Hawaii Agricultural Experiment Station, 



HONOLULU. 



E. V. WILCOX, Special Agent in Charge 



PRESS BULLETIN NO. 25 



Carbon Bisulphid for Killing Weeds 



By E. Y. WILCOX, 

 Special Agent in Charge, Hawaii Agricultural Experiment 

 Station, United States Department of Agriculture. 



In the perpetual conflict with weeds it becomes necessary 

 to make use of every weapon which shows efficiency in destroy- 

 ing them. The conditions under which different crops are 

 raised indicate different methods as best adapted to the vari- 

 ous conditions of each case. During the past year a number 

 of experiments have been made with carbon bisulphid in 

 studying its effects upon various herbaceous and shrubby 

 weeds. In these experiments, the amount of carbon bisulphid 

 used varied according to the size of the plant to be destroyed. 

 On small-stemmed plants like C rot aJ aria, about a teaspoonful 

 of commercial bisulphid was poured down the stem, from about 

 six inches above the ground. The amount was increased, for 

 larger plants, up to two tablespoonfuls for guava bushes three 

 or four inches in diameter. The plants upon which most of 

 the tests were made were lantana, guava, prickly-pear, Stacliy- 

 tarpheta dicotoma (one of the plants known by the native name 

 Oi), and Crotalaria incana. In all cases, as just indicated, the 

 carbon bisulphid was poured on the stem at a point about six 

 inches above the surface of the ground. On most plants carbon 

 bisulphid shows no eft'ect until after the lapse of a considerable 



