Tolerance of plantain (Plantago lanceolata) to translocated herbicides wiped on flower stems

Abstract

ABSTRACT Growing plantain (Plantago lanceolata) within pastures reduces nitrate leaching following grazing. Plantain is usually grown with grass and clover species, making selective weed control challenging. One strategy to selectively remove tall weeds in pastures with mixed species is to apply herbicides using weed wipers. However, for many months of the year, plantain has upright leafless flower stems that will intercept herbicide applied using wipers. To determine if this means plantain might be damaged by wipers used in such swards, two glasshouse experiments tested the tolerance of mature plantain plants to the application of herbicides suitable for use in weed wipers (glyphosate, clopyralid, aminopyralid, dicamba, metsulfuron, picloram and triclopyr) to the flower stems. Aminopyralid (0.075% ai solution) and a low rate of glyphosate (1.8% ai) caused the least decrease in plantain biomass and should be safe for weed wiping within swards containing plantain. A higher rate of glyphosate (7.2% ai) and a glyphosate/metsulfuron mix (0.9% + 0.01% ai, respectively) caused the most damage to plantain, particularly following simulated rainfall after application. Thus, applying some herbicides using wipers should be possible for selective weed control within plantain swards even if rain falls soon afterwards, though field trials are required to fine-tune recommendations.