What types of organisms does systemic treatment aim to control?

Systemic treatment is designed to control specific types of pests that can significantly affect plants, particularly certain kinds of fungi and insects. This method involves the uptake of a treatment through a plant's vascular system, allowing it to distribute the active ingredients throughout the plant's tissues.

Fungi, particularly plant pathogens such as rusts, blights, and root rots, can lead to serious diseases that affect the health and yield of plants. By employing systemic treatments, the plant can bolster its defenses against these fungal infections.

Insects, especially sap-sucking pests like aphids and whiteflies, are also targets for systemic treatments. The chemicals involved are absorbed by the plant and can deter or kill these pests when they feed on the plant, reducing damage and the spread of possible diseases they might carry.

This method is advantageous as it provides long-lasting protection by introducing the active ingredients into the entire plant system, rather than just applying them to the surface, which is often less effective against pests that are not exposed to the treatment directly.

The other options do not accurately reflect the primary focus of systemic treatments, as they do not account for the range of diseases and pests that are effectively managed through this approach.