In Tamil Nadu, tomatoes are being grown in three seasons namely June-July, December January and March.

The critical period of weed competition in tomato is the first 30 days after transplanting. For the control of annual grasses, pre-planting soil incorporation of Trifluralin 3 to 5 kg/ha or Nitralin 3 to 5 kg/ha or Diphenamid 2 to 4 kg/ha is best.

Similar application of EPTC 2 to 3 kg/ha controls nut grass. Effective pre-emergence herbicides of Pendimethalin 1.00 kg/ha, Alachlor 1 to 2 kg/ha, Metribuzin 0.75 kg/ha, Fluchloralin 1.0 kg/ha followed by one hand weeding on 30 DAS. Generally, a pre emergence herbicide followed by one hand weeding in the later period of crop growth gives complete weed control.

Herbicides which need pre-plant incorporation are particularly useful in the nursery.

In the transplanted field they are applied 3 to 4 weeks before planting seedlings.