09 January 2012

Giant Reed, Arundo donax, threatens more than half of U.S.

http://threatsummary.forestthreats.org/images/maps/Giant_Reed_Map_73.png



 Giant reed is encroaching on waterways, international border access roads, and creating dense cover for illegal activities. The U.S. Department of Homeland Security has called for a plan to control it.
Giant Reed, Arundo donax,
is native to India and Mediterranean countries including Italy, Greece, Egypt, and Algeria.

Introduced into the U.S. in the 1800s as an ornamental, its common names include  Spanish reed, wild cane, cana brava, and carrizo.

This bamboo-like member of the grass family, grows 30 ft. high with deep, tough, fibrous roots.

" Blue-green alternate leaves are elongated, 1-2 in. wide and 12 in. long. Long, dense, plumes of whorled stemmed flowers reaching to 36 in. long occur during August and September. Seeds are not viable. Reproduction is primarily through rhizomes that root and sprout readily. Giant reed becomes established in moist places, growing best in well drained soils with available abundant moisture. It tolerates a wide variety of conditions, including high salinity, and can flourish in many soil types. It occurs on upland sites as scattered dense clumps along roadsides and forest margins. It forms dense thickets that choke riversides and stream channels, crowd out native plants, interfere with flood control, and reduce habitat for wildlife. Giant reed ignites easily and can create intense fires. Due to its rapid growth rate and vegetative reproduction, it is able to quickly invade new areas and form pure stands and, once established, can out-compete and completely suppress native vegetation."

IAPMS - Invasive Plant Atlas of the Mid-South
This vegetation threatening our watersheds also has stems and leaves containing several toxic or unpalatable chemicals, which can discourage native insects and other grazers from helping to reduce its numbers. It is, however, a good candidate for biological control methods. The eurytomid wasp has been tested in a small area of release and found to be a specific enemy to the giant reed, and unlikely to harm native plants.

Other plants commonly called Giant Reed are also invasive.
For example, the Illinois wildflower called Giant Reed is Phragmites australis. Its native range includes North America, Eurasia, Africa, and Australia. In optimal wetland conditions it can choke out other plant species.
If you find Arundo donax growing on your property, eradicate it.

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