Robinia pseudoacacia L. (black locust) is recognized as a global invader due to its ability to colonise areas quickly, produce lots of seeds, and produce suckers when disturbed. It’s ability to fix nitrogen in the soil allows Robinia to spread into low quality soils, once used to reclaim disturbed sites, the plant is now recognized as a weed on most continents. Many gardeners plant Robinia species because of their golden appearance and large colourful flowers, however these species are grafted onto black locust root stock which produce thorny suckers when the roots are disturbed. These suckers can even pop up into neighboring yards 15m away causing disputes, some of which has led to civil action.
Don Burke, of Burke’s Backyard, lists the global invader Robinia as one of the trees gardeners will regret they planted!
Robinia suckers can pop up vigorously after soil disturbance with sharp thorns that can make removal even harder.
The Ask Sabrina section of The Weekend West advised that a concoction of 200ml of blackberry and tree killer mixed with one teaspoon of kerosene painted on to the cut sucker immediately, is very effective. Hard-to-kill plants such as oleander and tree of heaven are also susceptible.
Website Herbiguide give this control advice “Cut down the tree and paint the stump with neat glyphosate to reduce regrowth and suckering. Spray regrowth and suckers when they are about 500 mm tall with glyphosate. It re grows vigorously from cut roots and stumps and these sprouts need to be removed continually to exhaust the root system. Access, Grazon and metsulfuron are worth a trial.”
The Meat and Livestock Association of Australia rates Robinia as moderately palatable for goats in their handbook titled Weed control using goats- a guide to using goats for weed control in pastures. Giving a chemical free option for weed control.
According to some the black locust has some health benefits and parts of the tree can be used for different therapeutic uses. Infusions can help burning in the stomach, and with fatigue and nervousness. The flowers can apparently help with wounds and burns- this could be helpful after attempting the removal of thorny suckers.