The objectives of this study were to determine the response of sunflower to application of boron (B) fertilizer and herbicides, alone or in combination, and to determine its weed control. A field experiment was carried out at Embrapa Soja, Londrina, Parana, Brazil. The treatments were acetochlor (1.92 kg a.i. ha-1), oxyfluorfen (0.36 kg a.i. ha-1), sulfentrazone (0.35 kg a.i. ha-1), trifluralin (1.80 kg a.i. ha-1) and two controls (with and without hoeing). All treatments were applied alone or in combination with 2 kg ha-1 of B (Na2B4O7.10H2 0 - borax and H3BO3 - boric acid). Acetochlor plus boric acid was the most efficient treatment. Herbicides mixed with boric acid provided a more homogeneous aqueous suspension when compared with herbicides plus borax. Acetochlor applied alone or in combination with two B sources was efficient in controlling wandering jew (Commelina benghalensis), hairy beggarticks (Bidens pilosa) and morning glory (Ipomoea grandifolia). Oxyfluorfen and sulfentrazone applied alone or in combination with the B sources were efficient in controlling wild poinsettia (Euphorbia heterophylla) and morning glory (Ipomoea grandifolia), respectively. The application of B with herbicides in tank-mixes is a good strategy for avoiding B deficiency and controlling weeds in sunflower crop.
Helianthus annuus; chemical control; weeds; micronutrient
