Maria from Portland, Or writes,
The bentgrass is gone. How often do I need to spray Tenacity to keep the bentgrass out?
I don't want the bentgrass to come back. Please let me know at what interval I should spray Tenacity.
We apologize but there is not an exact time frame of how often you should apply the Tenacity Herbicide to keep the bentgrass out of your lawn. The product label states that the Tenacity acts as a pre and post emergent on bentgrass so it should help prevent it for at least a few months if you sprayed recently as a spring application. Post emergent wise, you would apply it as you start to see new signs of bentgrass growth to eliminate it as its come up at that point. Tenacity is a strong product so you dont want to over apply the product and risk harming/burning your lawn or whiten it too much. You could easily apply it every 3 or 4 monts and should be fine however per the product label regarding treating for bentgrass it states:
Control of bentgrass (Agrostis spp.) and nimblewill (Muhlenbergia schreberi) – Apply Tenacity at 5 fl. oz. per acre in at least 30 gallons of water per acre at two to three week interval for up to three applications. Apply with a NIS surfactant. Bentgrass control may be more effective in the late summer/early fall just prior to onset of renewed bentgrass growth, than spring/early summer applications.
Answer last updated on: 02/11/2015