Ever wonder the effectiveness of herbicides on honey mesquite during drought? Well, researchers from our department were wondering the same thing and studied how drought effects herbicide efficacy in herbaceous and woody plants. There were chamber studies conducted to evaluate the influence of water stress and triclopyr on the absorption and translocation of clopyralid in greenhouse-grown honey mesquite. Clopyralid is an auxin-type herbicide highly effective at honey mesquite control. It is often used alone or in combinations with other active ingredients to form common honey mesquite foliar-applied herbicides like Sonora™ and Sendero™.
Drought did not affect absorption or translocation of clopyralid alone. With 1.5-month old honey mesquite, the addition of triclopyr to clopyralid increased clopyralid absorption in leaves at low to medium water stress, but did not affect translation at 4-hours following herbicide application. On 3-month old honey mesquite, triclopyr decreased clopyralid translocation 24-hours following herbicide application at high water stress.
Droughts do not impact Clopyralid absorption and translocation into honey mesquite plants when evaluated 4 or 24 hours after treatment. The data indicated that rapid translocation of Clopyralid was detected within 4 hours and that 63-77% of the original amount of Clopyralid remained in the plant tissue.
Through this work, it is evident that Clopyralid is highly mobile and stable within honey mesquite! However, reduced uptake of Clopyralid occurred when applied with triclopyr during high water stress.
For more information, be sure to check out the full study – Water stress and triclopyr on clopyralid efficacy in honey mesquite!
Roche, Andrea R., et al. “Water stress and triclopr on clopyralid efficacy in honey mesquite.” Journal of Range Management, 55:266-269, (May 2002.)