NOTES FROM THE BIOLOGICAL DEPARTMENT, O. A. C. 



223 



potash whale-oil soap, and kerosene were 

 first used with success in large operations. 

 Contradictory results, however, were often 

 obtained by different experimenters, and 

 even by the same experimenter, results 

 which could not be satisfactorily explained. 

 For example, in the hands of some fruit- 

 growers pure kerosene proved beneficial, 

 while in the hands of others it was deadly 

 to the trees. Crude petroleum, too, gave 

 conflicting results, but when a straight par- 

 affin crude petroleum, having a specific 

 gravity test of 43 degrees or over on 

 Beaume's oil scale, was used by Dr. J. B. 

 Smith, of New Jersey, uniform success at- 

 tended the application. It seems that the 

 term " crude petroleum " is applied commer- 

 cially to a great variety of unrefined oils 

 widely different in their compositions, hence 

 when used as an insecticide the term should 

 be specific. 



Again, in a recent bulletin, prepared by 

 H. P. Gould, of Maryland, the reason for 

 so many failures with kerosene is plainly 

 stated. Mr. Gould shows that 20 per cent, 

 kerosene cminot be used on peach trees when 

 they are perfectly dormant without serious re- 

 sults ; but that, as soon as the activities of 

 the tree begins in spring, spraying with 20 

 per cent, kerosene should be commenced ; 

 that there is no necessity for using a stronger 

 mixture than the 20 per cent. ; and that 

 peach trees may be sprayed with the 20 per 

 cent, mixture with comparative safety dur- 

 ing the summer when the young are crawl- 

 ing. 



It is interesting to note that the results 

 secured by Gould coincide largely with those 

 obtained in the series of experiments carried 

 on during January and February, 1900, by 

 Mr. G. E. Fisher and myself, and by Mr. 

 Fisher later on in the season. My notes on 

 these experiments, based on a study of the 



winter buds and San Jose Scales while the 

 trees were still dormant, bring out the fact 

 that in nearly every case the buds of the 

 trees — apples, pear and plum, as well as 

 peach — were destroyed when 20 per cent, 

 kerosene and water was used. 



Mr. Fisher, in his report of the Inspector 

 of San Jose Scale for 1900, states : " As a 

 winter treatment I regard kerosene as being 

 more liable to injure trees than any other 

 remedy with which I have acquaintance. It 

 is not so fatal to fruit buds as soap applied 

 in early winter, but so far as has been ob- 

 served the effect on trees was almost in- 

 variably disastrous. It was used in a me- 

 chanical emulsion in the proportion of 20 

 per cent, with water, which was not so ef- 

 fective as an insecticide, and cannot be said 

 to do even satisfactory work in killing the 

 Scale." 



The conclusions reached by Mr. Fisher 

 regarding the value of 20 per cent, kerosene 

 as an insecticide appear at variance with 

 that of Mr. Gould, but it may be noted that 

 Mr. Fisher did no spraying while the trees 

 were active, and Mr. Gould does not report 

 the effect of the kerosene on the Scale while 

 the trees were dormant. 



Regarding crude petroleum, Mr. Gould 

 summarizes his results: 



1. Crude petroleum seems to be effective 

 in controlling San Jose Scale when properly 

 and intelligently used. 



2. Either a green or amber-colored oil 

 may be used, provided it has a specific 

 gravity of not less than 43 degrees at a 

 temperature of 60 degrees Fahr. 



3. It can only be used when the trees are 

 dormant. In this respect crude petroleum 

 and kerosene act directly opposite. (This 

 applies especially to peach trees.) 



4. It may be used either undiluted or in 

 the 20 or 25 per cent, mixture. 



W. LOCHHEAD. 



