Salix euxina (I.V. Belyaeva 2009), Salix x fragilis [alba x euxina], Salix rubescens, Salix x rubescens

Environmental damage from S. fragilis invasion includes changes to stream hydrology, higher erosion and sedimentation rates and flooding patterns, and they may also use more water than indigenous plant species and cause changes to nutrient cycling, water temperature, energy fluxes and general water quality (Anon, 2000). There are negative consequences for biodiversity where S. fragilis becomes invasive, since the thick canopy created when it is dominant is sufficient to shade out other plants and reduce invertebrate abundance (Weber, 2003). These changes may also affect fish (Anon, 2000). Flora and fauna associated with both the banks and aquatic environment may be affected. Crack willow is susceptible to a variety of parasites and diseases; however, the degree to which it may serve as a vector for these into native willows is not known. Salix fragilis will hybridize with other willows, most notably with the nonindigenous white willow -- producing S. × rubens Schrank (Reznicek et al. 2011), but the degree to which this has affected native willows is unknown.

Salix fragilis has a moderate socioeconomic impact in the Great Lakes.
Salix fragilis can form dense thickets several meters thick, with densely-spaced stems (Cremer 1995, FEIS 2000) that could be major impediments to access waterways.  S. fragilis also has extensive roots, which can grow out into the stream, trapping silt and layering new roots over the top of the old ones and creating a broad shallow stream (Muyt, 2001) and blocking streams, drains and culverts (Webb, Sykes & Garnock-Jones, 1988).  As a semi-aquatic species, confined to stream banks or beds or moist locations, willows are unlikely to grow near enough to cause structural or visual damage to cultural sites.

Salix fragilis has a moderate beneficial impact in the Great Lakes.
S. fragilis is considered an important species in hedgerows, shelterbelts and windbreaks, along fields and field channels. It has also been planted to prevent soil erosion along streambanks. S. fragilis is not a timber species (wood density is about 450 kg/m³ at 15% moisture content) and has been mainly used for fuelwood. S. fragilis was once an important species for basket-making industries. (CABI 2014). Salix fragilis has been investigated for suitability for phytoremediation of metals. It may be suitable for remediation of sites contaminated with cadmium and zinc (Vandesasteele et al 2005).  It has also been investigated and has potential for phytoremediation of sulfonamide anitibiotics from confined feedlot livestock operations (Michelini et al 2012).

In 2011, the Great Lakes Indian Fish & Wildlife Commission ranked S. fragilis to be a low priority for regulation and control (Falck et al 2012). There are no known regulations for this species.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control

Biological
To our knowledge no research into possible biological control organisms for crack willows has been attempted in North America or anywhere else.  Candidates for insect control are generally not sufficiently specific to avoid damage to native willows.

Physical
Like most river trees, willows resprout vigorously from cut stumps, and will usually grow back into a tree eventually. Repeated cutting of new stump shoots can eventually kill the trees. But given their large root systems, cutting would presumably be needed to be done several times per growing season for several years in order to starve the roots. Mowing or weed-whipping might be useful for seedlings.  (GLIFWC 2013). Small seedlings can be hand-pulled, while larger trees may require a weed wrench or machinery to remove the root systems.   

Chemical
Given willows’ tendency to resprout from the roots, multiple applications will likely be needed for control.

The nonselective herbicide glyphosate (available commercially as "Roundup" and "Rodeo") is commonly used for treating woody invasives such as crack willows. Tryclopyr (Garlon 3A or equivalent amine formulation) is also effective against broadleaf and woody plants, and has the advantage of leaving grasses and sedges intact. Recently Roundup has been shown to be highly toxic to both adult frogs and toads and their tadpoles, probably due to the surfactant (polyethoxylated tallowamine, or POEA) in this glyphosate formulation (Relyea 2005). Because of this and other as yet unknown effects of various herbicide formulations on the environment, herbicide should be applied as precisely as possible and only when needed, using only the amount needed to get the job done.  Any attempt to control crack willows or other invasive plants in aquatic habitats must be done using Rodeo or other herbicides formulated for use over water. Permits are required for herbicide application over water in many states, including Wisconsin, Michigan and Minnesota.  (GLIFWC 2013).

Triclopyr amine is best used on young willows (seedlings) that are actively growing.  2,4-D LV ester  can be applied when leaves are fully developed and growing (amendable to aerial application).  Metsulfuron is used on fully leafed-out brush. 

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Salix × fragilis can be separated from S. euxina by having branches and branchlets hairy or glabrescent in age versus glabrous; leaf blades not glaucous abaxially versus glaucous; leaves amphistomatous versus hypostomatous or with stomata only along veins and at apex; and pistillate catkins slender and loosely flowered versus stout and moderately densely flowered.