Latin name

Paspalum distichum L.

Family

Poaceae

Common name(s)

Knotgrass

Synonym(s)

Digitaria distichum (L.) Fiori & Paol., D. paspaloides Michaux, Milium distichum (L.) Muhl., Paspalum distichum var. indutum Shinn., P. paspaloides (Michaux) Scribner, Panicum paspaliforme J. Presl

Geographical distribution

Asia: China (including Taiwan) and Japan.

South and Southeast Asia: Bangladesh, Bhutan, India, Indonesia, Malaysia, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, and Vietnam.

Rest of the world: Argentina, Australia, Brazil, Chile, Colombia, Ecuador, Egypt, England, Fiji, France, Guyana, Honduras, Iran, Iraq, Israel, Italy, Jamaica, Jordan, Mauritius, Melanesia, Mexico, Micronesia, Morocco, New Zealand, Peru, Portugal, Puerto Rico, South Africa, Soviet Union, Spain, Suriname, Swaziland, United States (including Hawaii), Uruguay, Venezuela, and West Polynesia.

Morphology

Perennial grass up to 30—cm—tall with creeping, branched stolons.

Stem: culms erect, solid; nodes thickened and hairy.

Leaf: blades 5—15—cm—long, without hairs; sheath with hairy margins; ligule membranous and fringed.

Inflorescence: two to 6—cm—long racemes; spikelets solitary, obovate-oblong, about 3—mm—long.

Close-up of panicle (IRRI).
Fruit: yellowish to light brown, compressed and ellipsoid caryopsis.

Biology and ecology

Grows in moist areas and frequently flooded lowland areas and is an important weed of several crops. Capable of rapid growth and propagates vegetatively by stolons and rhizomes that survive dry periods; stem also produces roots if they touch the soil.

Agricultural importance

Paspalum distichum is a weed of legumes, maize, rice, root crops, and vegetable crops.

Management

Cultural control: Paspalum distichum can be controlled by 2 or 3 harrowings during land preparation for transplanted rice.

Chemical control: Glyphosate and butachlor reported to be effective.

Selected references

Holm L, Pancho JV, Herberger JP, Plucknett DL. 1979. A geographical atlas of world weeds. New York (USA): John Wiley & Sons, Inc. 391 p.

Janiya JD, Moody K. 1988. Effect of time of planting, crop establishment method, and weed control method on weed growth and rice yield. Philipp. J. Weed Sci. 15:6-17.

Janiya JD, Fajardo FF, Moody K. 1989. Control of Paspalum distichum L. in transplanted rice. Philipp. J. Weed Sci. 16:49-59.

Manuel JS, Mercado BL. 1977. Biology of Paspalum distichum I. Pattern of growth and asexual reproduction. Phil. Agron. 61:192-198.

Manuel JS, Mercado BL, Lubigan RT. 1979. Approaches to the control of Paspalum distichum L. in lowland rice. Phil. Agr. 62:255-261.

Mercado BL, Manuel JS, Lubigan RT. 1977. Biology and control of Paspalum distichum L. III. Competition with lowland rice. College, Laguna (Philippines): Dept. of Agronmy, University of the Philippines, Los Baños. Weed Science Report 1976-1977. p 24-28.

Moody K. 1989. Weeds reported in rice in South and Southeast Asia. Manila (Philippines): International Rice Reseach Institute. 442 p.

Pablico PP, Moody K. 1986. A dry season lowland rice (Oryza sativa) weed survey in Central and Southern Luzon, Philippines. Philipp. J. Weed Sci. 13:39-49.

Pancho JV, Obien SR. 1995. Manual of ricefield weeds in the Philippines. Muñoz, Nueva Ecija (Philippines): Philippine Rice Research Institute. 543 p.

Soerjani M, Kostermans AJGH, Tjitrosoepomo G. 1987. Weeds of rice in Indonesia. Jakarta (Indonesia): Balai Pustaka. 716 p.

Contributors

JLA Catindig, RT Lubigan, and DE Johnson