ABSTRACT Sustainable alternatives to synthetic herbicides are increasingly needed in legume cropping systems, driven by the growing demand for organically produced grain legumes (where synthetic herbicides are prohibited) and the very limited number of chemical herbicides registered for conventional grain legume production. This study evaluated the herbicidal potential of ethanolic plant extracts for controlling common chicory ( Cichorium intybus L.) in chickpea ( Cicer arietinum L.) crops during the 2021–2022 and 2022–2023 seasons in Kermanshah, Iran. Foliar treatments included ethanolic extracts of chamomile ( Anthemis odontostephana Boiss.), tumble thistle ( Gundelia tournefortii L.), and peanut ( Arachis hypogaea L.) shell, pelargonic acid, Challenge herbicide (aclonifen), and a distilled water control. GC–MS analysis was performed only on the chamomile extract, which exhibited the highest herbicidal efficacy, to identify key bioactive compounds responsible for its superior weed suppression. Chamomile extract provided the strongest weed control, increasing chickpea biomass by up to 55.53% and reducing chicory biomass by up to 73.81% relative to the control 2 weeks after application. It achieved the highest weed control ability (91%–94%) and caused the greatest reductions in chicory chlorophyll content (down to 16.13 SPAD units vs. 50.6 in control) and stomatal conductance (64%–75% reductions). GC–MS of the chamomile volatile fraction identified 21 compounds, with myrtenyl acetate, decanoic acid, spathulenol, and caryophyllene oxide predominant. These findings demonstrate that chamomile ethanolic extract, rich in terpenoids such as myrtenyl acetate, shows strong potential as a natural bioherbicide for sustainable management of common chicory in chickpea. Given the widespread occurrence of C. intybus as a problematic weed in various grain legume crops worldwide, this extract may warrant further evaluation in other legume cropping systems.
Jalilian et al. (Wed,) studied this question.