Control of Parthenium hysterophorus L. and its impact on yield performance of tomato (Solanum lycopersicum L.) in the northern province of Sri Lanka

Impact of weed control methods on the persistence of Parthenium hysterophorus L. , and tomato ( Solanum lycopersicum L. ) yield was studied in two farmer fields i.e. a site heavily infested with P. hysterophorus (Parthenium-site) and Parthenium free site, in the Jaffna peninsula of the Northern Province of Sri Lanka. The split-plot design consisted of two main plots i.e. manual weeding and ploughing (both followed by harrowing), and three sub-plots i.e. use of a pre-emergent herbicide (Oxyfluorfen; 240 g/L EC at 2 days before planting), mulching [ Gliricidia sepium (Jacq.) Kunth ex Walp. leaves at 12 kg per plot on fresh weight basis], and un-weeded plot after crop establishment (control), in three replicates. The soil seed bank of the Parthenium-site was dominated by P. hysterophorus as expected, and the Parthenium-free site was dominated by the perennial sedge Cyperus rotundus L. At tomato harvest, the un-weeded sub-plots recorded the highest weed densities (p G. sepium coupled with manual weeding during land preparation or ploughing would suppress growth and development of weeds including P. hysterophorus and enhance yield of tomato. Tropical Agricultural Research Vol. 25 (1): 56-68 (2013)