How do contact pesticides differ from systemic pesticides?

Contact pesticides and systemic pesticides serve different purposes and function based on their mode of action. Contact pesticides are designed to kill pests upon direct exposure, meaning that their effectiveness relies on the pesticide coming into direct contact with the target organism, such as insects or weeds. When the pest is sprayed or applications occur on the foliage or surface where the pest is present, the pesticide acts immediately to eliminate it.

On the other hand, systemic pesticides are absorbed by plants when applied to the soil or foliage. Once absorbed, these pesticides circulate through the plant's vascular system and can target pests that feed on the plant from within. This characteristic allows systemic pesticides to be effective even if the pest is not directly exposed to the pesticide at the time of application.

The other options highlight aspects that do not accurately distinguish between the two types of pesticides. Understanding the characteristics of contact versus systemic pesticides is crucial for effective pest management and proper pesticide usage in forestry practices.