Chinese privet is one of the most invasive shrubs in the southeastern United States - frequently growing in dense thickets along roadsides, on rights of way and in forests. Now the journal Invasive Plant Science and Management has good news for land managers battling the shrub. Researchers say you can achieve great control with much less herbicide than typically used.
A team of scientists investigated a popular "cut and treat" technique that involves removing Chinese privet's dense foliage and applying glyphosate or triclopyr to control new shoots emerging from the root collar. During a multiyear study at two forested sites in Alabama, varying rates of glyphosate and triclopyr were applied to Chinese privet root stumps in the spring and in the fall to evaluate their relative effectiveness.
The study showed that Chinese privet was well controlled when the herbicides were applied at a 25 percent concentration—significantly less than the 50 to 100 percent concentration recommended by the product labels. Researchers also found that timing matters. They documented a slight increase in the recovery of lateral root sprouts following spring triclopyr treatments. As a result, fall treatments are recommended.
"Our research shows that land managers can make significant reductions in the amount of herbicide used to treat Chinese privet, while still optimizing control," says Stephen Enloe, associate professor at the University of Florida. "With further research, it may be possible to reduce application rates even further based on stem size and the active ingredients used."
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Stephen F. Enloe et al, The Influence of Treatment Timing and Shrub Size on Chinese Privet (Ligustrum sinense) Control with Cut Stump Herbicide Treatments in the Southeastern United States, Invasive Plant Science and Management (2018). DOI: 10.1017/inp.2018.3