History & Introduction
Weeping lovegrass is a warm season perennial bunchgrass first introduced from South Africa into the United States in 1934 for erosion control and livestock feed. It has since been introduced in several states, including New York in 1965. Since its original introduction into Oklahoma, it is now also common in Arizona, New Mexico, and Texas, southern New York, and is becoming common in New Jersey, Pennsylvania, and other eastern states. Through much of the 20th century, weeping lovegrass was used extensively as erosion control due to its extensive mat forming roots, where it thrived on nutrient poor, acidic, and disturbed sites. As a result of its hardiness, it was introduced to wildlife refuges, mine spoils, and sand dunes in efforts to vegetate these “harsh” environments and sequester heavy metals. From the 1960s – 1980s, The NYS Department of Transportation planted weeping lovegrass along Long Island roadsides. This includes plantings along Sunrise Highway and the Long Island Expressway, which ultimately led to its establishment on the sandy soils of Suffolk County, which was first documented in 2000. Concerns about the negative impacts of this species were first noted in 2002 due to its ability to form monocultures and exclude native plants.
Identification & Biology
This perennial warm season grass grows in tight tufts up to four feet in height with distinct drooping leaves nearly touching the ground, granting its name “weeping” lovegrass. Long, narrow leaves (3 – 4 mm wide) may be up to two feet in length but rarely stand at over 12 inches in height. Leaf margins may be rolled inward or flat. Leaves are rough on both sides and foliage ranges from green to blue-green. Each open panicle seed head with spikelets may produce up to 1000 seeds and rise to 30 – 40 inches. Spikelets have 4 – 15 florets and are yellowish at maturity. Weeping lovegrass may have two crops of seeds per season, once in spring and a second, smaller crop in early fall. The ligule, where the leaf sheath meets the blade, is hairy or ciliate, as are the leaf sheaths along the collar and upper margin. Weeping lovegrass does not require fertilization, as it is an obligate apomictic species. It has a thick, fibrous root system that penetrates up to 15 feet deep in the soil and 3 feet laterally. It does not spread vegetatively and relies on seed production to spread.
Weeping lovegrass is tolerant of a range of environmental conditions and can be found in several habitats. It is cold, salt, and heavy metal tolerant and can tolerate a wide range of soil acidity. It is only minimally affected by fire, with its tight basal leaves shielding the plant from burning. Plants continue to sprout after a fire, and seed recruitment is likely following a fire. Weeping lovegrass can be found on roadsides, mine spoils, old fields, grasslands, chaparral, prairie, forest edges, pine-oak, and mixed hardwood woodlands.
Many cultivars and ecotypes of weeping lovegrass were imported and are in the landscape today. Similar species, such as Lehmann lovegrass (Eragrostis lehmanniana), can appear nearly identical to weeping lovegrass, although Lehmann lovegrass tends to be slighly smaller and lacks hairs on its leaves and membranes. Leaves may also lay prostrate on the ground rather than droop towards the ground. Lehmann lovegrass is more likely to spread beyond its planted range but remains less abundant than weeping lovegrass overall due to the mass plantings of weeping lovegrass in the 20th century. Weeping lovegrass can also hybridize with other Eragrostis species, including Eragrostis caesia, E. lehmanniana, and E. planiculmis.
Damage and Concern
Weeping lovegrass is a heavy seeder, setting seed once or twice per growing season and producing 1000 seeds per panicle, each plant producing multiple panicles. Its seed is known to spread by wind, water, animals, and human activity including on vehicles. Its ability to spread great distances by seed is poorly understood and has been observed spreading into some natural areas but may also only increase in density and at its original planting sites and not spread beyond. As climate change progresses, conditions may become increasingly suitable for weeping lovegrass and the incidence of its spread into natural areas may increase. Further research is needed to understand its ability to spread.
Due to its desirability for erosion control and livestock grazing, weeping lovegrass is abundant in several states and on Long Island. According to the USDA, weeping lovegrass has “formed monocultures in late-seral old fields and occurs in maritime grasslands in Shinnecock Hills, which are considered a globally rare ecosystem by the New York Natural Heritage Program [61].” Maritime grasses are now uncommon on Long Island, and those that remain are often degraded and abundant with invasive species. Although weeping lovegrass is widespread, suppressing this species may be an important part of maritime grassland conservation and restoration efforts.
