Control of Digitaria insularis (L.) Mez in Tropical Pastures

Abstract

Digitaria insularis, a grass weed unpalatable to cattle, adversely affects pasture production in the Markham and Ramu Valleys of Papua New Guinea.

Experiments revealed that on heavily infested pasture and fallow cultivated land it can be controlled successfully and further infestation restricted by establishing improved pastures. Proper management of both pastures and cultivated land is essential for continuing control. In productive pastures with light or patchy infestations it can be controlled by spot spraying of dalapon. Dalapon at 4–6 kg/ha (a.i.) on young stands (1-5 years) and at 6–8 kg/ha on old stands (5-10 years) in 1125 l/ha water sprayed on 3–4 week old regrowth after slashing or burning gave complete control. Higher rates are required if plants are sprayed without slashing or burning. Dalapon is most effective if applied when the plants are actively growing, with plenty of green foliage, usually after good rains.