Boxelder (Acer negundo)

DESCRIPTIONS
Boxelder: This tree can grow to 65 feet. Leaves are pinnately compound and have 3-5 leaflets arranged oppositely on the stem. The leaflets can be lanceolate to oblong, with margins that may be separated into several shallow lobes. Boxelder is dioecious: the "male" plants bear stamens in umbel-like arrangements, while the "females" produce apetalous flowers in racemes. The fruits produced by the female plants are double samaras, or winged capsules composed of two easily-separable lobes.

DISTRIBUTION AND HABITAT
Boxelder: Boxelder is an opportunistic species native to the United States. Its range encompasses most of the continental U.S., from Florida north to New Hampshire and west to the Pacific Ocean. Preferring moist, alluvial soil, the tree usually grows along river banks and on the flood plains of streams. Extremely prolific, it will inhabit many environments disturbed by humans, including abandoned roads and railroad beds, deserted gravel pits, the peripheries of dumps, and areas around fences and buildings. It is common in rural yards, and its presence is often associated with past or present human occupation of an area.

LIFE HISTORY AND EFFECTS OF INVASION
Boxelder: Boxelders bloom between March and May, depending on region. The flowers produce samaras during summer and fall, and the wind disperses the fruits to suitable habitats for germination. Reproduction can also take place vegetatively through suckers, sprouts, and root shoots. Boxelders are aggressively opportunistic and tend to shade out smaller, herbaceous flora in wetlands and other areas.

CONTROLLING WILLOW, COTTONWOOD, BOXELDER, AND DOGWOOD
When choosing a control strategy for willow, cottonwood, boxelder, or dogwood, it is important that the habitat manager carefully observe the life-history responses of the trees or shrubs within the target region, because responses may vary from region to region, affecting the success of management manipulations. For instance, in northerly regions, willow can be controlled by mowing seedlings and saplings and subsequent flooding; farther south, mowing and flooding may actually induce more aggressive plant growth.

Mechanical Methods: The complete drawdown of water in an impoundment during the hottest summer days may prevent the establishment of extensive root systems by woody plant seedlings. Combined with discing, drawdown can terminate newly established seedlings and destroy the root systems of older plants. It should be noted that in southern latitudes, woody species of plants may experience an enhanced germination rate if drawdowns expose great expanses of mud flats before seed dispersal; exposing mud flats after seed dispersal can reduce and confine establishment of woody plant growth.

Discing is an economical technique that can destroy both aerial and subterranean woody plant growth. A double cross-disc is most effective for disturbing especially dense stands of trees and shrubs. Discing 2-3 times during the growing season is the best method to impair seedling growth. Discing becomes ineffective when plant stems reach more than three inches in diameter. After plants reach four inches in diameter, bulldozing is the only feasible method to physically remove them from the landscape en masse. The method is rarely advised due to the obvious resulting alteration of wetland topography.

Cottonwood can be eradicated through girdling. Boxelder, however, is resistant to girdling and sends up multiple shoots below the point where its phloem is severed. Large-diameter trees can be removed with a chainsaw. Resprouts must be recut, or herbicides may be applied to the cut stump (see below).

Chemical Control: Because new shoots may sprout from severed trunks, cut stems and stumps must be treated with an herbicide, such as glyphosate licensed for use in wetland environments.

Glyphosate applied to foliage at 7pts/acre in August has been found to kill dogwood and willow, although this herbicide will harm most anything green. Notice must be posted before spraying due to possible fish contamination. Hand-held or tractor-mounted wick applicators can be very effective in the application of foliar herbicides to relatively low dogwood and willow stems.

Grey dogwood can be successfully controlled by cutting stems in summer and fall, and then carefully applying an herbicide to cut stems using a spot applicator. Basal bark application may also be effective.  

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