Seletividade de herbicidas aplicados em pré-emergência em cultivares de girassol

Abstract

The difficulty in managing weeds present in sunflower increases together with the crop expansion, mainly due to the few selective herbicide options. In this sense, the objective of this research was to evaluate the selectivity of the Olisun 3 and ADV 5504 sunflower cultivars to the herbicide treatments applied in pre-emergence of the crop under field conditions. The experimental design was a randomized block, 2 × 6 factorial scheme in four replicates, two cultivars (Olisun 3 and ADV 5504) and six herbicides (sulfentrazone 600 g i.a. ha-1, s-metolachlor 1920 g i.a. ha-1, trifluralin 1780 g i.a. ha-1, prometryn 1000 g i.a. ha-1, flumioxazin 40 g i.a. ha-1 and a non-treated control). The phytotoxicity (medium of 6.92 and 10.96%) in the plants was observed with 7 DAA. The ADV 5504 cultivar showed higher values of phytotoxicity (14.75%) for the herbicide S-metolachlor. Olisun 3 exhibited the largest stem diameter (23,32 mm) when prometryn was used. For head insertion height, ADV 5504 presented a higher value (1.16 m) and the herbicide S-metolachlor did not affect this variable, with a value (1.15 m) statistically similar to the control. The yield of the two cultivars was statistically similar (1891.28 and 2025.91 kg ha-1). All herbicides researched were selective to both Olisun 3 and ADV 5504 cultivars, not interfering with the final yield of sunflower grains. Therefore. it is possible to recommend these products to control weeds in this crop.