How can pesticides injure nontarget plants?

Pesticides can injure nontarget plants primarily by moving into the root zone. This movement can occur through various pathways such as leaching or runoff, where the active ingredients of the pesticide travel through the soil and affect a plant's root system. When the roots of nontarget plants come into contact with these chemicals, it can disrupt their normal physiological processes, leading to symptoms such as stunted growth, leaf burn, or even plant death.

The correct understanding of how pesticide mobility impacts plants is crucial, as it highlights the importance of proper application techniques and consideration of environmental factors. In contrast, other choices do not accurately reflect how nontarget plants can be harmed. For instance, merely affecting the leaf surface does not account for the broader potential for damage that can occur below ground level. Enhancing growth or increasing chlorophyll production would have a positive effect and are not mechanisms through which pesticides cause injury.