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Control weeds around hardwood seedlings
GRENADA, Miss. -- Growth and survival of planted hardwood seedlings are not guaranteed, and forest managers may need to learn more about establishment methods to avoid failed plantings.
Several factors can decrease seedling survival and growth, including soil conditions, planting techniques, seedling quality and competing vegetation. Survival and growth are improved if you properly plant high-quality seedlings and apply best forestry practices. Notably, control of herbaceous, or nonwoody, weeds can improve seedling establishment.
Competition from leafy vegetation is a major factor in hardwood plantation failures. Both herbaceous and woody plants may threaten the survival of hardwood seedlings. Herbaceous weeds pose the greatest threat during the first years of establishment. Competition robs seedlings of soil moisture and nutrients.
Herbicides commonly used in site preparation can provide excellent control of competing vegetation. However, many hardwoods are susceptible to most of these chemicals, so they are applied well ahead of planting. This timing often results in a short-term solution that does not adequately control competing plants throughout the growing season. Seeds of highly competitive weeds on or near the soil surface can grow and overwhelm seedlings after the herbicides degrade.
Providing longer term vegetation control during the growing season typically requires special efforts to improve hardwood seedling survival. When seedlings are treated with certain herbicides, growth and survival are enhanced.
Products containing sulfometuron methyl, oxyfluorfen or imazaquin, and other herbicides have been used successfully. In Mississippi alone, several hardwood species have benefited from herbicide weed control after planting: black walnut, sweetgum, persimmon, red and silver maple, bald cypress, winged elm, sugarberry, honey locust, black locust, American sycamore, box elder, cottonwood, green and white ash, and at least 13 species of oak. Greater growth and survival were the main benefits.
When choosing which chemical is most appropriate, consider proper application rates and timing, as well as susceptibility of both the seedlings and the weeds. The current standard broad-spectrum herbicide for hardwoods is sulfometuron methyl applied at 2 ounces per sprayed acre. Use both broadcast and banded applications for either total leafy weed control or wider vegetative diversity in wildlife efforts.
Consult an Extension employee, a forestry consultant or professional herbicide applicator for the appropriate chemical for any particular treatment. Additionally, strictly follow all label restrictions and recommendations when using any herbicide.
Editor’s Note: Extension Outdoors is a column authored by several different experts in the Mississippi State University Extension Service.