Evaluación de herbicidas aplicados en pre y posemergencia en viveros de cacao (Theobroma cacao)

Five pre-emergence herbicides and sawdust and nine post-emergence herbicides, were tested for their efficiency and selectivity for weed control in cacao nurseries in Turrialba, Costa Rica. The plants were cultivated in black polyethylene bags (21 x 21 cm), with soil (80 percent) and sawdust (20 percent). The plots were treated two days after drilling with one of the following products: simazin (2.5 kg/ha), cianazin (2.5 kg/ha), diuron (1.5 kg/ha), liquid oxifluorfen (0.5 kg/ha), terbutrin (1.5 kg/ha) and sawdust (2 cm high). In the other experiment, the plots were treated 45 days after drilling with one of the following products: the same cited before, pelleted oxifluorfen (0.5 kg/ha), fluazifop-butil + bentazon (0.15 + 1.5 kg/ha), fenoxaprop-etil + bentazon (0.15 + 1.5 kg/ha) and bentazon + oil (1.5 kg/ha + 0.05 percent v/v), untreated and manual weed control. The set-up was a randomized-block experiment with four replicates, and 10 plants per plot. The herbicides in pre-emergence did not affect the cacao plants. However, the sawdust reduced the leaf area by 50 percent. All pre-emergence herbicides gave good weed control. In post emergence, all herbicides affected the cacao plants, but diuron and bentazon affected the most. Simazin and liquid oxifluorfen gave good weed control.