What are systemic pesticides commonly used for?

Systemic pesticides are specifically designed to enter the plant system and provide protection from harmful organisms, such as sap-sucking insects and pathogens. When these pesticides are absorbed by the plant, they circulate through its tissues, making it effective in reaching various parts of the plant, including those that may not be directly sprayed. This mode of action allows systemic pesticides to help prevent infestations and diseases that can significantly impact plant health and productivity.

The other choices refer to different functions or properties that are not the primary use of systemic pesticides. For instance, options about enhancing plant growth or improving soil quality pertain more to fertilizers and soil amendments rather than pest control methods. Repelling pests through odors relates more to certain types of repellents that may not have a systemic action. Therefore, the primary purpose of systemic pesticides is accurately captured in the choice about protecting plants from harmful insects and pathogens.