Question: what are the three main types of use for herbicides?
Answer: Herbicide Types. Herbicides can be classified in several ways: effect, selectivity, persistence, application and action. ... 
Effect. Pre-emergent herbicides: Work as they interfere with seed germination. ... 
Selectivity. ... 
Persistence. ... 
Application. ... 
Action. ... 
Glyphosate Herbicide. ... 
References.