Unfortunately, it is not uncommon for weeds to emerge shortly post-installation. Areas that receive new topsoil, have been cultivated, and will be receiving heavy irrigation for new sod establishment are prone to weed growth where weeds may not have been growing in the past. Additionally, seeds may be windblown, spread by birds, or introduced when adding new topsoil. Soil is stored outside, so even when you purchase new soil, it is often contaminated with weed seeds. Further, weed seeds can lay dormant in the soil for years, germinating once the soil is worked and the seeds are exposed to the sun & increased moisture.
All of our turfgrass farms are on a regular maintenance schedule, including preventative pre-emergent & post-emergent herbicide applications. However, sometimes excessive or long rain periods can delay our regular schedule. As soon as the fields dry out, we reenter the fields & apply the pre-emergent. We also selectively spray any weeds with post-emergent herbicides asap if any are scouted during QC inspections. Typically, any weeds that have the opportunity to sprout or survive the first herbicide application will begin to wilt and die back within a couple of weeks post-application/delivery.
Because weeds can spread so many ways, it can be challenging to know with 100% accuracy where the weed seeds originated, especially the more time that passes from the day of delivery. The image to the left is an example of weeds originating from the soil. You can see that the weeds are predominately popping up through the seams between the blocks of installed grass & not throughout the grass, indicating that the weed seeds were in the existing earth or introduced with the new topsoil. Another way to check is to lift the block of sod to see were the root is coming from.
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- Improper Ground Prep
- Unscreened/Poorly Screened Topsoil
- Drought-Stressed Grass
- Over-Irrigation (select weeds, such as nutsedge)
- Unhealthy Sod
- Incorrect/Lack of Maintenance
- Contamination (birds, shoes/clothing, neighboring yard/field, wind, improper weed removal, etc.)
- Hand-Pull (select weeds)
- Weed Identification
- Select & Apply Appropriate Herbicide
- Follow-up Application (as needed)
- Seasonal Pre-emergent Herbicide
- Correct Maintenance Schedule (proper irrigation, pre-emergents, fertilization, etc.)