“Big weed trees” are uninvited, rapidly growing trees that can disrupt a cultivated landscape. These trees are not intentionally planted and often establish themselves through natural dispersal, becoming problematic intruders in gardens and other areas. Their presence can detract from the intended aesthetic and health of a landscape.
What are Big Weed Trees
Big weed trees are characterized by their aggressive growth habits and ability to quickly establish themselves in various environments. They exhibit rapid growth rates, often reaching significant heights and widths in a short period. Many species also produce abundant seeds that readily disperse, leading to widespread self-seeding. Another common trait is their capacity for vegetative reproduction, sprouting new trees from their root systems or cut stumps.
These trees pose several challenges for homeowners and the environment. They outcompete desirable plants for resources such as sunlight, water, and nutrients, reducing biodiversity in an area. Their extensive root systems can cause structural damage to foundations, sidewalks, and underground utilities. Their unchecked growth can block views, create dense thickets, and diminish the overall aesthetic appeal of a property. Many are non-native and invasive, lacking natural predators or diseases in their new environments, allowing them to spread aggressively and negatively impact local ecosystems.
Common Big Weed Tree Species
Identifying specific big weed tree species is the first step in effective management. Three common examples often encountered are Tree of Heaven, Empress Tree, and Black Locust, each with distinct features.
Tree of Heaven
Tree of Heaven (Ailanthus altissima) is a fast-growing, deciduous tree native to China. Its leaves are large, pinnately compound, ranging from 1 to 4 feet long, with 10 to 40 lance-shaped leaflets. A distinguishing characteristic is the presence of one or two glandular teeth at the base of each leaflet. When crushed, the leaves or twigs emit a strong, unpleasant odor. Mature bark is light gray and smooth, developing shallow fissures with age, and female trees produce abundant clusters of winged seeds, 1 to 2 inches long, which turn yellow to reddish-brown as they mature.
Empress Tree
Empress Tree (Paulownia tomentosa), also known as Princess Tree, is another rapidly growing deciduous species native to China. This tree is recognized by its very large, heart-shaped leaves, 8 to 12 inches long, which have a velvety, fuzzy texture on both sides. In spring, before the leaves fully emerge, it produces showy, trumpet-shaped, fragrant lavender flowers in upright clusters. These flowers are followed by distinctive oval-shaped, woody fruit capsules, 1 to 2 inches long, that mature to brown and contain numerous tiny, winged seeds. The bark is thin and grayish-brown with shallow fissures.
Black Locust
Black Locust (Robinia pseudoacacia) is a deciduous tree native to the southeastern United States but has naturalized widely. Its leaves are pinnately compound, featuring 7 to 21 oval to round leaflets, arranged alternately along a central stem. A notable identification marker is the presence of small, stout, curved spines, typically in pairs, at each leaf node on the branches. In late spring to early summer, it produces fragrant, drooping clusters of white, pea-like flowers. These flowers develop into flat, smooth, papery pods, 2 to 4 inches long, containing small, dark-brown seeds, and mature bark is dark gray-brown with deep furrows.
Effective Removal and Management
Removing big weed trees requires a strategic approach, considering both mechanical and chemical methods to prevent regrowth. For young seedlings and saplings, manual removal is effective. Small trees can be pulled by hand, ensuring the entire root system is extracted to prevent resprouting. A weed wrench can assist in pulling out small stems and their roots.
For larger trees, mechanical methods include cutting and girdling. Cutting the tree down at ground level is a primary step, but it is often followed by vigorous stump and root suckering. Girdling involves removing a complete band of bark and the underlying phloem and cambium layers around the circumference of the trunk, down to the sapwood. This interrupts the flow of nutrients from the leaves to the roots, eventually killing the tree.
Chemical treatments are necessary for mature trees to ensure complete eradication and prevent regrowth. Stump treatment with herbicides is a common and effective method. After cutting down the tree, an appropriate herbicide is applied directly to the freshly cut stump surface, particularly to the outer cambium layer. This application should occur within minutes of cutting to ensure maximum absorption before the cut surface dries and seals.
Basal bark application is another chemical method suitable for smaller trees. This involves spraying a mixture of herbicide and oil carrier to the lower 12 to 18 inches of the tree’s trunk, saturating the bark all around. This method allows the herbicide to penetrate the bark and be translocated throughout the tree, including the roots. Late fall and winter are optimal times for both stump and basal bark applications, as trees transport carbohydrates to their root systems, enhancing herbicide translocation and reducing sap flow. Always follow herbicide label directions for mixing ratios and safety precautions, including wearing appropriate protective gear, and for very large or hazardous trees, consulting a professional arborist is recommended to ensure safe and effective removal.
After Tree Removal
Once a big weed tree has been removed, proper management of the site is important to prevent future issues. Disposal of tree debris should follow local regulations, which may include chipping, composting, or hauling away larger sections. This helps to clear the area and can provide useful mulch.
Continuous monitoring of the area is necessary for new sprouts or seedlings. Big weed trees, especially those that reproduce from root suckers, can send up new growth even after the main trunk is gone. Promptly removing these sprouts manually or treating them with a targeted herbicide prevents them from re-establishing.
Replanting the area with desirable, non-invasive, or native species is an effective long-term strategy. Native plants are adapted to the local environment and can help restore ecological balance, making the area less susceptible to future invasions. This proactive approach helps to fill the void left by the removed tree, ensuring a healthier landscape.