Question

Should farmer use the same herbicide year after year?

Answer 1

yes there is no problem on that

Answer 2

If the same of weeds are found in the farm, then farmer should not use same type of herbicide to control weed.

This happens because of resistance of herbicides in those weed species. It won’t able to kill them even at elevated rates.

By the use of same herbicide after year can kill the susceptible plant while the resistant ones survive and spread their population.