A thorn in your side is a phrase we’ve all heard, and with locust species, it holds true. Honeylocust (Gleditsia triacanthos) is a deciduous, fast-growing, aggressive, thorny legume tree. The bark is grayish-brown and furrowed with long scaly ridges. The leaves are alternate, oval and 6 to 8 inches long. Black locust (Robinia pseudoacacia) is very similar in appearance but has dark brown and deeply furrowed bark. Both species produce white fragrant flowers that appear from May to June.
While honeylocust is more common, both species are found in pastures throughout most of the United States. Honeylocust spreads rapidly from seeds, outcompeting native vegetation and forming dense thickets of trees. Black locust reproduces rapidly by root suckering and stump sprouts, which can regrow to form groves of trees.
When cut, locust can produce abundant new sprouts from buds around the trunk and along the root system. Because of this, it’s important to kill the stump.
For basal cut-stump applications, prepare a mix of 25% PastureGard® HL herbicide or Remedy® Ultra herbicide plus 75% commercial basal oil. Spray the outer portion of the cut surface, the sides of the stump to the soil line and any exposed roots. You can use this same herbicide-plus-oil mix for low-volume basal applications to treat locust — and most other woody species — with trunks smaller than 6 inches diameter at the base of the tree.
You can make these treatments any time of the year, including winter months, as long as snow or standing water doesn’t prevent proper application. Late winter and early spring applications often provide optimum control. See the related article in this issue of Range & Pasture Steward for more information on low-volume basal and basal cut-stump treatments.
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