With the ice and snow damage fresh on our collective minds and the forecast showing the possibility of more freezing precipitation, it seems only fitting to discuss winter damage and how to protect trees and shrubs. Not only does snow and ice cause damage to trees, but so can cold temperatures and windburn which are not always identified properly. While it’s possible to protect some plants when it comes to large trees, damage can be inevitable, so it’s important to inspect trees following an ice event to make sure that damage has not caused structural issues that are soon hidden by spring foliage.
When ice or heavy snow is in the forecast, it’s good to prepare your small trees and shrubs by protecting them with supplementary support to keep them from bending and twisting in the snow. One of the most commonly damaged groups of plants is evergreen shrubs with multiple interior stems, such as Arborvitaes, Sky Pencil Hollies, and English Boxwoods. By temporarily wrapping the exterior of the plants with twine or even burlap, it’s possible to prevent any damage before the weather event begins. These wraps should always be taken off before spring growth so that it does not limit shoot or leaf expansion.
In some instances, with fragile plants, it makes sense to set up a wooden A-frame structure over plants that has horizontal cross boards that deflect any snow or ice from building up to damaging levels. These protective structures can be put up in the early winter and left up until spring, at which point they can be stored until the next winter.
It’s not always practical to preventatively protect your plants, at which point, it’s important to keep an eye on accumulations during the event so that snow and ice can be brushed or shaken off of the plants. When heavy wet snow builds up on shrubs, it has a tendency to spread out and bend the individual stems away from one another causing damage to the overall form of the plant and often bark damage as well. To prevent this, the plants should be gently shaken or brushed with a broom to knock excess snow loose. This often has to be done multiple times during a storm as it is much easier and less stressful on the plant to gently knock a small amount off rather than further stressing an already stressed branch or stem.
When heavy snow or ice is already built up on shrubs, any extra jostling can cause the stems to snap. With existing heavy buildup, it is often better to leave the snow and ice until the storm has stopped so that the limbs can flex a bit for later removal. Once snow is removed, it’s best to tie up and support any bent limbs as soon as possible to prevent more damage to the bark and underlying tissue when the stem is bent back into place. Leaving limbs and stems bent for extended periods of time will also increase the likelihood of stem damage or death as cracked open bark can allow desiccation before spring growth can close wounds.
Physical damage is not the only threat to plants during winter though it is quite often the most evident and thus easily identified. Cold damage occurs frequently in Central Virginia in the months of January, February, and March when temperatures drop into the teens and single digits. Most plants in the Richmond area can tolerate one to two very cold days without a problem, but extended periods of cold, dry weather can cause significant damage to many evergreens in the area. While cold temperatures can kill some above-ground growth on marginally hardy plants, it is actually the cold temperatures mixed with low humidity that does the most damage, called “winter burn.”
Water will frequently melt in the leaves and needles of evergreen plants from sun exposure even if air temperatures are below freezing. This liquid water can be quickly lost through the leaf cuticle when the humidity is very low causing desiccation and “burning” of the leaves and needles. This damage can be slow to develop and may even show up in the spring when the damaged leaves begin to brown and drop. While it’s impossible to alter the outside temperature, it is possible to limit water loss by wrapping and covering plants with burlap or similar textiles as it limits sunlight on the foliage and also reduces the drying effects of any wind. This protection does nothing to limit freeze damage on marginally hardy plants, but it can be very effective in limiting damage to evergreens.
The final important part of protecting your trees and shrubs is through a thorough inspection following any large snow or ice storm. Especially in ice storms, it’s likely that limbs will split or break without coming out of the tree canopy. This creates weak spots in the canopy, widow makers, and places for decay and infection to enter the plant. Finding damage early is much easier without new foliage on the plants and can prevent new leaves from weighing down an already compromised limb, causing a hazardous failure. Timely removal of damaged branches before spring will allow the tree to begin closing over the wound as soon as growth resumes for the season.
