Why is the type of weed important?

Being able to identify the weeds is important, as it helps determine the expected level of the problem as weeds vary in the extent to which they can reduce yield and or quality.

• Tells extent of potential yield loss e.g., weedy rice 70% loss, Sesbania 19% loss
• The type of weed can also tell you about the field and its management. For example, the presence of
  • Lpomoea aquatica indicates prolonged water logging
  • Cyperus difformis indicates water has not been limiting
• Tells best method of control

The type of weed also tells about the best form of direct control. For example, if a weed spreads by vegetative propagation then plowing and other similar practices will simply spread the problem. Also agrochemicals are often weed specific. So you need to know the type of weed to select the right product.