Crop Production and Management — Science STD 8 — Question

The process of removal of weeds is called weeding. It is necessary to remove weeds time to time because
(i) These unwanted plants are harmful because they competes with the crop plant for the nutrient, fertiliser, space, light and water. Thus, they reduce crop yield.
(ii) Some weeds interfere even in harvesting and may be poisonous for animals and humans.
Weeding Methods
Farmers adopt many ways to remove weeds and control their growth. Tilling before sowing of crops helps in uprooting and killing of weeds which may then dry up and get mixed with soil. The best time for the removal of weeds is before they produce flowers and seeds. Weeding can be done either manually or by spraying weedicides as.
discussed below
Manual Weeding
In this method, the weeds are removed from the crop field by pulling them up by hands and throwing them away. Another method of manual weeding is done by using a khurpi. A seed drill is also used to uproot weeds.
Spraying Weedicides
Certain chemicals called weedicides (herbicides) like 2,4-D are sprayed in the fields to kill the weeds. The crops remain unaffected from weedcides.
It should be sprayed during the vegetative growth of weeds before flowering and seed formation, otherwise weeds become difficult to control. Precautionary measures such as covering nose and mouth with cloth should be taken while spraying weedicides, as they impose health hazards.