REMEDIAL MEASURES. 61 



was due to eating the poison or to the effect of fumes has not been 

 determined. 



The results in the use of strychnine and potassium cyanid have 

 been quite well verified in an entirely independent series of experi- 

 ments carried on by Mr. R. S. Vaile. 



From the foregoing it can be seen that the experiments thus far 

 tried in the use of poisoned bait against the sugar-beet wireworm 

 have been far from satisfactory. Thej^ are to be continued in future 

 work. 



EXPERIMENTS WITH GUANO FERTILIZER. 



The only fertiUzer tested on the wireworms was a mixture of bird 

 and bat guano, a South American product, whicJi is chiefly nitroge- 

 nous and is characterized by a strong and lasting odor of ammonia. 

 It was lioped that the strong ammonia odor would drive tlie wire- 

 worms deeper into the soil. The results from its use thus far — ^it 

 has been tried only on a small scale in the laboratory — seem to indi- 

 cate that it would have to be used at the rate of from 8 to 10 tons 

 per acre to be partially effective. As this is many times heavier 

 than an average dressing for the soil it would probably be impractical 

 to use it. 



PROTECTION OF BEETS BY EARLY PLANTING. 



The protection of beets by early planting is a remedy wliich was 

 early suggested by Mr. H. M. Russell and has since been given a 

 practical test on a large scale. The advantage of tliis method is 

 very plain. When the beets are planted early the plants are quite 

 hardy and the roots are swollen by the time the wireworms are doing 

 their worst injury. (See PL XIX, fig. 1.) These swollen roots can 

 stand a severe attack without having their sap supply cut off, and in 

 consequence a much smaller number of them are killed. 



Mr. H. J. Mayo, one who grows sugar beets on a large scale in both 

 Los Angeles and Orange Counties, writes as follows concerning early 

 planting: 



* * * In the season of 1911 I planted early and the results were very good, 

 especially on the heavy land, as the beets seemed to get a start, and the worms did not 

 seem to affect them so much, although they were in the ground and from examinations 

 that, I made they worked on the beets; but where the beets got the start the worms 

 did not bother them so much. 



In my opinion early planting will relieve a great deal of the danger of the wireworm. 



Clean Cultltre against the Adui.ts. 



The foUo-wdng in regard to remedial measures is the result neither 

 of theory nor of experiment. It was suggested to the writer by 

 observations taken in the field at the time the liibernating beetles 



