Post-emergence herbicides are applied after the weeds and the crop emerge. This is because of the selective nature of the herbicides and it is important to avoid drift so that the herbicide does not fall onto an unintended crop
Mankhwala ophera tchire othire mbewu zitamera amathiridwa tchirelo komanso mbewu zitamera. Izi zimachitika chifukwa mankhwalawo amasankha tchire loti aphe ndipo ndikofunika kupewa kuwuluka kwa mankhwala kuti asagwere pa mbewu zomwe sizofunika kuti zife