Salix purpurea var. nana Dieck, Salix purpurea f. gracilis (Gren. & Godr.) C.K. Schneid., Basket willow; Purple osier willow

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Beneficial

Salix purpurea is susceptible to numerous diseases and parasites, but the degree to which it acts as a vector for these into native willows is unknown. This species will hybridize with other willows, but the degree to which this effects willows native to the Great Lakes region is unknown. It stabilizes banks, but can disturb sand dune ecosystems in Michigan (Reid and Holland 1997). Willows in general have the ability to produce dense stands in floodplains and other favorable habitats (GLIFWC 2013). Changes in the composition of insects and other aquatic invertebrates were associated with the presence of these willows, as well as increased water temperatures (GLIFWC 2013), but it is not certain whether this effect is specific to the invasive or would be the same for any native riparian tree.

There is little or no evidence to support that Salix purpurea has significant socio-economic impacts in the Great Lakes.

No socioeconomic impacts have been specifically documented for this species.

Salix purpurea has a moderate beneficial impact in the Great Lakes.
Realized: 

This species is commonly planted for erosion control and bank stabilization and is commonly used for basket-making (Reznicek et al. 2011), but native willows are available that would function similarly. Salix purpurea provides cover for small animals and browse for deer, beaver and rabbits, as well as exceptional nesting sites for birds.

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

Control
Cultivars of S. purpurea are often used for erosion control and most species-specific management information stems from this use.

Biological
To our knowledge, no research into possible biological control organisms for 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.

Gypsy moths can defoliate purple willow and willow midges can cause significant (though rarely fatal) damage. Willow blight is a serious pest to plantings, particularly plants that have been damaged by storms. Beaver can have huge impact on this species and are capable of eradicating entire stands (USDA NRCS 2002).

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.