History & Introduction

A native of the Mediterranean, Ravenna grass is named after the town of Ravenna, Italy. It was introduced to the U.S. as an ornamental plant, as early as 1921. The plant is escaping cultivation and invading natural areas. In the U.S, it is a problem predominantly in the West, although populations are scattered across the country. It may increase its range and should be watched closely. 

Ravenna grass grows in moist places such as ditches, marshes, wetlands, and riparian areas. It tolerates a wide range of conditions. In California, it was noted to be growing in much of the same type of habitat as common reed, (Arundo donax), and saltcedar, (Tamarix parviflora). 

In New York, Ravenna grass is a Tier 2 species listed for early detection and eradication. It is currently reported at a utility right of way in Suffolk County. There are no other known reports in LIISMA. 

Identification & Biology

Ravenna grass is a large, erect grass that can reach 14 ft. in height with flowering, cane-like plumes. Its clump size can be up to 7ft. In diameter. The leaves are distributed along the stem, up to the plumes. It is very densely covered with long, fuzzy hairs at the base of each leaf. The underside of the leaf displays a white midvein running the length of the leaf blade. Ravenna grass leaves are minutely serrated but not sharp and its stems resemble bamboo-like stalks that are pale, silvery and feathery on the tips. Stems can grow up to 14ft. in height, appearing in late summer to early fall. Seed head plumes produce thousands of tiny seeds that can be dispersed long distances by wind and water. Its root system is very dense and diffuse. 

Damage & Concern

This species is aggressive, persistent and spreads rapidly. It establishes itself readily with little disturbance required, putting intact plant communities at risk. It can quickly take over disturbed areas, outcompeting native species and reducing plant diversity and wildlife habitat. It can form vast, impenetrable monocultures and is very difficult to eradicate. This species may have higher water usage than some native riparian or wetland species because it possesses a large leaf surface area. Expansive populations have the potential to change riparian vegetation and stream characteristics in wetland habitats. Can be a wildfire hazard. Established stands may bring fire into riparian zones and anchor soils normally subject to shifting. Ravenna grass can also act as a physical barrier to stream flow.

Management & Control

Manual Removal:

Plants can be hand dug out of the ground, but it is important to remove the roots and rhizomes to prevent resprouting. Plants will resprout after burning, cutting or grazing, so follow-up control will be needed if the roots are not removed. If it isn’t possible to remove all plants before seeds develop, consistently removing plumes before seeds mature will help to prevent population expansion. However, plants that have had plumes removed may develop more plumes during the flowering season, so follow-up plume removal may be needed. Bag and remove plumes to prevent seed development on site. The grass will produce more plumes, so the plants should be checked for new flowers until the first frost of the fall. Use gloves when handling the plants to avoid contact with the serrated leaves.

Chemical Control:

Most control efforts use spot treatments of a 5% glyphosate solution of Rodeo or Aquamaster. Application should be done post-emergence, to fully mature plants, but before flowers produce viable seeds. This is likely during the early summer months. Glyphosate is a non-selective herbicide with no soil activity. It has proven to be the most effective chemical control option for Ravenna grass. There have also been reports that a 5% glyphosate solution mixed with 1% imazapyr (Habitat) will give very effective control. When using any chemical control, always read the entire pesticide label carefully, follow all mixing and application instructions, and use all personal protective gear and clothing specified.

Monitoring & Reporting 

LIISMA is currently monitoring Ravenna grass as part of our Early Detection and Rapid Response program. As reports of the species are collected, LIISMA is dedicated to delineating and managing any early emerging infestations of the species before they become widespread. Ravenna grass is currently a Tier 2 species on Long Island, prioritized for early detection and containment. 

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