A little bit of time spent before an upcoming storm or even a bit of playing in the snow can help to protect your trees and shrubs from snow and ice damage, but no matter how hard you work, extreme cold is a problem that does not have a solution. If we are unlucky enough to have another visit from the dreaded Polar Vortex again this winter, wrapping plants can buy you several degrees of protection but usually not enough to prevent all damage. Good spring cleanup to remove dead tissue will improve the appearance of the plants and provide room for new healthy growth
It’s an almost universally known fact that trees and actually all green plants are the main source of oxygen on earth. Without green plants, giant or microscopic, life on earth as we know it could not exist. At a young age, we learn that plants take in carbon dioxide and give off the oxygen we breathe. As we age, we learn that plants take in carbon dioxide, water, and nutrients and then utilize chlorophyll and sunlight to break the oxygen free from carbon dioxide and combine it with water (H2O) to create simple and complex carbohydrates.
Plants, and especially trees, essentially create something from nothing. In a natural environment, plants are able to take free resources and create the sugars and cellulose that feed us, clothe us, and shelter us. This is how most of the world sees trees, but there is a hidden side that many people do not understand or really care about, and that is roots. Roots are hidden under the soil, often misunderstood, and most of the time completely overlooked by tree owners. It’s the old adage of “out of sight, out of mind.” Most know that roots provide water and nutrients to trees and act as an anchor, but very few know how roots actually grow and that can lead to many problems.
One of the most surprising things to learn about roots is that they go through aerobic respiration just like animals and need to take in oxygen and give off carbon dioxide to live and grow. Sugars made in the leaves are moved through the tree in a downward flow towards the roots where oxygen and sugars are used to create energy for cell growth. While roots are taking in oxygen, the above-ground portion of the tree is creating much more oxygen than it uses so, as we learned as children, trees and all plants are overall oxygen producers. This surprising fact is made possible by a tiny and very boring-sounding term called “soil porosity.”
If you could take a cross-section of healthy, natural soil, and look at it, it should look like microscopic Swiss cheese or a sponge. The bits of soil, organic matter, and the like should be spaced out by some large and small holes that allow the flow of gas and liquids between pores and into plant roots. These pores allow water infiltration from precipitation and gas transfer and if they are not present, things start to go bad. First and foremost, water infiltration stops so ponding, puddling, and runoff occur, which is an immediate notice to plants and the people living among them. This lack of water flow into the soil can be a nuisance or danger to humans after significant soil disruption, but it is deadly to plants as they no longer have the water that is essential to their growth. This is an acute problem that can quickly bring about the death of a plant, while there is a secondary problem that can take much longer to kill a tree.
While water is the most essential occupier of soil pores, it can still find its way into even heavily damaged soils thanks to its mass that helps it get pulled into the soil via gravity and the surface tension of water that makes it able to flow through even small pores in the soil. The second most essential element for plants’ roots is the exchange and flow of gas in and out of the soil pores. This is where things can go bad without much notice as we don’t see the gas around us and there will never be a build-up of too much gas on the soil as we do with poor water infiltration.
For this reason, soils can be heavily damaged without much attention being paid as tree roots begin to suffocate and die without any sign. This causes a slow and languishing death for the tree as the roots continue to die back closer and closer to the tree. This can easily be seen above ground several years after the damage first occurs in the dieback of branch tips on the exterior of a tree’s canopy. This above-ground symptom usually shows up in a window of 3 to 5 years after initial soil disturbance. In many cases, the root dieback underground has been progressing for so long that the tree is in a steep decline and will be very difficult to reverse without aggressive remediation. With the knowledge of how tree roots work and the essential role soil porosity plays, it’s now easier to understand the main causes of soil damage and how it can be reversed.
The single largest cause of damage to soils is construction, as soil is compressed and compacted either for a solid base for a foundation or simply the traffic of equipment and feet along a pathway. This compaction is essential to our modern infrastructure. Soils must be compacted to provide a stable base and foundation for our homes, roads, and businesses, so not all compaction is bad. It’s when soil is compacted in the root zone of a tree that problems arise. This compaction greatly reduces the soil porosity and can be most damaging when the soil is wet. Roots in areas of compaction are often damaged by construction, but it’s more likely that the soil porosity is greatly reduced and root suffocation begins. As is the case with most things in life, prevention is key.
