Which growth regulators are known for providing residual weed control?

The correct choice is associated with growth regulators that are recognized for their ability to provide residual control of weeds. Tordon, Garlon, and Pathfinder II are examples of growth regulators that contain chemicals that can persist in the soil and continue to inhibit weed growth over an extended period after application.

Tordon, which contains picloram, is effective against a broad spectrum of woody and herbaceous weeds and offers long-lasting control due to its residual activity. Garlon, which primarily contains triclopyr, is particularly effective against woody plants and has similar residual properties. Pathfinder II, being a formulation that combines triclopyr with an oil carrier, also maintains a level of residual activity that helps in mitigating the resurgence of targeted plants.

These characteristics make this group of growth regulators effective tools for managing persistent weed problems in various environments, especially in right-of-way settings where maintaining clear and manageable sites is essential.

In contrast, other choices include growth regulators that may be effective in controlling weeds but do not have the same level of residual activity, making them less suitable for situations where long-term weed control is required.