Introduction:
Crowtoes (Lotus corniculatus) Weeds.
Lotus corniculatus (bird’s foot trefoil) is a low growing perennial legume that has long been valued as an agricultural crop. Lotus corniculatus is native to much of Europe, Asia and parts of Africa, but now has a near global distribution. Over most of its range, Lotus corniculatus is not considered invasive, although in a few areas it has out-competed native vegetation.
Description:
Lotus corniculatus is a perennial, herbaceous member of the pea family (Fabaceae). It can be distinguished from all other members of the pea family by its five leaflets and head-like umbels of bright yellow flowers. L. corniculatus blooms from May-September in the United States. The root system includes a long tap root, which may be longer than 3 feet, and a fibrous mat near the soil surface consisting of secondary roots, rhizomes, and modified stems.
The stems of L. corniculatus are nearly square, erect or sprawling on the ground, branched, either smooth or sparsely hairy, and up to one and a half feet long. Numerous stems arise from a basal, well-developed crown with branches arising from leaf axils. The leaves are alternate and pinnately compound. The leaflets are somewhat hairy, smooth, elliptic, rounded or pointed at the tip, and tapering to the base. They are up to 2/3 an inch long and 1/3 an inch wide, and lack stalks. The flowers are up to 2/3 an inch long, with ten stamens and superior ovaries. “Ripe pods are cylindrical, 15-30mm long, 2-3mm wide, brown to almost black, borne at right angles to the top of the peduncle (hence ‘bird’s-foot’ trefoil as the common name). Seeds are irregularly rounded, somewhat flattened, 1.3-1.5mm long, variable in colour at maturity, olive to brownish to almost black, frequently speckled and shiny. Seeds are ejected from the pods as the pods rupture at maturity, averaging 375,000 seeds per pound.
Occurs in:
Agricultural areas, coastland, ice, ruderal/disturbed, vector.
Crowtoes (Lotus corniculatus) Distribution in North America shown in green.
Habitat description:
Lotus corniculatus thrives in temperate regions, inhabiting roadsides, old fields, and other disturbed soils. In the British Isles, L. corniculatus is “widespread in grasslands and species-rich heath; also found on cliffs and as a pioneer in quarries and on roadside verges. It is “adapted to loam soils with good moisture holding capacity and also to heavy clay soils. It is not adapted to sandy soils. High soil temperatures appear to favour root diseases. Legume of choice where drainage or acidity are a problem. It will tolerate low levels of fertility but is productive only on soils with good fertility. Birdsfoot trefoil is a slow growing perennial legume adapted to cooler climates. It is slow to establish and being a light loving plant will not withstand much competition at the seedling stage. It can tolerate a pH range of 5.5-7.5, and performs well on shallow or poorly drained soils compared to alfalfa. A study in Australia showed that L. corniculatus has “important potential for low fertility acidic soils on tablelands and slopes where the Australian Annual Rainfall is 650-1000mm, especially in northern New South Wales. Although L. corniculatus prefers to grow in warm, moist places, it is intolerant of being inundated with water for prolonged periods.
General impacts:
Lotus corniculatus forms dense mats which choke out and shade native vegetation. It grows well in the arid midwest US and is problematic in prairies and open or disturbed areas such as roadsides. Prescribed burns facilitate seed germination, which threatens native prairies. One study reported that suspected photosensitization occurred in
Close up of the Crowtoes (Lotus corniculatus) Weed.
lambs grazing L. corniculatus. One group of sucking lambs developed skin lesions on the back and ears. The tips of the ears in a few animals were shortened by 2-3 centimeters.
Management information:
Physical: To control small infestations of L. corniculatus, dig up plants by roots, making sure to remove all root fragments. For larger infestations, frequent mowing (more than once every 3 weeks) at a height of less than two inches for several years helps to control the plant but may set back native plants. Controlled burns of L. corniculatus are not recommended because they increase seed germination and promote seedling establishment.
Chemical: L. corniculatus can be effectively controlled with general use herbicides such as: clopyralid, glyphosate, and triclopyr. Morfamquat, ioxynil plus mecoprop, 2,4-D-mecoprop, dichlorprop, fenoprop, and dicamba are effective herbicide treatments on L. corniculatus, while MCPA-salt, 2,4-D-amine and ester have no effect. Acumen and basagran MCPB are considered very toxic herbicide treatments for L. corniculatus seedlings. Considerable damage to seedlings was caused by: brasoran, gesagard, and opogard; EPTC was considered an ineffective treatment. L. corniculatus showed no response to carbofuran or benomyl. “Spot spraying affected areas, (after re-greening from a burn or mowing), with clopyralid + surfactant + dye. This selective herbicide also affects native plants of the sunflower and pea families.
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