When working around trees, it’s extremely important to recognize where roots run so that they can be avoided as much as possible while still successfully performing the work. Roots are typically seen as a mirror image of the above ground portion of the tree and this is another significant misconception. Most roots are found within the top 2 feet of soil and can extend well past the drip line of the tree. Roots in most cases stay shallow as that is where the best soil fertility occurs and is where gas infiltration and exchange happens in healthy soils. Many of the small fine feeder roots extend past the drip line of the tree so keeping construction activity far away from the tree is best. If that is not feasible, the general rule is to create a protection zone with a one-foot radius for every 1 inch of DBH (diameter at breast height). Any protection around trees should be a physical barrier with no openings to prevent incursions into the protected zones. Orange construction fence is often enough on small projects but larger chain link fence panels should be used on larger projects. This all occurs when there is proper forethought and planning in regards to the trees, but that rarely happens.
When soil has been damaged due to some form of significant compaction, all is not lost as this can be remediated with proper care and attention. The most important factor is to recognize damaged soil and/or a tree with root damage as the clock begins ticking the first day the soil is damaged. Addressing a compacted root zone or damaged roots directly after the damage has occurred can prevent any significant symptoms of decline and will most likely prevent the death of the tree. After recognizing this damage, the soil must be decompacted utilizing mechanical or pneumatic tools to break up the soil particles and reestablish proper soil porosity. In areas with limited vegetation, a rototiller can be used to break up soil in preparation for planting as newly planted trees and shrubs will not grow well in heavily compacted soils as their roots cannot penetrate the soil at the edge of the dug hole. In newly constructed communities, newly planted landscapes often fail due to high soil compaction that is never addressed. Quite often though, existing plants and their roots must be kept in mind because rototillers will do more harm than good to existing plants.
A simple-looking but highly engineered device called the Air-Spade can be used to blow high volumes of air into the soil to break it up and recreate soil pores all while doing very little damage to existing woody roots. This device used large volumes of compressed air forced through a specially engineered tip that allows the air to break apart soil particles while only hurting fine root hairs that a plant can easily regrow. Large portions of compacted root zones should be tilled using this tool and then composted organic matter must be added to act as a long-term protector of porosity. After the soil is tilled and compost is applied, it is easy for the soil to settle and porosity to reduce soon after the treatment. The organic matter in the compost will slowly break down, feeding the tree a steady supply of Nitrogen and leaving large pore spaces long after the initial soil settling. This process can be a bit dirty and is the more expensive remediation option but it works very well to address damaged soils around existing landscapes and trees.
When we look at trees, we see the good they provide us: shade, wood, food, and simple beauty. But we are only seeing half of the tree. The underground portions of a tree are some of the more interesting parts when you think of the job they do. Without healthy soils, it’s impossible to have healthy roots, and without healthy roots, there cannot be a healthy tree. Keeping roots healthy is easy by limiting soil compaction and keeping a natural nutrient cycle around the tree. Fixing damaged soils can be much harder but it is possible in most cases and can be a fraction of the cost of having to remove the tree. Keep an eye on your trees and watch to see if they are showing you symptoms of decline. Dieback at the top and tips of the canopy is quite often a sure sign of root damage and death.
When it comes to birds and trees, most people see the relationship like peanut butter and jelly or spaghetti and meatballs. They just go together. It’s impossible to think of one without the other, and in nearly all cases, it is a mutually beneficial relationship. Trees provide shelter and food for birds, and birds spread the seeds of many trees as well as control pests that may feed on the trees. As with most things in life, there is always an exception to the rule and when it comes to birds and trees helping one another the yellow-bellied sapsucker (YBS) is that exception. The YBS is a native woodpecker species that damages trees in its search for food and in some cases can even lead to the death or dieback of trees that are the target of this bird.
