What The Phrag?

Phragmites australis is an invasive plant in The State Of Delaware Controlling Its Growth Is A Challenge

Common throughout the State, and a something you see but never really think about, most of the Phragmites australis in Delaware is actually invasive. During the 1800’s, European strains of “Phrag”, also known as Common Reed, were introduced to the United States.

While the native strains grow intermixed with other plants and provides benefits to the ecosystem, the invasive is all bad news. Invasive Phragmites australis , creates large, dense, stands, known as monocultures. These large stands crowd out native species. Growing up to fifteen feet high, it blocks sunlight from reaching competing plants. It can alter the hydrology of our marshes and wetlands by turning open water into semi-dry land, and eliminating the marshes that dozens of species, including fish and birds use as nurseries. In addition, it increases wildfire risks; and actually emits a toxin that helps kill off native plants.

While it’s usually found in our wetlands, coastal environments, and tidal estuaries, it is actually not very tolerant of salt and moving water. It throws out huge root systems known as rhizomes, that can be hundreds of yards long. This root system is upland, out of salty, moving water. The mass of dead Phragmites australis, and its extensive roots create mats, that fill up quickly with soil, changing the coastline of the water it’s growing beside.

Because it has such an extensive root system, controlling Phragmites australis is a difficult task. The roots can grow several meters down into the soil and can spread as much as 10 feet in a season. Fire can eliminate the reed itself, and allow sunlight to reach native plants, however, as the plant mainly spreads through its rhizomes, this is only a temporary fix. Some success has been seen using a multi-pronged approach to management. This includes treating large stands with herbicide, so that the plant’s own vascular system transports the herbicide to the roots. After treatment, mechanical cutting can eliminate the standing plants, and fire can remove the reed mats.

While most people couldn’t imagine a beach trip without seeing it, Phragmites australis is damaging our ecosystem, every day.

Andrew Hansen, Wildlife/Forestry Conservationist, Naturalist