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Nandina berries are killing birds

A few years ago I was at a tree conference and Doug Tallamy of the University of Delaware was presenting on oaks and native gardening. He made an off the cuff remark about berries from the nandina shrub (Nandina domestica, a.k.a. sacred bamboo or heavenly bamboo) being toxic to songbirds and just continued with his talk, apparently unaware of the moans, murmurs and concerned whispers among the audience. This was bad news to many of us.

While labeled an invasive,  ‘noxious’ weed by the US Department of Agriculture, nandina has been favored by gardeners around the world (including myself) for many reasons, one being the winter aesthetic interest it provides with its clusters of red berries (see image). Berries that are killing songbirds, apparently. Just as one example, in 2009 researchers at the University of Georgia found conclusive evidence of nandina berries inducing cyanide poisoning in migrating cedar waxwings. Typically this is a berry birds will avoid but in late winter and early spring, when resources are diminished and birds turn to a berry-heavy diet, nandina can easily find its way on the menu.

If yanking out this plant is not an option, one thing we can consider is pruning off and disposing the berries before birds start feeding on them. Just food for thought.


The Root Cause of Tree Problems

Whether it be insect pests, fungal diseases or simple decline, many tree problems can be traced to the tree’s root zone, to what is happening beneath the soil surface. We tend to overlook this fact, first, because the root zone is hidden and it is only natural to focus on what we can see and, second, trees can be very delayed or subtle in showing signs of stress or decline due to root impacts. As a result, by the time we notice a problem it is often too late and we begin treating the symptoms we can see while ignoring the root cause. Dare I say that we end up barking up the wrong tree?

With this in mind I have listed below the most common human-induced tree ‘stressors’ that I encounter in my work. General approaches to addressing these stressors are mentioned just to get you thinking but for details on what you can do or what you may need professional help for please contact your local extension agent, Division of Forestry office, or certified arborist listed by location at Other online resources are listed at the end.

  • Compaction: A ubiquitous slow killer of trees. Much of a tree’s critical root functions occur within the top 6 to 12 inches of the soil surface. An equal mix of air and moisture are required for those functions to take place and it does not take much to crush and smother that critical zone. Avoid driving or parking vehicles under trees – this should be a ‘no go zone’ for anything heavy, ever.
  • Mechanical damage: Trenching through a tree’s root system or any excavation that leads to change in soil grade can dramatically impact root health. There are amendments and other treatments to mitigate these impacts but the best thing is to avoid the damage in the first place.
  • Poor soils/wrong tree: We rarely have control over the soil environment in which we plant our trees but if we know the limitations we can choose a tree more suited for the existing conditions. Before planting, get your soil tested and make educated decisions on tree species based on the results. And if you have an existing tree under duress, a soil analysis can suggest an underground approach to improving the tree’s health. Often this requires patience, expertise and specialized equipment.
  • Planting too deep: If there is no trunk flare at the base and the tree looks like a telephone pole coming out of the ground, this could suggest stunted and malformed root development, including ‘girdling roots’ that can strangle one another or the trunk itself. This is very difficult to correct as it may require excavation, so proper planting is key! And never pile mulch or soil on the trunk (see image of ‘volcano mulching’) – that is basically the same as planting too deep and can promote insects, rot and disease.
  • No mulch or organic matter: While improper mulching can be harmful, including a layer of organic matter at the base of trees provides numerous benefits, both immediate and long term. If nothing else, with mulch you will avoid the age-old conflict with turf grass that outcompetes for nutrients and moisture, and encourages ‘lawn mower’ disease that is a pernicious killer of trees on a massive scale.
  • Improper watering: Slow and deep irrigation is the key. This will prevent the water from scattering laterally along the soil surface and ensure that more roots develop deeper in the soil, building the capacity to withstand periods of drought. To prevent the establishment or spread of disease avoid sprinklers or anything that splashes or might wet the tree’s bark. Finally, be sure you have a watering plan before you plant any trees, and don’t forget that even large, established trees may need some water if they show signs of decline.

Roots are a tree’s life source. So even if you see a problem high up in the crown, remember that you might be standing on the solution.


