Family: Poaceae
Synonyms: Manisuris exaltata (l.f.)Kuntze, Rottboellia exaltata L.f.
Common names: Itchgrass, Corngrass, Prickle grass, Caminadora, Corredora, Sancaraña, paja peluda, Herbe à riz, Herbe à canne.An annual grass weed with a sturdy and erect culm, often tillering and rooting at the nodes, which can grow up to 3 m high. The inflorescence is a spike-like cylindrical raceme up to 15 cm long. The seeds are capsule-shaped containing grains.
Itchgrass currently occurs in more than 30 warm-climate countries of America, Africa, Asia and Oceania. The weed mainly thrives in moist permeable heavy-textured soils. According to the recent FAO Regional Workshop on Itchgrass Management (Managua, Nicaragua, May 1992), it is estimated that more than 3.5 million ha of crop areas are infested with itchgrass in Central America and the Caribbean.
The plant reproduces by seeds. A single plant may produce more than 3000 seeds. The seeds generally have some dormancy and fresh seeds require 4-5 months after-ripening before they germinate. Factors controlling dormancy include environmental factors and water-soluble phenols which inhibit germination. In warm weather conditions seeds can remain viable for over 2.5 years and at soil depths of 45 cm.
Methods to prevent itchgrass spreading to non-infested crop areas include the planting of clean certified crop seeds, the use of machines and implements free of itchgrass seeds and the total control of itchgrass patches in surrounding uncropped areas and along irrigation canals.
Deep cultivation during land preparation should be avoided as buried seed may remain viable for several years. Minimum tillage practices lead to more rapid depletion of weed seed.
In infested areas maize monocropping should be avoided. Soybean-maize rotation considerably reduces itchgrass infestation. Soybean and sweet potato have been recommended as effective preceeding crops in rotation with potatoes and beans for reducing itchgrass infestation.
