Believed to be a native plant to Asia, Green kyllinga was first reported in the country about 50 years ago. In the last 10 to 15 years, it has developed into a major problem for turfgrass and landscape managers. Green kyllinga is often mistaken as purple or yellow nutsedge, but its growth habits, reproduction, and morphology are different. The main problem with green kyllinga is that it grows in dense mats which can quickly take over a garden or lawn and be an eyesore. Kyllinga then makes little nutsedge seed heads which can make 5, seeds per year which grow all year round before going dormant in the wintertime.
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Glossary Mature green kyllinga plant. Green kyllinga, Kyllinga brevifolia, is a weedy sedge that is becoming a major problem in turf and ornamental plantings in California. The genus Kyllinga consists of about 40 species that are distributed worldwide in subtropical and warm temperate regions. Green kyllinga has been reported as a weed problem from Florida across the Southeastern United States into Arizona, California, and Hawaii. Green kyllinga is believed to have originated in Asia and was reported as a weed in California more than 50 years ago.
However, it has developed into a major problem for turfgrass and landscape managers during the last 10 to 15 years. Green kyllinga is sometimes confused with purple or yellow nutsedge, but its growth habits, reproduction, and morphology are different. Green kyllinga grows well in warm weather from April through October. When left unmowed, green kyllinga can reach a height of about 15 inches but will adapt and grow in a prostrate manner if mowed.
The plant produces a network of numerous underground stems rhizomes and can root and send out new leaves at each stem node. If green kyllinga rhizomes are removed and chopped into pieces, new plants can be produced from each node or stem section. Rhizomes in soil will begin to produce long, narrow leaves that are 1 to more than 5 inches long as temperatures rise in the spring. Green kyllinga stands out in turf due to its different texture and growth rate and is easily identified by its flower stalk.
Flowering usually occurs from May to October, but it can occur earlier in warm locations. Flower stalks are triangular in cross section and 2 to 8 inches long.
Directly below the flower is a group of three leaves that radiates out from the stalk. There are 30 to 75 spikelets within each flower, and each of these is capable of producing one seed. A mature plant can produce more than flowers within a growing season and up to 5, seeds.
The seed of the green kyllinga plant is highly viable and contributes significantly to the spread of this plant. Seed germination occurs at or very near the soil surface. Germination continues throughout the summer. Seedling growth is slow initially, and plants might require several weeks to become established. Once established, green kyllinga forms a vigorous system of rhizomes that allows lateral spread and production of new plants.
Green kyllinga can be confused with yellow or purple nutsedge because they grow in similar locations. Often green kyllinga can be recognized by its habit of growing in continuously enlarging patches similar to rhizomous turfgrasses.
Yellow and purple nutsedge appear more commonly as individual plants and have much wider leaves than the finer-bladed green kyllinga. Also, green kyllinga has a small, round seed head whereas nutsedges have an open spikelet. In turf it forms a weak sod that gives poor footing for athletic fields and golf courses. Although green kyllinga is most often a problem in bermudagrass , it has been found in cool-season turf species as well.
Green kyllinga has a texture and color that varies from normal turfgrass species and reduces the aesthetic quality of the turf. Also, green kyllinga grows faster than most turfgrass species, which gives infested turfgrass an undulating or irregular surface in as little as two days after mowing. Once a few plants become established in turfgrass or ornamental areas, spread can be rapid. In warm weather, rhizomes can grow by more than 1 inch per day, forming thick mats in just a few weeks. Mowing, foot traffic, and cultivation spread both seed and rhizomes.
This allows the production of new plants and hastens spread. Thoroughly clean mowers and cultivation equipment before moving from infested to weed-free areas. If solitary plants of green kyllinga are found, they should be grubbed out i. When green kyllinga infests ornamental plantings, it forms a dense mat that crowds out desirable species and reduces the vigor of those plants that survive. Because of the extensive rhizome system in established stands, hand pulling or hoeing to remove green kyllinga usually is futile unless done repeatedly over a long period of time.
Digging out plants and surrounding soil with a shovel is likely the best approach for removing rhizomes, although plant removal can be very expensive and not always successful. Once established green kyllinga will continue to spread unless control measures are taken. Turfgrass and ornamental areas should be well maintained to promote maximum vigor and make these plantings as competitive as possible to hinder invasion by the weed.
Dense turfgrass and ornamentals will shade the soil surface, making establishment of green kyllinga seedlings difficult. Irrigation systems should be adjusted and managed to eliminate wet conditions that favor green kyllinga. Turfgrass Controlling green kyllinga in turfgrass requires a combination of control procedures. Wet or overwatered areas in turfgrass provide ideal habitat for a green kyllinga invasion. If low areas stay wet, improve drainage or reduce water applications in that area.
Early grubbing of solitary infestations has been successful when practiced diligently. Spot spraying isolated plants with glyphosate can be helpful, but the turfgrass also is killed, leaving open areas that allow reestablishment of kyllinga or invasion of other weed species.
The open spots should be overseeded or patched with sod to establish a vigorous turf. Mowing and nitrogen fertilization also affect the growth of green kyllinga.
In one study on hybrid bermudagrass, low mowing i. Table 1.
How to Manage Pests
Key to weeds in turf Green kyllinga is a perennial sedge with narrow, grasslike leaves. In the warm season, green kyllinga grows more rapidly than most turfgrasses; its dense mats can even crowd out bermudagrass. Although it is most problematic in turf and ornamental plantings it also inhabits ditches and landscaped areas. In California it is found to about feet m in the Central Valley from Sacramento to Southern California, in the South and Central Coast regions from San Diego County probably to southeastern San Francisco Bay, but is not usually associated with agricultural land in the state. The plant grows best in moist or wet areas that receive full sun, but it can survive some shade and drying once established. Leaf edges and the lower midvein are sparsely covered with tiny barbs that are rough to the touch. Green kyllinga is dormant during the cool season, remaining green in mild-winter areas, and turning brown or purplish brown in colder regions.
Green Kyllinga Control: How To Get Rid of Green Kyllinga
Leaves few, basal or nearly so, blades herbaceous, linear, shorter than or occasionally as long as the culm, mm wide; sheaths brown or purplish brown, membranous. Inflorescence a single terminal spike or sometimes together, these pale green, more or less becoming yellowish green at maturity, globose or broadly ovoid-globose, mm long and as wide; involucral bracts 3, leaf-like, unequal in length; spikelets oblong-lanceolate, compressed, Achenes brown, obovate, lenticular, ca. It is one of the most common pasture weeds in Samoa" Whistler, ; p. In Fiji, "naturalized and often locally common from near sea level to 1, m in wet open places, swampy pastures, and cane fields, on rocks along streams in dense forest, river banks, hillsides and cleared mountain ridges, and along roadsides" Smith, ; pp. In Papua New Guinea "A plant of wet land, often seen in plantations and pasture.. In Tonga, "occasional in plantations and grassy areas" Yuncker, ; p.