DESTRUCTION OF FLY LARVAE IN HORSE MANURE, 1915. 17 



In connection with the use of cyanamid as a fertilizer, the following 

 statements of E. J. Pranke (6) are of interest: 



Since cyanamid is a medium slow-acting fertilizer, it should be applied to the crop 

 not less than 70 to 80 days before the harvest, in order that the nitrogen may be com- 

 pletely utilized by that crop. Experience has shown that the most economical 

 utilization of a nitrogen fertilizer is in conjunction with the other fertilizer elements, 

 phosphorus and potash. For this reason it is recommended that cyanamid be used 

 as a part of a fertilizer mixture rather than it be applied alone. 



If cyanamid is to be applied to very acid soils, such soils should be put in a produc- 

 tive condition by judicious liming sometime before the application of the fertilizer. 

 The application of barnyard manure will help to establish the bacteria that are deficient 

 in such soils. 



EXPERIMENTS WITH BORIC ACID AND SULPHUR. 



Boric Acid, B(OH) 3 . 



Two open-pile experiments were carried out, using solutions of 

 boric acid, one-fourth pound to 5 gallons of water, and applying the 

 same to 4 bushels of manure. The tests showed a 97.4 per cent and 

 a 99.8 per cent larvicidal action. Boric acid was quoted wholesale 

 January 1, 1916, at 10 to 10 \ cents per pound for commercial grade. 

 Based on the price just quoted, the cost of treating manure with 

 boric acid, judging from these two tests, was five-eighths cent per 

 bushel of manure. It is probable that somewhat smaller amounts of 

 boric acid than one-half pound per 10 gallons of water may be effect- 

 ively employed. Borax cost, January 1, 1916, from 5J to 6 cents per 

 pound wholesale, or 4 cents for two-thirds of a pound, a quantity 

 sufficient to destroy all the maggots in 8 bushels of manure. The 

 cost was therefore one-half cent per bushel of manure. It is apparent 

 that boric acid is equally effective as borax as a larvicide, but it has 

 not been determined whether there is any difference in the action 

 of these two substances on plant growth, although from the few tests 

 reported in the literature no differences are indicated. 



Sulphur. 



One box test in which one-third of a bushel of manure and 5 J ounces 

 of flowers of sulphur were used was carried out at the suggestion of 

 Prof. C. V. Piper. A control was employed, both samples being mois- 

 tened and a large number of fly eggs added to each. Forty- two flies 

 emerged from the box treated with sulphur and 909 flies from the 

 control. The application of 1 pound of sulphur per bushel of manure 

 is a large one, and, if used on a large scale, would not only involve 

 considerable expense, but would undoubtedly have an injurious action 

 on plants when applied to the soil. 



SUMMARY. 



During the fly season of 1915, the larvicidal action of infusions of 

 18 plant materials was tested. None of these, with the exception of 

 hellebore, were sufficiently economical and effective to be classed as 



