Quick answer: Phragmites is controlled with a late summer or fall treatment repeated over two to three seasons, followed by replanting. Because it usually grows in or beside wetlands, most projects in New York need state or local approval before any cutting or herbicide work.
What is phragmites?
Phragmites, or common reed, is a tall invasive grass with feathery tan seed heads. It can top 12 feet and forms stands so dense that little else grows. It spreads mainly through underground rhizomes and runners, which is why a small patch becomes a wall.
Why does mowing or cutting alone fail?
The plant stores its energy below ground. Cutting removes the top and the rhizomes send up new shoots, often thicker than before. Cutting has a role, but only as part of a plan.
When is the best time to treat phragmites?
Late summer into early fall, after the plant has flowered. At that point it is moving sugars down into the rhizomes, and a properly labeled herbicide moves with them. Treating in spring mostly burns the top growth.
Do I need a permit?
Often. In New York, freshwater and tidal wetlands and the areas next to them are regulated, and applying herbicide in or over water generally requires an aquatic pesticide permit. Many towns have their own wetland rules as well. A contractor should determine what applies before quoting the work.
What does a full control plan look like?
- Confirm the plant and map the stand
- Determine wetland boundaries and required approvals
- Treat in the correct season with a product labeled for the site
- Cut and remove dead stalks where allowed
- Re-treat regrowth in years two and three
- Replant with native species so the stand does not return
Related: Wetland vegetation management | Invasive plant control | Aquatic services
This article is general information. Pesticides and repellents must always be applied according to the product label and state regulations.