Efficacy of primextra gold in controlling weeds of melon (Citrillus lanatus (Thunb.) Matsun and Nak.)
A field experiment was conducted in the Center of Ecological Studies, University of Port Harcourt, Rivers State to evaluate the efficacy of Primextra Gold (290g /l S – Metalochlor and 370g/l Atrazine) herbicide in controlling weeds in melon and to determine its safety for use in melon. The experiment was carried out between the months of February and March, 2013 and was laid out in a completely Randomised Design with four replications. Seven weed control treatments – 0.0, 0.25, 0.5, 0.75, 1.0, 1.25and 1.5 kg a.i/pot – were applied post plant, pre-emergent for this study. The dry weight, height of plant, number of green leaves, weed control efficiency, weed persistence index, crop phytotoxicity rating, weed destruction rating, weed count (total number of weeds), weed flora and classification were used to determine the herbicide efficacy and crop safety. Results show that the effects of the treatments were mostly significant; treatments higher than 0.75kg a.i/pot were more toxic to the melon. Injury caused by lower treatments (0.25 – 0.75kg a.i/pot) to the melon reduced over time while injury caused by higher treatments (1.0 – 1.5kg a.i/pot) increased over time. Treatment 0.75kg a.i/pot resulted in the highest height (72cm/pot), highest number of leaves (20.3/pot), second highest dry weight (2.98g/pot) at 28 DAT. The study also showed that Primextra Gold has a high Weed Control Efficiency (WCE %) and the Weed Persistence Index (WPI) of the weeds was low. The most common weeds observed were Oldelandria corymbosa, Phyllantus amarus, Oplismanus burmanii and Digitario sp., as they occurred in the untreated pots and in virtually all treated pots.
Key Words: DAT- Days-after-treatment, Primextra Gold, Melon, weed control efficiency, weed control treatments.