CiKcn.AR NO. 11. 



United States Department of Agriculture, 



DIVISION OF BOTANY. 



THE VITALITY OF SEED TREATED WITH CARBON BISULPHID. 



INTRODUCTION. 



The ravages of weevils and other insects in seed grain are well 

 known to every farmer, and are the cause of very serious loss in the 

 value of the seed both for sowing and food purposes. In some of 

 the Southern States, especially, are such ravages so severe that it is 

 often difficult to get sound seed for sowing. The cowpea, corn, 

 wheat, rice, and garden and field peas are the main subjects of attack, 

 but even vegetable seeds are not exempt. 



Seeds of the common pea are frequently badly infested with wee- 

 vils even when grown as far north as Canada. Some seedsmen claim 

 that such insects never injure the embryo, hence do not lessen the 

 sowing value of the seed. This, however, is a serious error; for not 

 only is the embryo frequently injured, sometimes even destroyed, 

 but a large amount of reserve material is consumed, the loss of which 

 greatly weakens the vitality of the young seedlings. 



The common remedy advised by entomologists for destroying seed- 

 infesting insects is to treat the seed for twenty-four hours with the 

 fumes of carbon bisulphid at the rate of one pound to the hundred 

 bushels. This chemical when pure is a colorless liquid with a pleas- 

 ant odor. Upon exposure to the air the carbon and sulphur com- 

 posing the liquid are separated, each uniting with oxygen, for which 

 they have a stronger affinity than for each other. Thus are formed 

 carbon oxid and sulphur dioxid, the latter being a very poisonous gas 

 with a disagreeable odor. 



The statement is made that seed grain may be exposed to these 

 fumes for thirty-six hours without injuring its germinating capacity. 

 So far as we are aware no extended experiments have heretofore 

 been made to test the truth of this statement which, however, is gen- 

 erally accepted and which has very important bearings. For if the 

 treatment recommended is detrimental to the germinating power of 

 the seed, one by adopting it not only would lose his seed, but what 

 is far more serious, would be subjected to delay in waiting for it to 

 come up and then be under the necessity of resowing. 