Online resources:

Urban Tree Foundation –

Casey Trees How-To Guide –

US Forest Service Tree Owner’s Manual (downloadable copy) –

Volcano mulching can be a slow tree killer

Volcano mulching can be a slow tree killer

Do Ash Treatments Work? One Anecdote Speaks Volumes

TREES 101 has entered its fourth year of treating ash trees to fend off the onslaught of the emerald ash borer (EAB). The method I use – injections of Tree-age® – must be repeated every two years so as time passes I have had the opportunity to return to client properties to perform follow-up treatments. In many ways this is a moment of truth. Ash trees are succumbing throughout our region at a rapid pace and if any of my clients’ trees are still standing and in apparent good health, that is a strong suggestion that the treatments are working.

Admittedly there are a handful of locations where a small proportion of the trees treated have succumbed. In every instance we were aware of heavy EAB pressure and the likelihood that the trees were already infested at the time of treatment. The question was HOW MUCH of a given tree’s crown was already impacted. Those that were too far gone may have initially taken up the pesticide but did not have the capacity to distribute it throughout its vascular system and fight off the havoc wreaked by EAB. In other words, the treatment was done too late to save the tree.

On the other hand there are numerous examples of success. I was recently on a client’s property on the Potomac River where I had treated seven ash trees in 2015. Their home is nestled in 12 acres of woods that has a considerable ash population but due to practical considerations we only treated the trees immediately around their house and near other high-use locations. Every treated tree appeared to be in good condition, while a grove of ash trees less than 50 yards away showed dramatic signs of EAB infestations. The first image below is that of a treated tree, and below that is one of many from the nearby grove (notice the ‘blonding’ effect of woodpeckers flecking the bark). Dramatic.
Reynolds property_2015 treated ash

Reynolds property_untreated ash
Sometimes as an arborist I don’t know how to feel about this. It pains me to see the rapid loss of such beautiful and valuable trees in our region (and now throughout 30 states in the US!) but at the same time it is rewarding to see the benefits of my work. Mixed feelings also come about by the fact that, although the method I use is considered safe and low-impact, this involves the use of a synthetic chemical being introduced to natural plant life. For now I am confident that I have approached my tree work with moderation and balance at the core but there is always room for improvement and contemplation, hopefully not too much rumination…

Have ash trees? Read this

Have ash trees? Read this.
Since their introduction in the late 1990’s emerald ash borer (EAB) beetles have wiped out millions of ash trees across 26 states and have been decimating trees in our region for several years. Despite the beetle’s growing notoriety, though, I still get calls from community members who are frustrated, if not angry, that they didn’t learn of this threat until after they see their trees succumb to an infestation. “Why wasn’t I aware of this?” or “someone should have let us know,” are familiar refrains.
As a consulting arborist I have been reaching out to spread the word but perhaps not well enough. So, for those reading this who might own, manage or recreate around ash trees and have yet to develop a plan to address the EAB threat, this information is for you.
There are two basic options for dealing with EAB – do nothing or have your trees treated this year. The do nothing option is absolutely valid and may be the only practical choice for some, whether due to financial cost or concerns over using chemical pesticides. It is important though to be aware that any ash trees left untreated will eventually be attacked by the beetle and die. It is not a question of if but when, and it will likely be soon.
To prevent tree death treatment is required. There is a ‘soil-drench’ chemical product for homeowners that works systemically within the tree’s vascular system but many shy away from using this as it is mostly a preventative treatment and rarely works if there is an existing infestation in the tree. Additionally, there are growing concerns over the impact this method may have on water quality and the local ecosystem.
The safer alternative – of course, any use of chemicals comes with risks – is an injection method by which the pesticide is fed directly into the tree’s vascular system through injection holes drilled into the trunk. Imagine an intra-venous (IV) system with multiple needles and pressurized with a bicycle pump. Sounds crude but it has proven highly effective, reliable and affordable.
Using this injection method and the right pesticide can even work in trees already impacted by EAB but treatments are far more likely to succeed when applied to healthy trees. In other words, do not wait until signs of distress (decline in the crown, sucker growth, or ‘flecked’ bark with D-shaped exit holes – see image) as this may mean that it is too late. If your tree looks healthy, this is the year to begin treatments. The ‘wait and see’ approach will not work.
Spring is just around the corner (hooray!) and so is another EAB life cycle (boo!) but there is plenty of time to come up with a plan and I encourage you to do so before the growing season is upon us. To learn more about EAB or simply how to identify an ash tree visit or contact your local extension service, Division of Forestry office, or certified arborist.
Shawn Walker of Trees 101, LLC is a consulting arborist based in Shepherdstown.




