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A major threat to Wisconsin’s forests

Hello Kretz Forest Family and Friends:

It was my turn to come up with an article for the newsletter, so I decided to address a very big concern of mine and one that should concern all who strive to keep our forest healthy: the major threats of invasive species, especially buckthorn and garlic mustard.

These two invasive plants have caused major problems for forest landowners by displacing native understory vegetation, forming an impenetrable understory layer, destroying wildlife habitat and causing long term decline of forests by shading out other woody and herbaceous plants. 

There are two kinds of buckthorn, glossy and smooth. They both leaf out very early in spring and retain their leaves late into autumn. Leaves are dark green and do not change color before being shed in the fall. Common buckthorn fruits are green, changing to black in the fall, and eaten by birds and mammals, yet poisonous to humans. 

(Photo by UW-Extension)

How did these get here and how do they spread?

Buckthorn was introduced into North America as ornamentals, planted as hedgerows and shelter belts during the 1800s. 

Buckthorn invades woodlands, savannas, prairies, abandoned fields, marshes, wetlands and roadsides, capable of growing in full sun and dense shade. They are fast growing woody perennials and if not controlled they can and will spread quickly. Forest understories can become so dense that native species of wild flowers and woody regeneration cannot compete and eventually disappear. 

What can you do?

Control of buckthorn is best achieved with early and frequent identification and removal of isolated plants before they begin to produce fruit. Established stems will need to be cut and chemically treated. Herbicide treatments are Glyphosate (Round-up), Triclopyr  (Garlon 4) and 2,4-D, which provide excellent control when used properly.        

In general, the best time to treat buckthorn is in the mid to late autumn. This plant retains its leaves much later into the fall than other plants. There are three common methods for applying herbicides: cut stump, basal bark, and foliar sprays. 

Both buckthorn and garlic mustard have drastically dictated how we manage our forests.  Garlic mustard, for instance, had made summer logging unacceptable due to spread of seed.  Dollars must be set aside to combat these invasive species or we lose our forests.

Educate your neighbors of the drastic effects of invasive species.  I cannot stress the importance of early detection and treatment. For more information, see your local department of natural resources. 

This is a long term battle which must be fought yearly.  Good Luck!

Dennis Fincher
Forester, Kretz Lumber Company

Have questions or want assistance in determining the best forestry strategies for your land? Contact our forestry services team or call Dennis at 800-352-1438. We can help you design plans that meet your goals and have the best interest of your forest in mind.

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