Differences in sensitivity of F1 and F2 generations of herbicide tolerant sunflower volunteers to selected acetolactate synthase inhibiting herbicides

Abstract

The aim of this work is to describe the differences in sensitivity of Clearfield, ExpressSun and non-herbicide tolerant (HT) sunflower cultivars to several acetolactate synthase inhibitor herbicides and to find out the differences in sensitivity in F1 and F2 generations of these cultivars. Non-HT sunflower was very sensitive to most of the tested herbicides, except for nicosulfuron (efficacy 43–75%). F2 generation of non-HT sunflower showed a low level of sensitivity to imazamox (efficacy 10–43%) and to nicosulfuron, tribenuron, thifensulfuron and rimsulfuron under dry conditions (efficacy 43–83%). Sensitivity of Clearfield sunflower (cultivar with tolerance to imidazolinone herbicides) to tested sulfonylurea varied according to used herbicide and weather conditions. The highest efficacy on Clearfield sunflower showed iodosulfuron (97–100%) > florasulam (88–100%) > foramsulfuron (40–98%) > thifensulfuron (12–99%) > rimsulfuron (37–99%) > tribenuron (0–87%) > nicosulfuron (0–78%). ExpressSun sunflower (cultivar with tolerance to tribenuron) was the most tolerant to all tested herbicides. The lowest efficacy on F1 generation showed tribenuron (0%) > imazamox (0–17%) > nicosulfuron (0–43%) > thifensulfuron (0–57%) > rimsulfuron (0–70%) > foramsulfuron (8–75%) > florasulam (75–96%) > iodosulfuron (87–98%). Sensitivity of F2 generation of ExpressSun to tested herbicide was usually higher as compared to F1 generation.