A1 Field Crops Pest Management Practice Test

Systemic herbicides are designed to be absorbed by the plant, often through the leaves, stems, or roots, and then transported throughout the plant's system. This method is effective because it allows the herbicide to reach all parts of the plant, including roots, which can lead to complete destruction of the plant. This systemic action differentiates these herbicides from contact herbicides, which only damage the parts of the plants they come into direct contact with.

When evaluating the other statements, it's clear they don't reflect the primary mechanism of action for systemic herbicides. For instance, systemic herbicides do not solely rely on uprooted plants to be effective, nor do they work by contact alone—they must be absorbed and circulated within the plant to achieve their intended effect. Additionally, while systemic herbicides may not be effective on all plant types due to variations in absorption or metabolism, the key characteristic that defines them is their mode of transport within the plant, making the statement about absorption and transportation accurate and fundamental to their function.