Optimising Clearfield and ExpressSun sunflower technologies for Central European conditions

Abstract

The efficacy and selectivity of herbicides and tank-mix combinations at different application terms in Clearfield and ExpressSun sunflowers were evaluated. Five-plot field trials (2011-2015) were carried out in Prague. The efficacy of tribenuron (TBM) was excellent and quite rapid on Chenopodium album. Its efficacy on other tested dicot weeds ranged around 90%, depending on weather conditions and growth stages of weeds. Echinochloa crus-galli was not controlled by TBM. The tank-mix combination of TBM + propaquizafop (PQF) caused sunflower injury when applied in a very cold growing period. Under dry conditions, PQF efficacy on E. crus-galli was strongly reduced. The split application of TBM, when PQF was used at the second application, was less negatively affected by herbicide antagonisms. Very good results were obtained on plots with pre-emergence treatment with dimethenamid and post-emergence with TBM. The efficacy of imazamox (IZM) on dicot weeds was strongly affected by growth stages of weed and weather conditions during application. Efficacy of IZM on E. crus-galli was increased by oil adjuvant, but this adjuvant reduced IZM selectivity. The best efficacy, selectivity, and Clearfield sunflower yield were on plots with the split application of IZM.

Keywords

• helianthus annuus l.
• herbicide tolerant crop
• application date
• adjuvants
• herbicide antagonism