28 MISSOURI AGRICULTURAL EXPERIMENT STATION BULLETIN 177 



that nursery stock can stand a solution of lime-sulphur a little stronger than 

 1-9 without any additional injury. 



Neither did the lime-sulphur have any effect upon the roots of the 

 plants which were treated in 1915, for in only one case, the 1-9 solution 

 where both roots and tops were dipped, was the percentage of dead plants 

 greater than when tops only were dipped. Of these plants treated with the 

 1-7 solution, the percentage of dead was greater in the set treated tops only. 

 In 1920 the results were different and the plants that were dipped both tops 

 and roots suffered a much higher mortality than those dipped tops only. 

 All of the plants trea-ted with both the lime-sulphur and miscible oil were 

 dipped instantaneously. If the plants had been allowed to remain in the 

 solution for 5 or 10 minutes or longer there would have probably been a 

 greater difference in the results obtained. 



The 1-9 solution gave better results in Controlling the scale than the 

 1-7 solution, so taking everything into consideration it seems that just as 

 good results could be obtained by using a 1-9 solution upon nursery stock 

 for the control of scale, as a 1-7 solution. However, owing to the fact that 

 none of the sulphur compounds killed all the scale and that considerable 

 injury may result from their use upon young plants it seems advisable 

 according to these experiments, to discourage the use of them as a dip. 



MISCIBLE OIL FIRST USED 



In a paper which appeared in Marseilles, France in 1763, petroleum, 

 turpentine and other oils were recommended for killing plant lice. In this 

 country turpentine mixed with earth and water was used to destroy worms 

 in trees as early as 1835 and in 1865 kerosene was recommended for destroy- 

 ing scale on orange trees and was successfully applied to oleander, sago- 

 palm, acacia and lemon trees. The oil was applied by means of a feather. 

 In June 1866 kerosene was recommended, in Gardener's Monthly, for de- 

 stroying all insect life. Later it was found that kerosene and other oils 

 mixed better with water if a soap was added and the material could be 

 applied with a syringe. It is not definitely known who made the first kero- 

 sene emulsion but about 1875 kerosene mixed with soap was first used. 



Use up to present time. Since 1875 many different mixtures containing 

 miscible oils have been recommended for the destruction of both chewing 

 and sucking insects, particularly the latter. Petroleum oils and soap form 

 the basis of many patented miscible oil solutions which can be purchased 

 on the market today. The miscible oils kill the insect by contact. The oil 

 has great penetrating ability and probably kills the insect by preventing the 

 assimilation of oxygen in the tissues. 



The following are some of the most common and most widely used 

 of the miscible oil insecticides. 



Kerosene 2 gallons 



Soap Vz pound 



Water 1 gallon 



Dissolve the soap in hot water, remove from fire and while still hot 

 add the kerosene. Th emixture is thoroly agitated for five or ten minutes 

 or until it becomes a creamy mass. Crude oil can be substituted for the 



