11 



no more effect would be thus obtained, and the risk would be run 

 of introducing too much arsenic into the soil. 



At Ulupalakua some losses have been experienced in the 

 death of cattle from eating a poisonous passion vine which has 

 gradually spread over a small area of the ranch land. The arse- 

 nite of soda is now being used for destruction of this plant and 

 also to kill the air plant (Bryophyllum calycinum), a useless 

 weed which covers some of the range and prevents other plants 

 from growing. It is commonly considered that red sage (Salvia 

 coccinea) causes abortion in cows and mares. The evidence for 

 this belief is quite conclusive and has come from a number of 

 ranches. The arsenite of soda is now being used on Lanai for 

 the destruction of this weed. 



The chemical method for the destruction of weeds as de- 

 scribed in this bulletin is capable of a much wider application, 

 particularly for killing weeds along roadways and in waste 

 places where cultivation is at present out of the question. It 

 should, of course, be remembered that the arsenite is poisonous 

 and stock animals should not be allowed to browse upon 

 sj)rayed vegetation until after sufficient rain has fallen to wash 

 off what may remain on the foliage. As a rule the effect of the 

 spray begins to be manifested within a few hours in the wither- 

 ing and browning in the leaves of sprayed plants. They are 

 thus rendered unpalatable as feed for animals. The spray must 

 remain in contact with the foliage for at least two hours, in 

 order to have the desired effect. In applying arsenite, therefore, 

 a clear day should be chosen, or at least one in which it is not 

 likely to rain soon after the application of the pray. 



POSSIBLE DANGER FROM THE USE OF 

 ARSENITE OF SODA. 



In addition to the danger of stock becoming poisoned from 

 grazing on sprayed vegetation, it seems desirable to consider the 

 possible injurious effect of arsenic upon the soil and cultivated 

 crops which may be growing in the soil at the time, or which may 



