Don't be STUBborn

For decades we've known when pruning the final cut should be at, or just outside, the branch collar.  When trees shed branches naturally it's at this point. This is where the tree has the easiest time compartmentalizing and growing over the wound.

Now, it seems there's been some debate over the past few years about what to do when pruning larger branches back to parent stems on mature trees.  Some seasoned arborists have insisted that leaving a stub is prudent when dealing with large branches.  The idea is that by leaving a stub, decay will be slowed when moving into the stem.  

What needs to be considered though, is in a short period of time the vascular system around this stub is going to die.  This means any physiological process the tree has to fend off decay will cease, creating a corridor for decay to enter the parent stem through both heartwood rots and sapwood rots.

Below is a picture of a willow oak damaged in a storm 3 or 4 years ago.  During the storm a large branch broke out leaving a substantial stub.  In that time I've driven past this tree almost every day.  A few weeks ago I noticed bark separating from the underside of the damaged limb.  When I got out to look, it was obvious that sapwood decay had moved from the dead stub into the parent branch.  Had a proper cut been made the tree would have had a better chance of reacting to the damage.  Sure, decay still may have moved in to the stem, but the tree would have been putting on reaction wood to close the wound and reinforce the structural wood around the damage.

The red arrow shows where decay has moved from the damaged stub into the parent branch.  You can also see wound wood forming around the decay.  This has become a large area to heal over vs. if a proper cut was made at the branch collar.

It's Phytoplasmatic

Phytoplasma are specialized bacteria-like organisms that are obligate parasites of phloem tissue, and they can do strange things to plants.  Phytoplasma can cause leaf yellowing/variegation, twig distortion, witches brooms, etc.  They are spread by insects, like leaf hoppers, from infected plants to new hosts. 

In most instances infection by phytoplasma is not big deal, but in the case of a few diseases, namely; elm yellows, ash yellows, lilac witch’s broom, and grapevine yellows it can be deadly.  The best control method of phytoplasma is the removal, and offsite disposal of affected plant material.  Insecticide treatments to control the vectors may be helpful as well.

Diagnoses of phytoplasma can be difficult.  Viruses, bacteria, and fungal infections can mimic phytoplasma symptoms.  The picture below is a willow oak branch displaying some weird symptoms.  What’s causing it?  Phytoplasma?  Sure.

'Crispy black stuff'

Wood decay fungi come in many shapes and sizes.  Their fruiting bodies are generally pretty easy to identify.  Mushrooms and conks along the base of a tree or attached to the trunk can be eye catching.  One commonly over looked and miss identified structural root/basal decay fungi is Brittle Cinder Fungus (Kretzchmaria deusta  formerly Ustulina deusta).  Brittle Cinder causes a soft rot that breaks down cellulose and hemi-cellulose followed by lignin.  This creates a decay that leaves wood feeling brittle.  Early stages of this decay can be hard to detect with a traditional 1/8th-inch bit and drill.

Perhaps the hardest part of identifying this decay fungi is simply noticing it.  Brittle Cinder fruiting bodies first appear as grey-white masses growing only slightly raised from the bark of the tree.  At first sight, they may be mistaken for dead lichens.  As the fruiting bodies mature, they become black and appear as burned bark.  Deusta means 'burned up.'  Unlike most common wood decay fungi, Brittle Cinder is an Ascomycota versus a Basidiomycota.

Brittle Cinder affects a vast array of tree species,including; beech, oak, maple, and linden.  Infection usually occurs through wounds in the bark.  Brittle Cinder can result in significant strength loss, so careful consideration should be taken if this fungus is located on a tree.

Here, Brittle Cinder is growing on the root flare of a red maple.  There is only 1.5-inches to 0-inches of sound wood around the affected area.

Well that's something

While looking at some storm damage a few weeks ago I happened upon this pear.  Like many pears it was cursed with multiple co-dominate stems that tore from the tree during high winds and rain.  While there is nothing special about a flowering pear breaking in a storm event, what's cool about this tree is what was exposed after the tree failed.  The limbs that failed pealed down the trunk to expose branches pruned in the past.

This pear offered a rare glimpse of how trees create new wood around the stem and branches, from the inside.  If only we could dissect some more pears for the greater good, enjoy the pictures below.

You can clearly see the remnants of past pruning.

Another view of past pruning wounds exposed when a portion of this tree failed.

What's your design intent?