Time to hunt for pawpaws

Prime Pawpaw Pickin’

I walked up to a pawpaw tree the other day and gave it a shake. The earthy plunk of two distinctly large and tropical looking fruits at my feet told me that pawpaw season had begun. The ripeness of the fruit was quickly verified as my wife and I dug in and enjoyed a vanilla-banana-mango custardy rush of sweet carbohydrates that only nature could conjure. This happened on September 7, early for pawpaws in our region, but if they fall from the tree with a gentle shake, the game is on. So now through the end of the month is your chance to get out there and enjoy this bounty for yourselves.

Despite its tropical appearance the pawpaw (often spelled ‘paw paw’, with a space) tree has a huge native range within the United States and can be found as far north as New York. It is small to medium-sized and often situated in the forest understory, making it quite accessible although the fruit is usually formed high in the tree. The fruit is on the big side (up to 6 inches long) but their color and location make them tricky to spot. This time of year the easiest way to find a pawpaw is to look for the leaves. They are simple and nondescript but quite large (picture the size and shape of a magnolia leaf).

In recent years the pawpaw’s shade tolerant and deer resistant traits have allowed it to flourish and expand beyond traditionally known habitats. Some refer to the tree as a new native weed but more often people realize that pawpaw in the lower canopy beats the non-native alternatives that provide limited benefits and further displace native vegetation. My point? Pawpaws are out there in abundance and they are waiting for you.

If the wild hunt is not for you, a commercial market is slowly developing and you may find pawpaw fruit or pawpaw products (ice cream, pie, salsa) at specialty markets or restaurants. It is a delicate fruit with a short growing season so will require the effort of pawpaw enthusiasts to find ways to make it more available to the masses. One such enthusiast and expert is Neal Peterson of Peterson Pawpaws ( who has developed several pawpaw tree varieties that produce reliable, high-quality fruit. He is based in Harpers Ferry but has become known nation-wide and is working on building an international market for this distinctive delecacy. Some of his trees are available for purchase from specialty nurseries in the region so why not grow your own?

Happy pawpaw hunting.

Shawn Walker is a consulting arborist and owner of Trees 101, based in Shepherdstown, West Virginia. (

Thousand Cankers Disease Threatens Black Walnut Trees

TCD: A Threat to Our Black Walnut Trees

Ash trees in our region have been hit hard by the emerald ash borer (EAB). In my work with clients last year I came across numerous dead trees. And even among the living ones we would choose for treatment a significant proportion showed signs of infestation ranging from decline in the crown to larvae revealed under the bark. If you have ash trees on your property and have not taken steps to address EAB now is a good time to contact an arborist or forester to come up with a plan.

Well, guess what? There is another threat to our trees looming on the horizon. It is called thousand cankers disease (TCD) and it aggressively kills black walnut trees. TCD results from a fungal pathogen native to the western US transmitted by an insect called the walnut twig beetle. A few years ago the disease was detected as far east as Tennessee and it has been working its way up the I-81 corridor since then. Warming climate conditions are pointed to as a promoter of this spread.

Treatments for the disease itself are not available so the remaining options include controlling the beetle and/or making plans for walnut tree mortality in coming years. I have learned from University of Maryland entomologist Mike Raupp that good control of the insect in individual trees should be possible using the same chemical some arborists use for EAB control (Tree-Age® or emamectin benzoate).

There are no reported detections of TCD in West Virginia but the state has issued an exclusionary quarantine due to confirmed detections in surrounding states (see quarantine map from In my unofficial opinion this means that the disease is present in parts of our state and it is simply a matter of time before it is detected.

tcd quarantine map

According to West Virginia’s Department of Agriculture black walnut has an estimated value of $500 billion in the eastern US. Additionally it comprises a significant portion of our forest ecosystem and is a cultural favorite of many West Virginians. I have met people who think of their walnut trees as their college fund – plant a grove at the time of your child’s birth and harvest the timber in time to pay for college tuition. And how many woodworkers out there appreciate the beauty and versatility of walnut wood?

