Herbicidas para el control de Spermacoce tenuior L en papaya (Carica papaya)

herbicide perfomance for spermacoce tenuior l. control in papaya (carica papaya). in order to assess the effectiveness of pre and post-emergence herbicides for the control of spermacoce tenuior and other weeds in papaya, a field test was conducted in 2007, in a commercial field of the "pococí" hybrid, located in guápiles, limón, costa rica. a first phase of the study consisted of six post-emergent treatments (1. glyphosate 24 sl, 2. glyphosate 68 sg , 3. glip hosate 24 sl + carfentrazone 24 ec , 4. glyphosate 68 sg + carfentrazone 24 ec , 5. glip hosate 24 sl + metsulfuron methyl 60 wg, 6. gliphosate 24 sl + oxyfluorfen 24 ec). a second phase consisted of three pre-emergent treatments (1. oryzalin 75 wp, 2. oxyfluorfen 12 ec, 3. acetoclor 90 ec) distributed in a randomized complete block design in both phases. the percentage of weed ground cover, height and stem thickness of papaya plants were measured before and after herbicide app lication. post-emergence applications of glyphosate (0.94 kg i.a./ha) + metsulfuron (16 g i.a./ha) showed the best weed control from the second until the sixth week after application (waa ) without affecting the crop. oryzalin applied as a preemergent (3 kg i.a./ha) showed the best control of spermacoce tenuior until 14 waa under the planting row and around the plants. no phytotoxicity was observed.