Latin name

Actinoscirpus grossus (L. f.) Goetgh. & D.A. Simpson

Family

Cyperaceae

Common name(s)

Sedge

Synonym(s)

Scirpus grossus L. f. (basionym), Hymenochaeta grossa (L. f.) Nees, Schoenoplectus grossus (L. f.) Palla, Scirpus aemulans Steud., S. maximus Roxb.

Geographical distribution

Asia: China.

South and Southeast Asia: Cambodia, Indonesia, India, Lao PDR, Malaysia, Myanmar, Philippines, Sri Lanka, Thailand, and Vietnam.

Rest of the world: Australia and Turkey.

Morphology

A stout, strongly tillering perennial, up to 300—cm—tall, with long stolons that end in small tubers.

Stem: erect, sharply triangular, with concave sides smooth or slightly rough to the touch, thickened at base.

Leaf: basal and linear, upper half almost flat, acute and with very gradually tapering point; lower half keeled with 3 sharp projecting angles; 50—80—cm—long.

Inflorescence: 4—17—cm—long terminal corymb, composed of brown, ovoid, and 4—10—mm—long numerous spikelets.

Fruit: broadly obovate nut, smooth, light brown, and 1—1.5—mm—long.

Biology and ecology

Common in wetland rice, freshwater swamps, and along streams, canals, and drains.

Propagated by stolons and tubers, rarely by seeds.

Vegetative growth in rice fields is enhanced by increasing water depth to more than 10—cm. Flowering starts 18 weeks after sprouting.

Agricultural importance

Can cause serious losses due to its potential size even at low population densities.

Management

Cultural control: in preparation for rice, 2—3 rotovations and removal of stolons by harrowing reduce the population of this weed.

Chemical control: Paraquat, diquat, glyphosate, and glufosinate ammonium before crop is established provides control.

Selected references

Baki BB, Azmi M. 1992. Herbicide evaluation for weed control in direct-seeded rice in Peninsular Malaysia. Malaysian Appl. Biol. 21(2):1-10.

Kenji Noda, Teerawatsakul M, Prakongvongs C, Chaiwiratnukul L. 1985. Major weeds in Thailand. Bangkok (Thailand): Department of Agriculture. National Weed Science Research Institute Project. p. 142.

Kern JH. 1974. Cyperaceae. Flora Malesiana Ser. 1 7(3): 435-753.

Merrill ED. 1976. A flora of Manila. Manila (Philippines): Department of the Interior, Bureau of Science. 491 p.

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

Moody K, Munroe CE, Lubigan RT, Paller Jr. EC. 1984. Major weeds of the Philippines. College, Laguna (Philippines): Weed Science Society of the Philippines. University of the Philippines at Los Baños. 328 p.

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