I first came across the damage of YBSs early in my career when I was called out to diagnose the dieback on a Nellie Stevens holly that was declining and had a dead top. It was easy to see that the stems of the plant had been injured with much of the bark being removed in odd, almost honeycomb-like, sections that had girdled the stem and caused the area above the damage to die. Immediately the thought of European hornet damage arose as these insects are known for stripping back and even some softwoods to create the paper material for their nest building. I was convinced that a bark treatment would prevent future damage and with a treatment applied, I moved on with little expectation of future issues. Optimism was met with disappointment when damage continued and only then did I realize I was facing an uphill battle.
Yellow-bellied sapsuckers are a unique woodpecker species that gets food in many ways including foraging for fruit and insects, drinking sap, and even baiting insects with sap. Most woodpeckers are known for their rhythmic pecking on large dead limbs to excavate insects from decaying portions of trees. The YBS is not a species that likes to wait around for things to happen. They take action to get food coming their way. Just like their name implies, these birds do indeed suck the sap out of trees by pecking away the bark to create a sap flow from which they drink. They are also quite ingenious as they use this sweet flowing sap to attract insects and then eat the insects as they gather. While the reduction of insects around the tree is usually a good thing, in this case, the damage is worse than the benefit.
Damage from YBS can be seen on many different tree and shrub species, but the most heavily affected plants are hollies, maples, pecans, hickories, and a variety of small, thin-barked species that are commonly used in landscapes. The damage usually appears as a series of small circular holes that are present in a horizontal line around the trunk or stem of trees. This damage is commonly mistaken by homeowners as a sign of wood-boring insects, and misapplication of chemicals can easily occur. With smaller trees and on smaller diameter limbs, damage can appear as large patches of bark that have been removed, exposing the wood underneath. It is also highly likely that once a tree has been targeted by YBS that it will be used as a feeding site in the following years, further compounding the damage as more bark is stripped away annually. It’s in these cases that treatment or prevention becomes important to stop stem and branch girdling.
YBS are migratory birds and are protected by law, so there are thankfully no methods for poisoning or destroying the birds, but that does reduce the number of ways to protect trees from their damage. The most effective DIY treatment is to prevent the YBS from accessing the bark. This can be done by netting smaller trees and shrubs to eliminate access altogether or through wrapping of previously damaged stems and limbs with burlap. Luckily, the new fad for parties and weddings is the rustic aesthetic which has introduced a significant number of burlap fabric options, including rolls of burlap ribbon that can easily be wrapped around trees. The only issue with this approach is the cost of materials and the limitation of only being able to protect the tree in areas that are easily accessible.
Another bit of luck is that it can be easy to predict when this protection needs to be installed. The YBS is a migratory bird that uses the Mid-Atlantic region as a stopover during the migration from their summer breeding grounds in the far Northeast to their overwintering locations in the South and Mexico. This places the birds in our region in the early October to November range on their flight south and in January to March as they make their flights back north. Over the years of watching the damage, I have come to see much more damage in our region during the return flight north in the very early spring. I assume that this is caused by a great supply of other food during the flight south in autumn and the relative dearth of food during their northern flight, requiring sap feeding and insect baiting. For this reason, I always suggest homeowners install protection on vulnerable trees before Thanksgiving and then remove any barrier materials before growth begins again in the spring to prevent damage to newly expanding leaves and growing stems.
While the yellow-bellied sapsucker can be a nuisance, it is never enough of a problem to call for drastic measures such as poisoning or killing the birds and should be addressed as such. A little bit of prevention can go a long way on small trees and as trees grow large enough, the birds cannot do enough damage each year to cause much if any dieback or decline. Keep an eye out for these little birds in the late winter and early spring and if you see trees weeping and bleeding during that time, take a closer look. It is likely you will find small holes drilled in the tree and you will know that there is a yellow-bellied sapsucker nearby, filling its belly as it makes its trip back north.
It’s almost time for that favorite fall pastime: leaf-peeping. Soon there will be countless photos of glowing, multicolored trees posted all over social media. But most people don’t really know why trees do this or what color change can indicate if it shows up a little too early. This won’t be a class on biology but will hopefully give you a new insight into what those colors mean and if it is actually a sign of hidden tree issues. With a little knowledge and a little bit of looking up, it may even be possible to determine dying branches, declining trees, or maybe just a tree that’s a bit thirsty.
