Selectivity of the herbicide metribuzin for pre- and post-emergence applications in potato cultivation

Metribuzin is the most commonly used herbicide in potato cultivation in Brazil, but there are few reports in literature regarding its selectivity, especially when applied to post-emergent potato plants. The objective of this study was to evaluate the selectivity of the herbicide metribuzin for potato cultivation, applied in pre-and post-emergence. Two experiments were carried out under field conditions, one with the Agata cultivar and another with the Atlantic cultivar. A randomized block experimental design, with a subdivided plot (5 x 3) and four replications, was used in both experiments. Plot experiments consisted of five doses of metribuzin (0, 120, 240, 360, and 480 g a.i. ha(-1)), studied for pre-emergence, as well as three doses (0, 120, and 192 g a.i. ha(-1)) studied for post-emergence. Metribuzin was selective for the Agata and Atlantic cultivars at doses of up to 480 g ha(-1) for pre-emergence, as well as at 120 or 192 g ha(-1) for post-emergence, applied seven days after hilling.