Which herbicide works strictly by contact and desiccates treated plants but they will regrow from the crown?

Which herbicide works strictly by contact and desiccates treated plants but they will regrow from the crown?

• A. Diquat
• B. Monument
• C. SedgeHammer
• D. Finale

Answer: (A)

Understanding how a herbicide moves and acts inside a plant helps predict what happens after application. A true contact desiccant does its work only where it touches the plant, drying out the treated tissue, and it doesn’t move much within the plant. If the crown or root isn’t destroyed, the plant can regrow from those structures. Diquat fits this pattern exactly. It acts on contact to desiccate the tissues it touches, with little internal movement, so untreated parts of the plant can survive. That’s why you see desiccation on the treated sections while the crown can send out new growth later. The other products don’t match this strictly contact-desiccant behavior: they either move within the plant (systemic action) or have soil/residual effects, so they don’t kill only what they touch and then allow regrowth from the crown in the same way.

Understanding how a herbicide moves and acts inside a plant helps predict what happens after application. A true contact desiccant does its work only where it touches the plant, drying out the treated tissue, and it doesn’t move much within the plant. If the crown or root isn’t destroyed, the plant can regrow from those structures.

Diquat fits this pattern exactly. It acts on contact to desiccate the tissues it touches, with little internal movement, so untreated parts of the plant can survive. That’s why you see desiccation on the treated sections while the crown can send out new growth later. The other products don’t match this strictly contact-desiccant behavior: they either move within the plant (systemic action) or have soil/residual effects, so they don’t kill only what they touch and then allow regrowth from the crown in the same way.