If our experience with EAB is a guide, we should not wait until TCD is recognized as a region-wide problem before developing a plan. We got caught behind the curve with our ash trees and should take steps to keep ahead of the curve with our large walnut tree population.

Visit this multi-agency website for more information on TCD:


Why Are My Leyland Cypress Trees Dying?

As a consulting arborist I get this question a lot. And it’s no wonder when you think about the dramatic decline Leyland cypress have been undergoing. Throughout the region we can see the dark green foliage transition to a reddish brown then an ugly dead grey.

There are a handful of pests and diseases that commonly attack Leyland cypress but the primary culprit here is winter damage. The past two winters (one with a late freeze and the other with a deep freeze) were simply too extreme for many of these trees. As a hybrid of two Pacific Northwest species Leyland cypress are simply not designed for the winter extremes of our zone.

With some plants winter damage is obvious but it is trickier with waxy-leaved evergreens like the Leyland cypress. First of all the desiccation and dieback take a while to manifest, causing us to notice the impacts well after the fact and over an extended period of time, similar to what we see with the spread of disease. Second, the stress caused by winter damage makes the tree more susceptible to its common enemies, especially canker diseases, and it is possible that the final death blow is actually delivered by one of these secondary impacts. Visit this link to learn from West Virginia University’s extension office about canker and its role in Leyland cypress decline:

I see three basic management options:

  1. Do nothing. Let the damage run its course but run the risk of dead wood decay working its way into healthy tissue and causing further damage. You also run the risk of canker disease developing, which is even more likely spread to other parts of the tree or to other Leyland cypress trees.
  2. Prune out dead sections and/or remove dead trees. What is dead is dead and will not ‘fill in’ over time. Cutting out these sections minimizes further decay and reduces the likelihood of disease. Use sharp tools and be sure to sanitize them with alcohol or bleach solution when you move from one section of the tree to another or from one tree to another. If you suspect a disease like canker consider spraying the tree with a fungicide after pruning (and possibly during the following growing season). I recommend neem oil as an option that is biologically derived and has minimal impact on beneficial insects.
  3. Replace with hardier diverse species, keeping an eye toward natives. If you avoid monocultures you avoid the likelihood of a single pest or disease – or frigid winter – taking out your entire population at once. And consider wildlife habitat by planting native species such as eastern red cedar (a prime habitat tree), eastern arborvitae (a.k.a. eastern/northern white cedar) and eastern white pine. Native shrubs will also fill in a space very quickly and increase your butterfly and songbird visitors.

Finally, a word about watering. No matter their age, any stressed tree will benefit from a slow, deep irrigation (e.g. irrigation bags, soaker hoses, buckets with tiny holes) during hot dry periods. In fact, some suggest that newly planted or stressed Leyland cypress should be watered well into October or November to ensure that they have the vigor to withstand the stress of a harsh winter.

Shawn Walker is a consulting arborist and owner of Trees 101 ( based in Shepherdstown, West Virginia.

Last Chance to Protect Ash Trees from Emerald Ash Borer

Last Chance to Protect Your Ash Trees

(For those in West Virginia’s eastern panhandle and nearby Maryland, Virginia or DC)

 If you own or manage ash trees and they haven’t already been killed off by the emerald ash borer (EAB), this year is your last chance to take proactive measures. Over 20 states in the US have been impacted, with tens of millions of ash trees lost, and all of West Virginia is under state and federal quarantine for movement of wood. Sadly, if you are in the eastern panhandle it is likely that your ash trees are already infested with EAB.

Given this reality, here are your management options:

1)      Have your trees treated. It is probably too late for preventative treatments so talk to a certified arborist about injecting your trees with a ‘therapeutic’ product called Tree-age® (emamectin benzoate – not a neonicotinoid). There is a biologically derived (or ‘organic’) product called Tree-azin® that gets mixed reviews but is a greener option worth considering. Of course there is financial cost involved but many people find it well worth it when they consider the alternative.

