Herbicides on weeds and crop selectivity

1 -selective herbicide (selective herbicide): these herbicides in a certain dose range, can kill weeds while the crop no poison, or poison is very low. Such as 2,4 - drops, MCPA ,liquid sprayer dicamba , bentazon , oats fear , propanil and stable killing and so on. Relative selectivity of herbicides only in certain doses, the crop growing specific security . Administered overdose or sensitive period of application of the crop will affect crop growth and development , or even kill crops.

(2) non-selective herbicides or herbicide (non-selective herbicide): these herbicides on crops and weeds have toxic effects , such as glyphosate , paraquat ( Gramoxone ) and so on. These herbicides are mainly used in non-cultivated land or kill weeds before crop emergence , or spray with a protective cover crops between the rows in the directed manual sprayer spray .