that he had made in Bulletin No. 12, 

 Division of Entomology, on the San Jose scale in 1896-97, was still 

 pertinent, namely, that it is not advisable to recommend the pure kero- 

 sene spray as the result of any one's experience without first advising 

 the individual fruit grower to experiment in a small way and determine 

 for himself by experience in his own locality and under the local con- 

 ditions that exist there whether he can use kerosene to advantage. 



Mr Johnson stated that his experience with pure kerosene in Mary- 

 land was such that he could not recommend it for spraying young and 

 bearing trees in the orchard, unless done under his own personal super- 

 vision. Even then, he said, he would use the material with reluctance, 

 as he felt sure he was using a substance more disastrous to the life 

 and vitality of a tree than the San Jose scale itself. In all the experi- 