2)      Have select trees treated. If you have a woodlot or just too many trees to address, choose one or a handful of specimens to protect until EAB have wiped out all non-treated ash in the region and move on. The theory is that this will leave you a living ash tree legacy that can provide seed for later generations. Provincial foresters in Canada are experimenting with this in their managed forests and I find it an intriguing strategy.

3)      Sell trees for timber. If EAB have not impacted the quality of wood, there may be some monetary value in having your ash trees harvested. At the very least they can serve as a source for firewood.

4)      Have tree removed. If in a frequently used landscape (your backyard for instance?) and treatment is not an option, have the tree removed by a licensed and insured tree professional as it will soon pose a safety risk as a standing dead tree.

5)      Do nothing. If in a natural area there is little harm in simply letting your ash trees succumb to EAB and eventually serve as organic matter for the forest floor. Just remember that in five years or less, these trees will be standing dead snags and can pose a hazard in some circumstances.

We have recently learned that EAB have also been attacking white fringe trees, a close relative of ash, and that our ubiquitous yet cherished black walnuts may be threatened by a new pest in the near future. Boy, oh, boy. One headache at a time, right?

For more information on EAB, visit this multi-agency website:

The nearby Inwood office of West Virginia’s Division of Forestry can be reached at 304-229-2665.

Shawn Walker is owner of Trees 101, a consulting arborist business based in Shepherdstown. Website:


Structural Pruning In 3 Easy Steps

A Tree’s Formative Years: Structural Pruning in Three Easy Steps

When is the best time to prune trees? I find it hard to give a simple answer to this frequent question. It depends on the tree and the circumstance but I usually boil my answer down to these three points:

For those perfectionists that are good planners and want to get it done just right, dormant season (winter) pruning has the most advantages. These include avoiding the spread of disease; minimizing stress; maximizing the tree’s ability to seal pruning wounds through the upcoming growing season; and the lack of leaves (on deciduous trees) revealing branching structure and allowing you see what you are doing!

However, sometimes I say the best time to prune is when you can. If you use clean, sharp tools and proper technique, don’t sweat the timing. Note that if your tree species is susceptible to pests that attack during the growing season, avoid late spring through mid-summer.

Finally, I answer the ‘when’ question in terms of at what point during the tree’s lifespan. Answer: when the tree is young and has recovered from the shock of planting. This is when branches are reachable and pruning cuts will be smaller and likely to seal completely. Most importantly, these are the tree’s formative years and, as with us humans, this is a chance to provide guidance and direction, setting the youngster on a trajectory toward a long and healthy future. This is done through ‘structural pruning’, a pruning technique that can be performed by following three simple steps.

Step 1: Remove any dead, diseased, or damaged branches (the three D’s), as well as those that are crossing or conflicting with other branches or permanent structures (your house, for example!). Also prune out any suckers or sprouts growing from the tree’s base or along its stems, respectively. Before moving on to Step 2, take a look at how much was removed as a result of this step. If you have removed 25% or more of the overall crown, wait until the following year to move on.

Step 2: Address any ‘co-dominant’ stems, i.e. those that are competing to become the central leader/trunk. It is not always possible but your tree will exhibit superior structural strength (and associated health) in the long term if it is encouraged to develop with one dominant trunk. Remember, ‘There can be only one leader!’ So if you have co-dominant stems, pick one to encourage then either eliminate the other altogether or subordinate it by reducing it down to a smaller lateral branch.

Step 3: Address spacing along and around the trunk. In your mind’s eye, picture a spiral staircase and see if you can nudge your tree in that direction. In large shade trees the major ‘scaffold’ branches should be three to five feet apart along the length of the trunk with few branches whirling around the trunk at a single point (a losing battle with some species). When structural pruning a young tree, aim for a spacing of 12 to 18 inches along the length of the trunk.

These three steps to structural pruning will give you added confidence that your tree will grow to be big and strong, making you a proud parent.

