70 PROTECTION OF PLANTS, 1917-18 



THE USE OF CHEMICAL SPRAYS FOR COMBATTING WEEDS. 



By J. Adams, M. A., Botanical Div., C.E.F., Ottawa. 



That the problem of weeds is a burning question in the Province of Quebec 

 as it is in most other parts of Canada will admit of no doubt whatever. A recent 

 correspondent in a letter dated Uth August, 1916, writes as follows: — "This 

 summer at Franklin Centre, Quebec, I employed part of my vacation exploring 

 the plant life of the district and was much interested in the number of weeds 

 found there. I found forty different varieties along the road side in a distance of 

 not more than a quarter of a mile, not counting small chickweeds, etc.; I found 

 there a G6atsbeard which I had not seen anywhere else in Canada. It seemed to 

 be causing a good deal of annoyance to several of the farmers." 



While it is probable that the hoe and the cultivator will always remain as the 

 principal weapons to employ in the fight with weed?, still any other aids that may 

 help to make the fight more favorable for the farmer are always to be welcomed. 

 One of these auxiliary forces is to be found in chemical methods. So long as ex- 

 travagant claims are not made for them and so long as they are used in their 

 proper place chemical sprays are likely to play a useful part in farm economy. 



It may happen that a grain crop is badly infested with some weed where the 

 only alternatives are hand-pulling of the weed or allowing it to go to seed. Hand- 

 pulling is in most cases quite impracticable owing to scarcity of labor; if, how- 

 ever, the weed can be so damaged (although not killed) by the use of some spray 

 that the formation of seeds is prevented and the grain plants are given more 

 space to mature, the gain to the farmer is very considerable. 



On land that has been allowed to become very foul with weeds it may in some 

 cases be desirable to apply some strong chemical that will destroy all kinds of 

 vegetation at the same time. If this is done early in the season it may be quite 

 possible to destroy the weed and yet secure a fair return from some of the later- 

 sown crops such as corn or turnips. 



There are also numerous plots of waste ground in towns, miles of roadsides 

 all over the country, railroad tracks, and large areas of stony or rocky ground that 

 cannot be cultivated, where the employment of chemical means for keeping down 

 weeds might be profitably considered. 



With the exception of some work on dandelions and wild mustard, very 

 little seems to have been attempted in Canada in the matter of experiments to 

 control weeds by chemical solutions. Some few results obtained in the year 1916 

 at Ottawa are given below; time did not permit the continuation of these experi- 

 ments in 1917. 