Most of us learned in school that trees change color in the fall as a way to conserve resources, as pigments such as Chlorophyll, Carotenoid, and Anthocyanins are broken down into simpler chemicals and pulled back into the tree before leaves fall to the ground. These chemicals are recycled in the coming year as the tree puts leaves on in the spring. Changing temperatures and reduced light levels trigger the trees to begin the process of reabsorbing the nutrients. The first pigment to be broken down in the leaf is the green Chlorophyll, leaving behind the less prevalent orange-colored Carotenoid and the reddish to almost blue Anthocyanins. The concentration of these pigments in the leaves of different trees will dictate what color you see.
As fall approaches many people love to discuss whether or not it will be a year with good fall color which can be heavily dictated by the weather in the months preceding. A dry and stressful year for the trees, for instance, usually creates a lackluster fall display. This is because the trees either move through their color change much more quickly or simply drop their leaves without much of a color change. This is a survival adaptation to simply go dormant before the tree has to suffer more stress. A lack of good fall color can also be caused by the inverse: too much rain in the late fall, which floods the leaf tissue with water and essentially dilutes the colors. These stress-induced changes can help us diagnose issues in individual trees.
I have a city sugar maple planted in front of my house, and as with many open-grown maples, it has grown with very poor architecture, with a limb shooting out and trying to become the main leader of the tree. This has left a stunted and somewhat lackluster central stem. Not only is this stem stunted, but it is always the first portion of the tree to change color in the fall while the rest of the tree maintains a deep green background. While this could be seen as a desirable outcome with extended fall color arising from the issue, it actually acts as a signal that something is wrong in the tree. Quite often trees will have one or two low branches or sections that prematurely develop color. It’s likely that those limbs or areas will be unhealthy or even dead in the following growing season. The tree senses a lack of vigor in those areas and takes action to get every last bit of energy and nutrients out of it before evening considering shutting down the rest of the tree.
A similar situation occurs with newly planted trees, which can easily be seen in planted rows of the same species such as those in commercial or community plantings. This time of year the stressed or poorly planted trees will begin to show color much sooner than other adjacent trees as they are hurrying to go dormant before they have to endure further stress. When this occurs, it is almost always a root issue and by identifying these trees, it’s possible to give them the additional support and care they need in the following growing season. A little work on the root zone to improve soil conditions can quickly turn around a tree that is struggling as long as it is caught before the tree irreversibly declines.
Some trees also use early color and leaf drop as a survival strategy to get through the rest of the growing season with color and leaf fall sporadically occurring as early as July or August. This occurs frequently in river birches and tulip poplars as they are both fast-growing and water-loving trees. In the spring these species put on large amounts of growth when water is plentiful and as the rain reduces in the summer, the trees need to cut back on their water loss from foliage. Leaves scattered throughout the canopy begin to turn yellow and fall, causing a concerning site for the tree owner. This reduces the overall leaf surface area on the tree and thus reduces the loss of water from the tree, allowing it to maintain proper moisture levels even when rain is scarce.
One dissimilar situation is the tree species that simply drop their leaves earlier than most others. Black Walnuts are a peculiar tree as they are nearly always the first tree to drop their leaves and the last to put new ones on in the following year. This has nothing to do with stress. It’s simply the natural characteristic of the species. Ash trees also drop earlier than many other species but can put on quite the show when they do, creating an almost glowing canopy of many different colors.
While not all trees provide showy fall colors, we’re lucky in the region to have many that do. But don’t dismiss the colors as just an aesthetic benefit. Pay attention as the show may actually be the tree signaling an issue that needs attention. Here’s to what will hopefully be a fall filled with lots of happy and dazzling trees!
With a taste of cooler temperatures last week and fall-like weather right around the corner, I find myself planning more adventures, get-togethers, and festivals now that I won’t melt under the summer sun. These adventures find me moving all about the greater Richmond area, from Ashland to Petersburg, and when I find myself to the southern end of our region, I always do my best to carve out a spot of time to visit my favorite tree.
