1. The critical period of weed competition is the shortest time span during the crop growth when weeding results in highest economic returns.
2. The crop yield level obtained by weeding during this period is almost similar to that obtained by the full seasons weed free conditions.
3. The critical period of weed competition is also defined as the period between early growth during which weeds can grow without affecting crop yield and the point after which weed growth does not affect the yield.
4. The critical period of weed competition is approximately 1/3rd of the duration of the crop.

Rice (Transplanted) Upland Rice Wheat Maize Sorghum Finger Millet Soybean Blackgram Cotton Sugarcane Groundnut Sunflower Castor Sesame

15 Entire period 30 15 15 25 15 30 15 30 30 30 30 15

45

45 45 45 45 45 45 60 120 50 45 60 45