Experiments were conducted in Sri Lanka to compare weed seedling emergence in three sugarcane plots of 0.1 ha planted in October 1995, January 1996, and April 1996. In each plot, weed seedling emergence was monitored for 20 wk in five permanent quadrats on each of three microsites: on ridges, in furrows, and on adjacent fallow land. Soil moisture (0 to 5 cm) and soil temperature (at 2.5 cm) were also recorded. Only crowfootgrass, swamp millet, and guineagrass (all grasses) occurred in all nine planting time-by-microsite combinations. About half of all seedlings emerging over the three planting times were swamp millet, and the next most frequent species was tropic ageratum. The composition of the emerged flora was similar on ridges and in furrows, but more seedlings emerged in the furrows than on the ridges. The highest number of emerged seedlings and of species occurred on adjacent fallow land. The major factor influencing seedling emergence appeared to be soil moisture.
Nomenclature: Crowfootgrass, Dactyloctenium aegyptium (L.) Willd. DTTAE; guineagrass, Panicum maximum Jacq. PANMA; swamp millet, Isachne globosa (Thunb.) O.Kuntze ICHGL; tropic ageratum, Ageratum conyzoides L. AGECO; sugarcane, Saccharum officinarum L. SACOR.