Major Weeds
Amaranthus viridis	Boerhaavia diffusa	Celosia argentena
Chloris barbata	Cynodon dactylon	Cyperus rotundus
Portulaca oleracea	Trianthema portulacastrum

The wide row spacing and initial slow growing nature of the crop is ideal for weed growth. Critical period of weed competition is first 20 to 60 days after seeding.

In rainfed castor crop, two or three intercultivations with bullock drawn blade harrows, starting from 20 DAS along with a manual weeding with in the row can effectively check the weed growth. Square planting is adopted in certain areas of Andhra Pradesh to run the blade in both the directions for effective weed control.
           
In irrigated castor, 2 to 3 hand weedings at an interval of 15 days, starting 15 DAS can check the weed growth effectively. Alternately, herbicides may be used against the weeds.

Use of Herbicides: Several herbicides are available for weed control in castor. Use of herbicides may be economical in irrigated castor. Any of the following herbicides are effective in castor crop.

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Image Source:
-- www.agritech.tnau.ac.in
-- Dr.R.Jagannathan,
   Professor of Agronomy,
   TNAU, Coimbatore-3.