The leaflets are 2 to 4 inches long and they will change to a yellow-green color in autumn, typically before any of the other maples do in Indiana. Boxelder leaves can have as many as nine separate smaller leaflets on a central stem, which composes the compound leaf. The leaves will fool you into thinking it may be some type of ash tree, states the Floridata website, since they are compound and not simple leaves like most maples possess in North America. Maintenance: Follow-up treatments will be required, as seeds already present in the soil will sprout.Boxelder (Acer negundo) is a medium-sized maple species that grows to between 30 and 60 feet tall. Contact the Office of Indiana State Chemist (OISC) for additional pesticide use requirements, restrictions or recommendations. IMPORTANT : The pesticide label is the law! When using any chemical control, always read the entire pesticide label carefully, follow all mixing and application instructions and use all personal protective gear and clothing specified. Because this method involves applying herbicide mix to foliage (leaves), it should be considered for small dense infestations only.
Foliar application can be effective as well, using glyphosate at a 2% dilution. Cut stump method is also effective with glyphosate at a 20% dilution. Cutting and girdling are effective for trees of any size when cut surfaces are treated with herbicide such as glyphosate. Basal bark treatment is effective for trees less than 4 inches in diameter, using triclopyr at a 20% dilution. Because Norway maple produces dense stands, removal of all trees may alter site conditions by opening up the site so care must be taken to watch for and remove seedlings from Norway maple as well as other invasives that may move in.Ĭhemical: Norway maple can be effectively controlled using any of several readily available general use herbicides such as glyphosate or triclopyr. Mechanical: Removal of overstory trees as well as of understory seedlings and saplings is necessary to reduce seed sources. Hand pull seedlings in spring while soil is moist. Manual: Can be effective for single plants or very small infestations. Return to remove seedlings and other invasive species that may move in. Remove large seed-producing trees and pull, dig, cut, and/or treat with herbicide.
It also releases toxins that reduce the growth and reproduction of native species. It reproduces rapidly with heavy seed crops every 1-3 years.ĮCOLOGICAL THREAT: When Norway maple escapes cultivation and invades natural areas it reduces species richness and native tree regeneration by out-competing other trees and understory species for resources, creating dense shade canopies, and spreading rapidly through high seed production. It can be found on roadsides, degraded areas, hedgerows, roadside thickets, disturbed and intact forest communities, and is somewhat resistant to drought. HABITAT & DISTRIBUTION: Norway maple prefers full sun and fertile, moist, well-drained soils, but is shade tolerant and occurs in a variety of soil and moisture conditions. Norway maples will retain their leaves longer than other maple species in the fall. The paired samaras of Norway Maple form nearly a 180 degree angle, while those of Sugar Maple are less divergent, forming a 90 degree angle approximately. Norway maple can be distinguished by a milky white sap that exudes from the leaf petioles when broken (during spring, summer, and early fall), broad leaves, hair-like leaf tips, and bright yellow fall foliage. LOOK-A-LIKES: Norway maple looks similar to sugar maple ( Acer saccharum) and red maple ( Acer rubrum), both native species to Indiana. As with other maple species, seeds are dispersed by wind. The pendulous fruit (samaras) are 1.5-2 in long and samara wings are divergent, reaching nearly 180-degree angles to each other. 25 in wide, appear in April and May, and are yellow-green in color. The slender stalks of each corymb are green and either hairless or glandular-hairy. Both types of flowers are produced in umbel-like clusters spanning 2-3" across each cluster consists of 10-30 flowers. Norway Maple can be monoecious or dioecious, producing male (staminate) flowers and female (pistillate) flowers on either the same or separate trees.
The bark of the mature Norway maple has a very regularly ridged pattern similar to white ash, while on younger trees the pattern is more diamond shaped. wide and usually green in color, but there are a few cultivated species that are red. Palmately lobed leaves are opposite and have 5 to 7 sharply acuminate lobes (with large but few teeth). IDENTIFICATION & BIOLOGY: Norway maple is a broad deciduous tree, typically growing 40-60 ft but can reach up to 100 ft.