Residual effects of spraying imidazolinone-family herbicides on Clearfield®* sunflower production from the point of view of crop rotation

Abstract

SUMMARY This research was carried out to determine soil residual effects on stand establishment rate and yield in the rotation crops soft winter wheat ( Triticum aestivum L.), barley ( Hordeum vulgare L.), winter oil seed rape (WOSR) ( Brassica napus L.), maize ( Zea mays L.) and sugar beet ( Beta vulgaris L.) following Intervix® (33g Imazamox + 15g Imazapyr) spraying in Clearfield® (CL) sunflower ( Helianthus annuus L.) production. The experiments were conducted at the Trakya Agricultural Research Institute in Edirne between 2007 and 2009 using a randomized complete block design (stripe plots) with three replications. Five crops were evaluated in crop rotation after spraying Intervix® on Clearfield® sunflower. As the experiment materials, we used the sunflower hybrid Sanay-CL and the cultivars Gelibolu (soft winter wheat, SWW), Bolayir (barley), Elvis (winter oil seed rapeseed, WOSR), Brasco (maize), and Leyla (sugar beet). Nitrogen and phosphorus fertilization were applied according to soil analysis recommendations. Observations were made of the number of plants emerged per m2, stand establishment, yield, time to flowering, time to physiological maturity, plant height, root length, head diameter, etc ., according to plants included in crop rotations. Based on statistical analysis of the data from crop rotation experiments, CL sunflower plots followed by wheat, barley, and maize were not negatively affected to a significant degree by Intervix® residues in terms of stand establishment and seed yield in either year. In the first year of crop rotation, however, when planting WOSR four months after Intervix® application on CL sunflower plots, stand establishment and seed yield decreased significantly, by 35.7 and 23.7%, respectively. When planting sugar beet nine months after Intervix® application on CL sunflower plots, stand establishment and beet yield decreased by 26.7 and 11.6%, respectively. However, in the second year in the same crop rotations plots, stand establishment and yield of WOSR and sugar beet planted after CL sunflower were not affected significantly by Intervix® residues.