Many acres of Arkansas pastureland are infested with various bramble species, and their stubborn nature makes them difficult to remove, said Mark Keaton, Baxter County staff chair with the University of Arkansas Division of Agriculture.
“The presence of brambles is generally an indication of a neglected pasture,” he said. “They are seldom found in well-managed grazing land because they do not have an opportunity to become established.”
Blackberries, dewberries and raspberries are the most common bramble types.
Highbush blackberries (Rubus argutus) in particular have an unsavory reputation. They “probably are the most troublesome species in Arkansas.”
The blackberry plants are perennials that arise from roots, but the individual canes are biennial. Canes that produce flowers and fruits were vegetative the year before, said Keaton. After they produce berries in the second year, individual canes die and are replaced by new ones from the roots.
This constant renewal poses a thorny problem for Arkansas pastures.
Blackberry thickets have dense canopies, which discourage growth of pasture grass. Livestock avoid the plants due to their thorns. If the brambles are allowed to become established, the amount of usable grazing land is significantly reduced.
“Anyone who has mowed established blackberries for a few years knows that mowing will not get rid of them,” said Keaton. “In fact, mowing stimulates formation of new canes from lateral roots.”
Brush hogging can provide temporary relief, but not long-term control.
Herbicides, which kill brambles at the roots, may be the only way for effective control. The number of herbicides approved for use in pastures is limited, however. Using unregistered herbicides on grazing land is a violation of federal law.
Remedy, PastureGard and glyphosate are common pasture herbicides that will control blackberries well if used correctly, said Keaton. The recommended rate is three pints per acre — a 1 percent solution of Remedy or PastureGard or a 2 percent solution of glyphosate.
“Applying Remedy or PastureGard during or after bloom has been effective for blackberry and dewberry control,” he said.
Glyphosate should be applied in September. A surfactant should be applied to the spray mixture.
Do not treat blackberries in the same year after mowing, shredding or burning. “Even one year after removal of top growth, blackberry stands will be more difficult to control than undisturbed stands and will require treatment.”
Always remember to read and follow herbicide label directions. Herbicides should not be applied to drought-stressed plants.
“A follow-up spraying may be needed next spring to control those plants not killed by this application,” said Keaton. “If you use glyphosate, there is a 14-day grazing restriction for spot treatment. Also, grass in the treated spots will be killed by the glyphosate herbicide.”
Other pasture herbicides that control blackberries are Cimarron Plus, Surmount, Grazon P + D, Crossbow, Spike, Velpar, Weedmaster, Banvel and Tordon 22K.
For more information on controlling weeds in forages, see www.aragriculture.org/forage_pasture/Management_Guides/Forages_Self_Help_Guide9.htm, or contact your county Extension office.