REMEDIAL MEASURES. 59 



THE USE OF POTASSIUM CYANID AGAINST THE WIREWORMS. 



Potassium cyaiiid was one of the first remedies tested for the wire- 

 worms, because it has the properties both of an excellent deterrent 

 and a deadly poison. Used as a deterrent, the seeds were treated in 

 two different ways. In the first the cyanid was used as a solid and 

 drilled in with the seed. This method affords excellent protection 

 to the seed, but the drawbacks connected with it have thus far made 

 it unpracticable. The cyanid burns the seed wherever it comes in 

 contact with it, and when germination begms, it burns the tender 

 roots. Another argument against its use for this crop is its cost. In 

 the second method of seed protection the seeds were soaked over- 

 night in a solution of cyanid in water, dried, and planted. In this 

 method it was also quite effective as a deterrent, but unfortunately 

 its effects on the roots were such that it could not be used. At the 

 present time it seems very doubtful if the cyanid can be used in such 

 a strength that it will keep away the wireworms and at the same 

 time not harm the plants. This point is going to be tested further. 



\^'Tiile these experiments were being carried on it was noted that 

 in some of the cages most or aU of the wireworms had been killed. 

 These larvae had the appearance of having been killed by a fungus, 

 but as then* bodies were not filled with the fungus it was apparent 

 that they had been killed in some other way. It was thought that 

 perhaps they had been killed by the fumes of the cyanid, and later 

 experiments seemed to bear out this point. With this in view, many 

 experiments were carried on in an attempt to discover some good 

 method for the application of the cyanid. From these, two plans 

 were selected for final trials, one in which the cyanid was used as a 

 solid, and the other in which it was used as a liquid. The results are 

 given below. 



According to the fu'st plan the cyanid was drilled into the ground 

 much after the method used for fertiUzers. This plan was finally 

 given up, as the cyanid was not distributed evenly thi'ough the soil, 

 and therefore had to be applied more heavily than was necessary in 

 order to be effective. As the cyanid is very destructive to plant 

 growth it is readily seen that it would have to be used as sparingly 

 as possible. 



The metliod of using the liquid consisted in making a solution of 

 the cyanid in water and applying it evenly over the land. This 

 could then be made to permeate the soil to any depth by irrigation. 

 By this method the cyanid is used sparingly, as it is evenly applied. 

 Unfortunately it has been impossible to try this remedy thoroughly, 

 up to the present time. In all the experiments where this method 

 was employed its killing power was very good. To test it further, 

 it was applied in a cage containing beets, with the result that both 



