CSLB C-27 Landscaping ContractorPlanting and LandscapingMedium
A landscape technician is applying a granular pre-emergent herbicide to a lawn to prevent annual weed germination. To ensure effective control and minimize off-target movement, what is the most critical factor to consider immediately after application?
- AMowing the lawn to incorporate the herbicide into the soil.
- BAerating the lawn to improve herbicide penetration.
- CApplying a second layer of herbicide for increased efficacy.
- DApplying a deep, slow irrigation to activate the herbicide.
Show answer & explanationAnswer & explanation
Correct answer: D. Applying a deep, slow irrigation to activate the herbicide.
Granular pre-emergent herbicides require water (from irrigation or rainfall) to dissolve and move into the soil profile where they form a barrier to prevent weed seed germination. Without activation, they remain on the surface and are ineffective.
Why the other options are wrong
- A. Mowing immediately after application can disturb the herbicide layer and reduce its effectiveness.
- B. Aeration before application can be beneficial, but immediately after, it can disrupt the herbicide barrier.
- C. Applying a second layer immediately is usually unnecessary and can lead to over-application, potentially harming the turf or causing runoff.
Pre-Emergent Herbicide Activation
The process of watering granular pre-emergent herbicides into the soil to create a chemical barrier that prevents weed seeds from germinating.
- Requires water (rain or irrigation) to be effective.
- Forms a barrier in the top layer of soil.
- Must be applied before weed seeds germinate.
- Prevents a wide range of annual grassy and broadleaf weeds.
Memory trick: Pre-Emergents need a Drink to Do their Job!