542 Bulletin 78. 



it to carbon bisulphide for he found it just as effective and in no danger of 

 injuring the plants. 



In 1884, however, Mr. Goff experimented vpith an emulsion made of 4 lbs. 

 of soap, I gal. kerosene, and i gal. water. One ounce of this was dissolved 

 in one pint of water and repeatedly applied to the roots of an infested cab- 

 bage plant, with apparently no effect on the maggots. The amount of kero- 

 sene used by Mr. Goff was greater than that used by Prof Cook at each ap- 

 plication. 



In 1887, Prof. Cook applied his emulsion freely 3 times a week to cabbages 

 and radishes ; it seemed to have no effect on the inspect, but in one case it in- 

 jured the plants. He concludes : "that I have killed these maggots both in 

 the garden and on potted plants in the laboratory, by the use of the kerosene 

 and soap mixture. Yet upon a thorough trial I am persuaded that the 

 remedy cannot be made practicable." Mr. H. A. March of Washington 

 State wrote the same year that Cook's emulsion cost him 2000 cauliflower 

 plants. In 1889, Mr. Hulst carried on some experiments with the Riley- 

 Hubbard emulsion which indicated that when diluted with 9 parts of water 

 it injured the plants, but could be safely used when diluted with 12 or 15 

 parts of water and it would then also destroy the maggots. There would be 

 about as much kerosene in a pint of this dilution as Mr. 'Goff had used in his 

 experiment. In 1889, Dr. Riley advised Zimmer Bros, of Alabama to try the 

 emulsion on their cabbages then infested by the maggots. They reported 

 that when diluted with 9 parts of water, it killed every plant ; but when 12 

 parts of water were used in diluting, no harm resulted to the plants and the 

 maggots were destroyed. In 1890, one of Prof. J. B. Smith's correspondents 

 reported good results from the use of the emulsion diluted 15 times. Mr. 

 Fletcher found the emulsion successful in 1892 and 1893 ; but says it is not 

 practicable for field use. The Riley-Hubbard formula* for the emulsion has 

 been used since 18S8. 



The evidence so far is quite conflicting. Evidently the emulsion is the 

 most effective when made by the Riley-Hubbard formula ; but unless each 

 gallon is diluted with at least 12 gallons of water, the plants are injured. 



May 23, we placed 100 small maggots on the base of a well established cab- 

 bage plant. The next day, after they had begun feeding on the root, 4 oz. 

 of the emulsion diluted with 9 parts of water was poured in a cavity about 

 the plant ; and a similar amount of a i to 12 part dilution was similarly ap- 



*To make the Emulsion, thoroughly dissolve one-half pound hard or soft soap in one 

 gallon boiling water. While this solution is still very hot add two gallons of kerosene and 

 quickly begin to agitate the whole mass through a syringe or force-pump, drawing the 

 liquid into the pump and forcing it back into the dish. Continue this for five minutes or 

 until the whole mass assumes a creamy color and consistency which will adhere to the 

 sides of the vessel, and not glide off like oil. It may now be readily diluted with cold rain 

 water, or the whole mass may be allowed to cool when it has a semi-solid form , not unlike 

 joppered milk. This standard emulsion if covered and placed in a cool dark place will 

 keep for a long time. In making a dilution from this cold emulsion, it is necessary to dis- 

 solve the amount required in three or four parts of boiling water, after which cold rain: 

 water may be added in the required quantities. 