There is much more to consider regarding proper pruning cuts and mistakes to avoid so if you want to learn more, here are a few online resources that can help:
Urban Tree Foundation –
Casey Trees How-To Guide –
US Forest Service Tree Owner’s Manual (downloadable copy) –
US Forest Service How to Prune Guide –

A note about safety: Always wear gloves and safety glasses. Use the right tool for the size and location of your cuts – a homeowner’s pruning kit might include hand pruners, loppers, a pruning saw and a pole saw with a lopper attachment. If pruning large branches above your head, wear a hard hat and never prune near utility lines. For larger jobs, consider hiring a professional arborist certified by the International Society of Arboriculture. You should not need a chainsaw for structural pruning.

Shawn Walker, owner of Trees 101 (, is a certified arborist and a registered consulting arborist based in Shepherdstown WV. Email:

Treating Emerald Ash Borer in West Virginia

As a consulting arborist based in Jefferson County I have observed the emerald ash borer’s devastating impact on the ash tree population throughout the eastern panhandle of west virginia over the past few years. The imported beetle is sweeping through the region at such a rate that many people are being caught off guard. I have seen a wide range of management approaches taken by homeowners, municipalities, and other tree managers, and would like to share my experience with one particular park in Shepherdstown.

My wife and I moved to Shepherdstown about a year ago and we quickly got to know Morgan’s Grove Park as it is nearby and an excellent place to take our dog for a stroll and frolic. The tree freak in me quickly realized that a large proportion of the mature tree population in a highly used section of the park comprised green ash. I was naturally curious as to how Jefferson County was approaching their emerald ash borer management so I started asking around. Interestingly, although the park functions as a public park and is maintained through contract by Jefferson County, it is actually owned by a private entity (Shepherdstown Community Club), so I arranged a conversation with one of their board members to get the details.

I learned that the community club had been researching EAB but had no active management plan. It was then my obligation to explain the dramatic impacts already exhibited in surrounding areas and that they had to assume that all of their trees would be standing dead hazards within a few years if no action was taken. (This meant they would lose about 75 mature ash trees averaging 19.5 inches diameter at standard height, including West Virginia’s third largest green ash on record.)

The conversation quickly turned to their management options, none of them appealing to a non-profit organization with a limited budget. They could do nothing and be prepared for the risk, expense and dramatic impact of canopy loss in a park heavily used by the public. Or they could treat some or all of the trees, realizing that some trees may already be infested and that the success of treatment is not guaranteed. For treatments I recommended trunk injections of Tree-age® (emamectin benzoate). The injection method because it would minimize any unintended environmental impacts and risk to the public. Tree-age because it is the only insecticide recognized by arborists to be both preventative and therapeutic, actually showing capacity to halt preexisting light infestations of less than 20 percent of crown. Plus, it allows for an interval of two years between follow-up treatments.

I assume there was some deliberation but within a few days after our meeting, the Community Club contacted me saying they had decided to have all of their ash trees treated in an effort to protect their existing tree canopy. As it just so happened, I had obtained my WV pesticide applicator’s license a few months earlier and was able to offer to do the work that they needed. We drafted up a contract and I stocked up on Tree-age and injection equipment.

I spent every day of the last two weeks of May at Morgan’s Grove Park with my trusty Tree IV® kit performing trunk injections. The weather was cooperating and the trees took up the Tree-age at a quick rate. The entire process took from 20 minutes to one hour for each tree, depending on overall size and health. By the end of the month I could confidently say that every ash tree in Morgan’s Grove Park (in fair or better condition, a total of 73 trees) had taken up the Tree-age and that if their ash trees were going to survive the EAB onslaught, the Community Club had taken the best steps to give them a fighting chance.

If Morgan’s Grove Park were a municipally owned park, it is hard to know if the funds would have been available to take this kind of action. Being an independent organization the Community Club made a quick decision and took it upon themselves to provide the funding upfront and turn to the local community for donations to recuperate the cost. In fact, they started a “Save Our Stately Ash Trees” campaign and have had a remarkable response from donors. And if the ashes still show good health two years from now, the Community Club is confident that the community will step in with support once again. In the name of public and environmental stewardship this all volunteer organization took a risk, and the next couple of years will reveal whether the ash treatments were effective and that they took the right course of action. Or, from my perspective, the next couple of years will reveal whether a certain arborist is deemed the local GOAT or HERO.