Thursday, July 10, 2014

Invasive Plant: Buckthorn identification and control

Common Buckthorn Hedge  
Buckthorn trees are taking over the woodlands and hedges around my neighborhood, my town, my state and the country. Darn invasive species are so good at that. 

While some people love what a robust hedge Buckthorn can make. I hate them and enjoy ripping them out. Many states and towns have designated Buckthorn as a restricted, noxious weed. My town has an active free removal process and will haul away any Buckthorn cut down.  For me clearing out buckthorn is an effort worth undertaking. I love seeing a nice forest with Oaks and other native plants. 

Why remove Buckthorn trees?  I'm taking them out to restore a woodland area.  I've posted a few blogs on my woodland restoration.  Some of the pictures here are from that process. But long before I started that restoration effort I had challenges removing Buckthorn from my yard. They were creeping in at the corners, under the phone lines, along the house line all the places that nothing else wanted to grow - these little beasts were thriving! I never liked how they looked as trees. So many other great options. 
Buckthorn crowding the woodland

Here are some reasons why you might consider removing buckthorn too:
  1. Buckthorn squeezes out native plants for nutrients, sunlight, and moisture. These invasive trees choke out surrounding vegetation including other trees and makes it impossible for any new growth to take root under its cancerous canopy of dense vegetation. They leaf out earlier in the spring that anything else and they hold onto their leaves longer in the fall. That means less light and water for everything around it. 
  2. Buckthorn degrades wildlife habitats and disrupts food chains. It removes food sources and shelter plants.  No nice flowering plants in this thicket of buckthorn - just poison ivy and garlic mustard :(
  3. Buckthorn is super invasive - there aren't the natural controls that would curb its growth here in USA. One Buckthorn becomes 100 and the woodland or forest can become saturated with just these trees. Buckthorn is shade tolerant and can grow in poor soils even wet areas. It loves to creep in where no other plant wants to go.  The tree has both male and female parts so one tree can create hundreds of seeds. seeds which last for year in the soil, and birds eat and spread. Damn Buckthorn.
  4. Buckthorn contributes to erosion by overshadowing plants that grow on the forest floor, causing them to die and causing the soil to lose the integrity and structure created by such plants.
  5. They are not valuable contributors to the landscape from a water management of property value perspective. Check out this link to see the value of trees you may have in your yard. 
Common Buckthorn;
Photo: www.illinoiswildflowers.info
Is it a Buckthorn? There are two basic kinds - common (European)  and glossy (alder) buckthorn.  I have hundreds of common buckthorn.  Common Buckthorn grow in a shrub habit with several stems (potentially) originating from one trunk (or ground.) They can reach 20-25 feet in height and may form dense thickets. Hence the popularity as a hedge plant by my neighbors :(   The leaves are oval with fine toothed edge, dark green and dull. They have 3-5 pair curved leaf veins.  It's easy to spot these trees in the spring - the first to leaf out, or the fall - that last to stay green. Buds are opposite each other and let's not forget the thorn at tip of the twig. The round fruit is greenish black and small, 1/4" round in clusters.

Here are some close up shots of buckthorn tree clumps, and regrowth from previously cut buckthorn from the restoration effort. 


Small Buckthorn, Note More growth at base
of three in back left.


Clump forming growth Buckthorn













OK - so how hard is it to get rid of Buckthorn? VERY HARD! Buckthorn have very extensive root systems. This helps them grab all the water and makes the trees difficult to remove. The roots can stay dormant in the soil for long periods of time - so just cutting the tree at the surface will only result in re-sprouting growth with much more vigor. The seeds are viable for 5-7 years in the soil. So when you kill a bunch of buckthorn, sunlight comes into the area and awakens the seeds. So its essentially a never ending battle for me in the woodland restoration. Seeds will continually be laid down from birds and nearly yards. However, progress can be made and maintaining once trees are removed is manageable.  In most cases some form of burn or chemical treatment will be needed to keep buckthorn away long term. 

Here are some tips for Buckthorn removal

  • PULL IT: If the buckthorn plants are small (diameter less than a pencil) This works really well is the ground is moist/saturated. 
  • SPRAY IT: If it's small you can just use herbicide treatment. I use glyphosate herbicide - Roundup ‘poison ivy killer’ and completely soak the leaves, care not to get on adjacent plants. 
  • CUT-STUMP METHOD:  If the buckthorn is large diameter cut the tree off, leaving 3-4 inches of the trunk. (Hence the stump.)  Use a paint brush to apply glyphosate concentrate to the stump.  Get it completely wet and do not skimp. Here is use the Roundup Poison Ivy Concentrate.  Bored in the wintertime and nothing to do in your garden? Don't worry, you can still kill buckthorn. Yup - the cut-stump method even works in the wintertime! 
  • BARK PAINTING: Take the concentrated herbicide and paint it right onto the bark (Basal Bark or Basal stem treatment) Really get it saturated. May need a few applications, but eventually the tree will die and then it can be cut down at ground level (no stumps to trip over.)
  • FIRE; Controlled burn will remove the trees and seeds
  • GOATS: I hear they love eating buckthorn and can clear are area fairly quickly. They will eat everything - so block off and guard keepers.  This goat-eating treatment needs to be repeated several times a year for several years. Seed management also needed.
A more comprehensive list of techniques and pros/cons of each can be found on Prairie Enthusiasts website.  If you can't get the trees removed completely - cut them down to within 6 inches of the ground in June time frame. This prevents them from putting out any new seeds that year. 

Removing buckthorn nearly every weekend - I have my toolkit always at the ready. This includes gloves, Garden Hedge Trimmers (hand clippers), 24" bypass loper, Sawzall, Round-up  spray and Roundup/brush carry combo.  My improvised combo set is a cut off plastic pickle jar duct-taped to the roundup container - I keep the treatment brush in the plastic container. This keeps the brush always handy and prevents a soaked brush falling onto other desirable plants.  

Removing buckthorn is a labor intensive and will be effective when done systematically and methodically, year after year after year. But then the fun begins in designing and planning for replacing those wicked damn buckthorn with something new.  I've put in lilac, dogwood, evergreens, river birch, and also just let nature take it's course. That is except for buckthorn regrowth from those nasty seeds ;)

Have a great day!

Teresa Marie