VERMONT AGRICULTURAL, REPORT. 15 



or woody plants. Of course, soil so treated will be rendered 

 sterile for some time, but the soda will gradually leach away. 

 Like salt, tliis is most effective if applied in hot, dry weather. 



Arsenical compounds. One or another of the soluble arsen- 

 ical compounds form the most effective herbicides known. These 

 form the basis of all of the various proprietary "herbicides" 

 or "weed killers" that we have analyzed. Such compounds are 

 handled by leading horticultural supply houses, and, so far as 

 we have tested them, are highly efficient. The only reason for 

 seeking elsewhere is their high price. Soluble arsenical poisons 

 can, as a rule, be bought considerably cheaper in the drug trade 

 and are similar in action. The simplest to employ is Arseniate of 

 Soda. This needs only to be dissolved in water for use (at rate 

 of I pound dissolved in 3 to 9 gallons of water). White arsenic 

 is still cheaper, but according to Schutt's formula, which we have 

 used, it must be combined with sal soda, which is somewhat of 

 a bother. (White arsenic, i pound ; washing soda, 2 pounds ; 

 water, 3 to 9 gallons). An important characteristic of these 

 arsenical poisons is that they endure for a long time and do not 

 readily wash or leach away. For this reason they are the most 

 useful herbicides to use on roadways, etc., as explained below. 



more: specific directions eor use. 



Any of the above chemicals will kill any plant if applied 

 directly to it in sufficient amount. In addition to the more gen- 

 eral advice included in the above account, the following specific 

 directions are adapted to special cases. 



Gravel roadways, gutters, tennis courts, etc., can be kept 

 free from weedy growths by application of any of the above. 

 If salt is used it should be scattered freely in the dry form. Cau- 

 tion is necessary where it is liable to be washed on to lawns, lest 

 it damage the grass borders. Carbolic acid or arsenical poisons 

 are preferable, both as less liable to wash and as more enduring 

 in their action. One quart of crude carbolic acid in 8 gallons 

 of water, or one pound of either arsenical compound mentioned 

 above, in a like amount of water will suffice to cover a square 

 rod or more of surface, and one, or, at most, two applications 

 per year suffice. 



Charlock, known also as kale or wild mustard (Brassica 

 Sinapistrum) is easily destroyed in oat, wheat, or other grain 

 fields, by spraying with a solution of i pound of copper sulphate 

 in 4 to 6 gallons of water (2 to 3 percent solution). A force 

 pump should be used, supplied with fine nozzles. The treatment 

 is most effectively made when the grain is 3 to 6 inches tall, 

 since at this stage the large charlock leaves spreading abQve th& 



