From noncultivated areas to the field: a case of cut-leaved gipsywort (<i>Lycopus exaltatus</i> L.) and its response to herbicides in Balkan major crops

Abstract Certain plant species have the potential to establish themselves in agricultural fields, especially when they are already present nearby. Their spread can be influenced by improper management or intentional and unintentional introduction. Recently, cut-leaved gipsywort ( Lycopus exaltatus L.) has been increasingly present in some row crops, where it was previously found only along field edges and irrigation channels, with no data about their presence in crops. Currently, no effective control methods for this rhizomatous species have been reported. To address this, 11 herbicides commonly used for weed management in major crops were evaluated in greenhouse studies. These included bentazon, dicamba, foramsulfuron, glyphosate, halauxifen-methyl, imazamox, mesotrione, nicosulfuron, tembotrione, thifensulfuron-methyl, and tribenuron-methyl. A dose-response study was conducted to identify the most effective option for cut-leaved gipsywort control using existing crop protection products. The study evaluated percentage reductions in dry biomass and canopy cover. The results suggest that bentazon, as the only nonsystemic herbicide, was least effective in controlling cut-leaved gipsywort with an effective dose (ED 90 ) estimated at 1.5 × of the recommended labeled rate, or 2,205 g ai ha −1 . Plants exposed to dicamba exhibited no regrowth at the field-use rate. Cut-leaved gipsywort may regrow when foramsulfuron, mesotrione, nicosulfuron, and tembotrione are applied at the recommended field-use rates. Halauxifen-methyl and imazamox were most effective, with estimated ED 90 values of 0.21 × (0.85 g ai ha −1 ) and 0.4 × (16.14 g ai ha −1 ), respectively, which are lower than the recommended labeled rates. Although reduced rates are not recommended because good herbicide stewardship practices should aim to prevent the development of herbicide resistance, with both halauxifen-methyl and imazamox, cut-leaved gipsywort exhibited no regrowth when one-half of the recommended labeled rates were applied.