60 CHAPTER IV 



the early winter and leaving the soil in such a condition that 

 it will dry out thoroughly, the rhizomes then being destroyed 

 by frost and by desiccation. In those parts having a winter 

 rainfall the ground should be ploughed in spring. These weeds 

 will then be killed by desiccation during the hot, dry summer. 

 On sandy soils ploughing at the times stated will have to be 

 followed by frequent haiTowings in order to keep the rhizomes 

 exposed. 



General Methods of Weed Control. — (1) Prevent as 

 far as possible the production and introduction of weed seeds. 



(2) Practise a rotation of crops — annuals can be destroyed 

 to a great extent during the growth of the cultivated crops, 

 and perennials by the various ploughing and harrowing opera- 

 tions. 



(3) Delay planting, if necessary, in order to harrow fre- 

 quently as the weed seedlings appear. Harrow most crops 

 until just before they are appreciably injured. 



(4) If the land is very weedy it may be necessary to bare 

 fallow. 



(5) Ploughing as soon as the crop is removed will prevent 

 seed production to a considerable extent. 



(6) Smothering crops such as Buckwheat and Cowpeas 

 will be found useful. 



(7) Some weeds are readily eaten by stock, in which case 

 heavy stocking will be of assistance. 



(8) Frequent mowing is often helpful in weakening the 

 plants and in preventing the production of seeds. 



(9 In some cases hand-pulling and hoeing, followed by 

 burning, is necessary. 



(10) Spraying is resorted to where farming is very inten- 

 sive. Effective solutions are : 12 pounds of copper sulphate, 

 or 100 pounds of iron sulphate, or 125 pounds of common salt 

 to 50 gallons of water. 



Below are given some practical details in regard to the 

 control of a few common and very troublesome weeds : 



Dodder (Cuscuta trifolii). — This weed is parasitic on 

 lucerne. The seed germinates in the soil, but the plant subse- 

 quently becomes wholly dependent on its host for existence. 

 The plants should not be removed. Dry brush or grass should 

 be piled on infested spots and then burned. Care must be 

 taken to watch for subsequent infestations. If fields are badly 

 infested it is necessary to plough under the whole crop, and for 

 several seasons following to plant crops like notatoes or wheat. 

 Dealers selling lucerne seed containing Dodder seeds are liable 

 to be prosecuted. 



