CSLB C-27 Landscaping ContractorPlanting and LandscapingMedium
A landscape technician is applying a systemic insecticide to a client's mature oak tree to control an infestation of aphids and other sucking insects. To ensure the chemical is effectively absorbed and translocated throughout the tree, what is the most important consideration regarding soil moisture at the time of application?
- ASoil moisture is irrelevant as systemic insecticides are primarily foliar absorbed.
- BThe soil should be saturated to ensure rapid absorption by surface roots.
- CThe soil should be completely dry to prevent dilution of the insecticide.
- DThe soil should be moist to facilitate uptake by the tree's root system.
Show answer & explanationAnswer & explanation
Correct answer: D. The soil should be moist to facilitate uptake by the tree's root system.
Systemic insecticides applied to the soil are absorbed by the tree's root system and then translocated throughout the plant. For effective root uptake, the soil must be moist, but not saturated, to allow for proper absorption and movement of the chemical into the vascular system.
Why the other options are wrong
- A. While some systemic insecticides can be foliar applied, the question specifies application to a mature oak tree for control of aphids, implying soil application for systemic uptake, making soil moisture highly relevant.
- B. Saturated soil can lead to anaerobic conditions, harming roots and hindering absorption; it can also cause runoff.
- C. Dry soil inhibits root uptake of systemic insecticides, making the application ineffective.
Systemic Insecticide Soil Application
Applying insecticides to the soil around a plant, where the roots absorb the chemical, which then moves throughout the plant's vascular system, making the entire plant toxic to feeding pests.
- Requires root uptake and translocation.
- Soil must be moist for effective absorption.
- Provides broad, long-lasting protection against sucking and chewing insects.
- Avoids drift and direct applicator exposure associated with foliar sprays.
Memory trick: Systemic Sip: Roots need a drink to send the poison up!