European Alder (Alnus glutinosa)

Invader Type: 


Mechanical Control: 

Hand pull: Any time of year when the ground is soft, especially after a rain, hand pull small plants by the base of the stem. Be sure to pull up the entire root system. Hang plant from a branch to  prevent re-rooting. For larger plants, use a Weed Wrenchâ„¢. Continue to monitor the area every year for new seedlings.

Cut stump: Repeated pruning of established plants to ground level without subsequent herbicide application is not effective for European Alder control. Each regrowth results in a thicker stem base and denser branches.


Chemical Control: 

CAUTION: Because this plant grows in and close to wetlands, aquatic herbicide formulations must be used.

Cut stump: Cut the plant 4 inches above the ground. Use a drip bottle to apply a 18-21% glyphosate solution to the stump within one hour of cutting. This is best done in late summer through winter when plants are transporting resources to their root systems.

Low volume foliar spray:  This method is used for dense populations and best left to a contractor. During the summer months, July to August, spray a 2% glyphosate solution on the entire leaf surface of the plant. In order to avoid drift to native plants, spray only on calm days.




Pest Overview and Identification: 

DESCRIPTION: Alnus glutinosa is a rapidly growing tree that can reach 20 m (65 ft.) in height. The tree often has a multi-stemmed trunk. The bark is smooth and dark brown. With age, the bark can show some shallow fissures. The leathery leaves are obovate to nearly orbicular in shape and are 3-9 cm (1-3.5 in.) long and 3-8 cm (1-3 in.) wide. The leaf bases are rounded to broadly cuneate and the margins of the leaves are coarsely or irregularly doubly serrate. The teeth can be acute to obtuse or nearly rounded. The upper leaf surface is glabrous, while the veins of the leaf on the lower surface are pubescent. The young leaves are coated in resin. The leaves of this plant persist late into the fall. (SOURCE: The identification information on this species is taken from the Invasive Plant Atlas of New England (IPANE) website at Modifications include additional pictures ( resource information. Check the website links for future updates.)

Reproductive Strategy / Lifecycle: 

European alder commonly sprouts from the stump after cutting, and live branches can be layered successfully. European Alder (Alnus glutinosa) is a nitrogen-fixing plant that has the ability to become established on very poor soils.  Average number of seeds per tree is 240,000  



Ecological Threat: 

Its ability to be dispersed by water andform mono-specific stands, makes it a threat to native wetland species