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Published online by Cambridge University Press: 07 February 2025
Basal bark application involves applying an oil-soluble herbicide in an oil carrier to the lower 0 to 45-cm of woody stems. For triclopyr, basal bark application typically requires the butoxyethyl ester formulation; however, this cannot be applied when standing water is present, which is common in seasonally flooded wetlands. Recently, the intermediate oil and water-soluble triclopyr acid formulation was registered for use in aquatic sites, allowing for basal bark applications in wetlands where standing water is present. Recent studies indicated that flooding after basal bark treatment can result in triclopyr release to surface waters and subsequent non-target injury. Elevated band application height (i.e., treating a higher band on each stem) may reduce non-target injury potential; however, this modified application technique has not been well tested on woody invasive species. To evaluate this approach, a field study on Schinus terebinthifolia was conducted near Melbourne and Wimauma, FL on well-established and juvenile rootstocks. Treatments included triclopyr acid at 17, 34, and 69 g L-1 applied in an oil carrier and treatment band heights of 0 to 45-cm and 61 to 107-cm from the ground line. At Melbourne, both band heights treated with 34 or 69 g L-1 resulted in 75 to 100% mortality of mature rootstocks. However, triclopyr applied at 17 g L-1 to the low and elevated band heights resulted in 70 and 11% mortality, respectively. All treatments resulted in 90 to 100% mortality at Wimauma, where the rootstocks were juvenile and much smaller. These findings indicate elevated band heights may be a useful approach for woody plant control and may support an effective management strategy in inundated wetlands that provides better prevention of non-target injury.