What kind of herbicide should be avoided near the roots of non-target trees?

The correct answer involves recognizing the characteristics of soil-residual herbicides and their potential impact on non-target vegetation, particularly trees. Soil-residual herbicides are designed to remain active in the soil for extended periods to control emerging weeds. When these herbicides are applied near the roots of non-target trees, there is a risk that the chemical may be taken up by the tree's root system, leading to harmful effects on the tree's health or growth.

In contrast, selective herbicides target specific types of plants while minimizing harm to others. Contact herbicides act on contact and do not typically leave residual activity in the soil. Systemic herbicides are absorbed and translocated throughout the plant but are usually designed for specific control of certain vegetation. Therefore, while there may be caution needed with all types of herbicides, soil-residual herbicides pose the greatest risk to non-target trees due to their persistence and potential for root uptake. This underscores the importance of understanding herbicide behavior in the environment, especially when managing pest populations in proximity to sensitive species.