Giant Reed Identification & Treatment
Scientific Name: Arundo donax Category: Emergent Tier: 2 — Regionally Significant — Highly invasive
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Identification
Giant reed is a very tall (15–30 feet), bamboo-like grass with thick, hollow stems and broad, clasping leaves. It produces large, feathery plume-like seed heads. It is one of the tallest grasses in the world and can form impenetrable stands along waterways. Key distinguishing features:
- Very tall (15–30 feet), bamboo-like hollow stems
- Broad leaves (1–3 inches wide) with clasping bases
- Large feathery plumes at stem tips
- Forms dense, impenetrable stands
Commonly confused with: Phragmites (shorter, thinner stems, smaller leaves), Bamboo (woody stems, different leaf structure)
Treatment
Giant reed is extremely difficult to eradicate once established. Requires repeated, intensive treatment over multiple years.
- Glyphosate 5.4 — Apply to actively growing foliage late in the growing season (August–October) for best translocation to rhizomes.
- Imazapyr — Systemic herbicide effective on grasses. Can be combined with glyphosate.
- Cut-stump treatment — Cut stems and immediately apply concentrated glyphosate or imazapyr to cut surfaces.
Important: Mechanical removal alone is ineffective — rhizome fragments resprout aggressively. Chemical treatment of regrowth is essential.
Full Profile
- Native Range: Asia (possibly Mediterranean)
- US Distribution: Southern and western United States, especially California, Texas, and Southeast. USDA Zones 6–11.
- Regulatory Status: Listed as invasive in most states where it occurs.
- Habitat: Riparian areas, stream banks, pond margins, and wetlands.
- Reproduction: Primarily vegetative — rhizomes and stem fragments. Rarely produces viable seed in the US.
- Ecological Benefits: None in North America. Displaces native riparian vegetation, reduces wildlife habitat, increases fire risk, and consumes large amounts of water.
Sources: USDA PLANTS Database | USGS NAS
Related Species
- Phragmites (Common Reed) (Phragmites australis) — Emergent, Tier 1
- Cattails (Typha spp.) — Emergent, Tier 1
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