Soil-applied pesticides are applied to the soil; some are taken up by roots and translocated inside the plant. Others kill weak seedlings by contact with young shoots or leaves as they break through the soil. Which of the following best describes this application method?

• A. They are applied to the leaves
• B. They are applied to the soil; some are taken up by roots and translocated inside the plant.
• C. They are applied to seeds
• D. They are sprayed in the air

Answer: (B)

Soil-applied pesticides can do two things: some are taken up by plant roots and moved within the plant (systemic action), while others act by contact on the parts that appear as the plant emerges, killing weak seedlings as they break through the soil. The statement that describes applying the chemical to the soil and notes that some are taken up by roots and translocated inside the plant, while others kill weak seedlings by contact with young shoots or leaves as they emerge, captures both these fates. This is different from applying pesticides to the leaves (foliar sprays), to seeds (seed treatments), or spraying them into the air (fumigation or aerial applications). Therefore, this soil-applied description best fits the method.