3i 



thousand was required to kill the plants. Could a current be inade 

 to pass through the plant from the tip of the root to the tip of the 

 stem a much smaller voltage could be used. 1 have killed small 

 plants in the laboratory with an electrical force equal to forty or 

 fifty volts when the current was applied in this manner. Even 

 supposing such appliances could be devised on a simple and cheap 

 scale, so as to be utilized, they would be of no value when applied 

 to cultivated crops, inasmuch as one of the blessings of weeds is 

 that they remind the gardener that it is time for his crops to be 

 hoed, and any appliance which fails to stir up the soil would be an 

 injury rather than a help- 

 Other methods have been tried for weed eradication with more 

 success. The application of chemicals to freshly cut roots, or at 

 the base of the stem, has been used in some instances with success. 

 For this purpose experimenters have resorted to the use of coal 

 oil, crude sulphuric acid, salt, strong brine and carbolic acid. A 

 few drops of carbolic acid applied with an ordinary machine oil 

 can is considered the best method that has devised for killing weeds 

 with chemicals. Salt has been used with some success on the 

 Canada thistle and golden hawkweed. Experiments upon the 

 golden hawkweed in Vermont with salt at the rate of three thou- 

 sand pounds per acre have proven effectual, and at the same time 

 have increased the yield of grass. 



In the case of biennials, cutting the root below the crown usually 

 kills them ; but occasional mowings induce them to send up numer- 

 ous stalks from their roots, which, if not cut, will come to matu- 

 rity and produce seed. The wild carrot affords an example of a 

 biennial, and outside of hand pulling repeated mowing is about 

 the only practical method which can be employed. This prevents 

 the plant from maturing its seed, and also by checking assimilation 

 starves the plant out. 



Many root-stalks are successfully killed by exposing them to the 

 direct action of the sun in summer or of frost in winter. Plough- 

 ing in this manner becomes effective. Certain root-stalks possess 

 a remarkable power for propagating themselves, and when cut up 

 even in small pieces they are capable of growing into a new plant. 

 Any cultivation, therefore, which only breaks the root-stalks and 

 leaves them in the ground during warm, moist weather is not prac- 

 tical, as this method would only multiply them. 



One of the best methods for destroying the very troublesome 

 couch-grass is to plough it up late in the fall and sow the piece 

 down thickly with some such crop as rye. 



In fact, this is one of the best methods to which farmers can 

 resort to for weeds in general proper to cultivated lands. Instead 



