Saturday, February 15, 2020

Deer Wars

Well maybe not full scale wars, but I need to find an acceptable balance where some new plants are allowed to survive to maturity.  The first battle was in creating a vegetable garden.  There using a double fence, two 4-5' tall fences about 4' apart, has been pretty effective at keeping the deer out.  Next was controlling deer browse on shrubs and new trees.  In those cases I have been having some success with repellent sprays, like Bobbex, and using wire cages around susceptible plants.  Plant selection is also important, by avoiding deer favorites like arborvitae and roses, I save a lot of heartbreak.

This pussy willow (Salix discolor) has survived repeated
deer 'rubs'.  The cambium layer has healed but left
the original heartwood exposed.  The short trunk guards
are not tall enough to protect all of the trunk
 susceptible to deer rubbing.
The next phase of the battle to wage is rutting season when the bucks look for the perfect tree or shrub to rub their antlers against to clear them of velvet, the outer layer that supports the growth of their antlers.  Here in the Mid-Atlantic rutting season begins around the end of October and runs for 1-2 months  The ideal targets for velvet removal are flexible saplings, 1-2" in diameter and over 2' tall.  Small evergreens seem to be a particular favorite.  This is bad news for the few Christmas trees that I am trying to grow.  I’ve lost a number of nicely shaped trees once they reach about 3 feet in height.  Trees with lots of stiff branches low down on the trunk are not as desirable.

I have a stiff 4' tall welded wire cage around this young sassafrass. 
This guards against deer browse but an aggressive buck
may be able to tear it loose.
I have been protecting the newly planted evergreens with chicken wire, which is good for a couple of years.  Once the trees get taller I had the bucks tear away the chicken wire.  Another problem with chicken wire cages is that they interfere with the shape of the tree. 

This year I tried a new technique that I heard about a number of years ago.  Lay chain-link fencing horizontally on the ground around the trees you want to protect.  The idea is that this creates an uneven surface on the ground that the deer find uncomfortable to walk on.  To be effective the fencing needs to be held a little bit above the ground level to create an unstable surface, particularly for hooved animals. It's kind of like a cattle guard. I was not able to get hold of any scraps of chain link, but it did salvage some 5 foot tall welded wire fencing to test this concept out.  The nice thing about the welded wire is that it is stiff enough that it can be held above the ground surface with fewer supports than chain link. 

The pink flags mark the corners of the horizontal fence.
I cut 6 foot long sections of the fence and cut a slit half way though in the middle to accommodate the tree trunk.  I turned the edges down so that once put on the ground the fencing would not lie flat, but would arch up a little.  The last week of October I laid out these horizontal fences around several small Christmas trees, a pussy willow (that had been damaged in the past) and a sweet bay magnolia (about 1.5” in diameter)

Here is a deer just skirting along the edge of the horizontal fence,
keeping a couple of feet away from the tree trunk.
It could probably lean in to munch on the branches if it needed to.

Results were mixed at best.  I didn't lose any Christmas trees (either with or without protection), but it did get some damage to other young trees despite having both the horizontal fence and a chicken wire cage.  Where it wasn't effective it may not have been raised enough off the ground or it may need a wider protection zone.  Another reason may be that it is just not very effective.  Advantages (if done right) are that it has a low low impact on appearance of the landscape (can't be seen from a distance) and it does not interfere with form of the tree or shrub.

This Douglas fir is getting some attention from a buck.  The tree is surrounded
by chicken wire but does not have the horizontal fencing.  This particular tree
has multiple trunks so it may not be a choice candidate for antler rubbing.

This 4" drain pipe was cut in a spiral using a hacksaw.
Note the ventilation holes.

I was very sad that the deer attacked my magnolia.  It had finally gotten tall enough that the leaves were out of reach of the browsing deer.  For single-trunked trees some sort of bark protection may be the best route.  You can buy these like the spiral wound tape, plastic mesh, tubes.  Also chicken wire, hardware cloth or welded wire fencing can be wrapped around the trunk.  Alternatively you can make them from flexible drainage pipe.  One concern with this black pipe is heat build-up in the pipe during the winter.  To reduce this I drilled ¾” holes every 6 inches to let in air.  It would be better to use white-colored piping (does that even exist?).   You need to be careful not to damage the bark when putting rigid tubing around a tree.  Another feature of the  plastic pipe is that it makes the trunk appear larger than the 1-2" diameter that the bucks prefer.

 Bugs can also hide out under the protective pipe or wraps.  So you need to watch out for that.  This year I put truck protectors on too late, after the damage was done.  But I went ahead and put them on anyway, just in case a buck came back to finish the job.  For the spring and summer I will remove the tubes so that the trunk can heal and develop naturally.  I will just need to remember to put them back on in early fall.  

Here's my sweetbay magnolia with the  protective tube in place. 
The arrow indicates how high up the deer damage went
 before the tube was put on.  The antler rubbing happened despite having
 both the horizontal fence and a 3' tall chicken wire cage.

I also tried wrapping some plastic mesh fencing around some trees.  This was easier to do but I’m not sure if it will offer as much protection as a solid tube (better than nothing?)

This plastic fencing was very easy to put around the tree. 
Heat build up is not an issue, but I'm not sure how much
 protection it will really offer.

So, in review, for single-trunked trees a trunk wrap or protector of some sort should do the job.  For trees and shrubs with low branches, a perimeter cage, well anchored to the ground, should do the job.  The horizontal fencing as described here still needs some fine tuning but holds some promise since it does not interfere with the growth of the plant and it has a low visual impact.