Weeping lovegrass has also been a likely contaminant of seed mixes. Where it has been planted on mine spoils and for erosion control, it inhibits the recruitment and regeneration of native grasses and is a highly competitive species. When researchers compared weeping lovegrass to other non-native grasses and legumes, it exhibited rapid emergence and behaved aggressively under ideal conditions. Studies have also indicated that native forbs, shrubs, and especially grasses are present in less abundance when weeping lovegrass is present, and species richness is lower due to its tendency to form monocultures. It is also a less preferred habitat for many wildlife species, with stands of weeping lovegrass having reduced diversity of grassland birds and small mammals.
Management
Manual/Mechanical Control:
Due to its extensive root systems and ability to stabilize soil, manual removal of weeping lovegrass may result in erosion and soil destabilization. Hand removal can be best implemented after a rain if possible, when plants are young, and temperatures are cool early in the growing season. Hand pulling, hoeing, or digging may be effective manual removal techniques.
Repeat treatments and follow-up may be necessary, especially after rain when new plants may have emerged. It is necessary to continue manual removal for several years to suppress this species and deplete the seed bank. Properly dispose of any plant material with seeds by bagging and disposing off site.
Tilling and mulching have been effective for removing undesired weeping lovegrass from pasturelands due to its sensitivity to light. Seeds will not germinate when covered and plants will quickly respond to a lack of light. Mulching or solarizing could be adapted to control weeping lovegrass in natural settings.
Mowing can be effective when close cutting is performed to deplete carbohydrate stores at the crown of the plant. It is recommended to cut to a height of 2 inches and to leave debris in place. Mowing is most effective when implemented from September through November.
Although weeping lovegrass is fire resistant, burning to reduce biomass followed by chemical treatment may be effective in treating monocultures.
Chemical Control:
Weeping lovegrass can be controlled with a foliar spray of glyphosate or imazapyr based products. Treatment is most effective when the plant is 80% or more green foliage. Due to its phenological advantage of emerging before and persisting longer than native grasses, a small window for treatment is available in which off-target impacts may be avoided. If treated alongside the presence of native species, avoid broadcast herbicide application and instead treat individual plants of weeping lovegrass. Always follow herbicide labels, state and local regulations, and best management practices to minimize harm to surrounding vegetation and wildlife.
Cultural Control:
Due to its persistent nature, it may be difficult to restore grassland communities in which weeping lovegrass is dominant. The USDA recommends maintaining healthy plant communities to help prevent or limit new infestations of weeping lovegrass. Prevention and excluding undesirable plants from priority areas can also be an effective tool in limiting the overall damage caused by this plant. Mowers and other equipment along with materials that may be contaminated with seed should be thoroughly cleaned and inspected to minimize the spread of weeping lovegrass seed.
Biological Control:
In Arizona, grazing has been used to suppress weeping lovegrass. It is mildly palatable and therefore grazing is most effective in winter and spring before native grasses have emerged. In Oklahoma, grazing is most effective in controlling weeping lovegrass in fall. Further research is necessary to determine the effectiveness of grazing in Northeast climates and ecosystems.
Below are USDA management recommendations for lovegrass species, including Lehmanns and weeping.
Monitoring and Reporting
LIISMA is currently monitoring weeping lovegrass as a Tier M (Tier 5) species to gather more data about its distribution and impact. As reports of the species are collected, LIISMA is working with partners to delineate and manage any early emerging infestations before they become widespread.
Your reports matter to us – please report the species to iMapinvasives or iNaturalist as soon as you detect it.
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Citations
Eragrostis curvula. (n.d.). https://www.fs.usda.gov/database/feis/plants/graminoid/eracur/all.html#Distribution%20and%20Occurrence
Field Guide for Managing Lehmann and Weeping Lovegrasses in the Southwest. Share your feedback on Acrobat DC. (n.d.-a). https://acrobat.uservoice.com/forums/931921-adobe-acrobat-in-browsers/suggestions/47606612-chrome-extension-efaidnbmnnnibpcajpcglclefindmka
Plant Fact Sheet WEEPING LOVEGRASS Eragrostis curvula (Schrad.) Nees . Share your feedback on Acrobat DC. (n.d.-b). https://acrobat.uservoice.com/forums/931921-adobe-acrobat-in-browsers/suggestions/47606612-chrome-extension-efaidnbmnnnibpcajpcglclefindmka
Weeping Lovegrass. Weeping lovegrass: Eragrostis curvula (cyperales: Poaceae): Invasive plant atlas of the United States. (n.d.). https://www.invasiveplantatlas.org/subject.cfm?sub=6989