Our landscapes, no matter how manicured or wild, are artificial.  By artificial I mean, they are heavily influenced by we humans, not unlike the interior of your home.  Some of us have rooms which are color matched perfect to patterns and furniture that's strategically placed, while others may have rooms that are more eclectic.  Like our interiors, our landscapes are subject to change based upon our discretion.  Few people will have their first living room couch, still, in their living room after-long.  It's accepted that tastes and styles will change with interior design, and it's ok for the same to happen with the plant life in your yard.  Just like you would throw out an end-table bought at the discount store when it became scratched, some plants are worth culling if you're not attached to them, or if they become a maintenance concern.  Conversely, you may take great pains to restore an heirloom grandfather clock, and so you may with a centuries old oak tree.

As your couch becomes older it probably won't be getting larger and encroaching upon other parts of your home, as your trees and shrubs may.  Mature plant size, placement, and the intent of design (as landscape architects put it) are paramount when choosing trees and shrubs for the landscape.  We all want immediate results, but immediate results in the landscape can mean high maintenance costs or whole tree/shrub removal in the future.  The latter are fine, as long as you understand them from the start.

While redoing a room in your home can be completed fairly easily, sometimes achieving that intent of design in the landscape can be a process.  When landscapes are young, they usually look good.  The plants are all small, healthy, and well spaced. Then, just like all little children, your landscape hits adolescence, and suddenly things don't look as cute and pretty.  Not everything is growing at the same pace, some plants are dead, or dying, and things are generally awkward.  This is where having a design intent is important, and where keeping to it can be difficult.  Many people will want to take action, and maybe some action is needed.  This may include replacing a few plants, doing some fertilizing, or pruning, but should not be drastic as replacing whole swaths of landscape.  Keep in mind, many of your favorite gardens and arboreta (Longwood Gardens, Kew Royal Botanical Gardens, The Morton Arboretum, The Arnold Arboretum, etc)  began with young and immature plants.

Change in the landscape is good, and something I encourage my clients to do.  Why nurse along an old decrepit azalea, when it can be replaced by one of the new Encore varieties.  That being said, staying the course is often the best way to go, because one day that spindly     name your favorite tree   is going to be magnificent.

These trees were 3-inch caliper when planted a few years after WWI.  They are now close to 40-inches DBH

Stressed out?

Explaining how trees react to stress can be difficult.  Trees may take years to react, or show signs, of past damage.  Symptoms of construction activities can take up to 8 years to reveal themselves.  This fact can leave many people skeptical of we arborists.  How can a seemingly healthy tree suddenly, and for no perceived good reason, start falling into decline?

The following small scale example attempts to illustrate how tree stress takes time to manifest.  A willow oak sapling was cut in the 2nd week of June in Charlotte, NC. Let's see what happens:

0.5 hours after being cut on a warm summer day in the afternoon.  The tree still looks green and healthy.

About 25 hours after being cut, still green with little signs of stress.

51 hours after being cut, the tree is beginning to wilt and the leaf edges are beginning to brown.

75 hours after being cut the tree is almost completely necrotic, though the twigs are still pliable. 

Larger trees, with less extreme but compound stresses, take time to show symptoms of damage.  The tree in the above example was dead on day 1, but it took 3 days to show it.  When diagnosing tree problems, a detailed knowledge of site history can be crucial when developing a tree care plan.

Who blew it!

Golf course managers are good at managing grass, not trees.  Somehow I ended up playing golf in Miffiin, PA a few weeks ago.  Now, I'm not much of a golfer, but any excuse to be outside in one of the picturesque Central Pennsylvania valleys is a good one.  By about the 3rd hole I started noticing most of the spruces where leaning in the leeward direction.  They had been in this position for awhile, as self corrected leans were evident.

When trees are subjected to a constant force they begin developing reaction wood.  In the case of these neglected golf course spruces, structural roots on the windward side (tension side) of the trees were predominate.  These trees were left to topple over, but refused to give in.

When assessing a tree's risk for failure we must take an in-depth look at the tree.  From a peripheral view, most of the spruce trees on this course looked like they were ready to fail at any moment.  However, on closer inspection, self-corrected leans and adequate reaction wood were evident.

This spruce has quite a lean, but look at the crown architecture.  If the stem was not in the picture the tree would look perfectly up right.

Reaction wood in the structural roots, compensating for the lean.

Another view of 'beefy' roots holding the tree up.