The Cucumber Tree Magnolia (Magnolia accuminata) in Colonial Heights (click here for Google Maps location) is one of the more visually striking and almost otherworldly trees in the area and deserves a visit if you make your way to the Colonial Height and Petersburg area.
The tree sits in front of the Violet Bank Museum in Colonial Heights overlooking the Appomattox River and Old Town Petersburg. When viewing the tree for the first time, it looks almost comical in size and stature next to the relatively small museum building with its white peeling paint. This backdrop is somewhat fitting though as the tree is aging and is beginning to show its threadbare spots. With estimations of it being at least 200 if not 300 hundred years old, this gradual deterioration is to be expected and is actually quite limited. This particular Cucumber Tree Magnolia is also estimated to be the second largest of its species in the world, with a nearly 23-foot circumference, making it that much more spectacular.
The idea of a record-holding tree usually conjures images of extremely tall trees with enormous towering crowns, but that is not this tree. Instead it’s almost the inverse with a relatively stout height but an extreme girth and outstretched, over-extended limbs that are trees in their own right. The first main scaffold limbs on the tree are at least 24 inches in diameter. They gracefully extend until their massive weight pulls them to rest on the ground. Large pockets of decay can be seen in several of these limbs, so without the support on the ground, these limbs would have likely torn from the tree decades ago. The tree took action to support its failing limbs on its own while many failed attempts by human intervention can be seen on the tree.
Viewed up close, a variety of failed arboricultural practices can be seen almost as a museum in itself. Large pilings have been placed in the ground to hold up several of the low limbs, which can be argued do as much if not more damage than the tree supporting itself on the ground. Scattered throughout the canopy are decades worth of steel cables and supports that long-ago arborists installed to maintain the tree and with time many of them have broken or gone slack. It’s most interesting to see such failed support systems hanging from limbs that have once again provided their own support on the soil. One very odd addition to the tree is an old technique used to cover holes and cavities in trees: the much dreaded concrete. A large over-extend limb obviously had a decay spot in the past and well intentioned caretakers took on the project of filling the void and sculpting a brick pattern into the concrete wedge place in the limb. As arborists now know, concrete is never a good choice for filling wounds and this tree is the poster child as the branch is now almost completely decayed leaving behind a brick textured chunk of concrete clumsily sitting inside a once-enormous branch.
When I began my career in Richmond caring for trees, I was appointed the task of monitoring and caring for this amazing tree. As I learned more about it, I felt a real weight on my shoulders to care for it. This weight eventually turned towards reverence as it became clear that my input was likely inconsequential. It has lived for easily over a century before I was born and, barring a catastrophe, will likely outlive me. This tree has seen more history than we can imagine and is even rumored to be a campsite of high-ranking leadership during the Civil War’s Battle of the Crater. If you find yourself south of Richmond this fall, I highly recommend stopping in to see this remarkable tree before nature or man cause its decline. Take a moment to appreciate what this tree has seen and all of the adversities it must have overcome to grow so large and survive for so long.
It was several weeks ago that I received a phone call from a colleague in the tree care industry asking me if I had seen a lot of bark coming off of sycamore trees around Richmond, and it sparked the realization that, yes, indeed, I had.
While this is not an unusual thing to see when large amounts of bark begin to fall, alarm and concern are the first reaction from homeowners as many believe falling items must indicate a problem with the health or safety of the tree. In many cases, when bark splits, exfoliates, or simply falls off, it can be a sign of a very healthy and happy tree. The important thing is to be able to identify when it is a good sign and when it can be a sign of bad things to come.
It was only a few years ago that Richmond had several very wet summers, and many area trees showed their appreciation by growing in a way that we had not seen in quite some time. Not only did their annual growth rings show an increase in growth and wood production, but the thin-barked trees created lasting signs with splits and fissures in the bark along the stems and branches. This can be equated to stretch marks as the trees grew too quickly for their skin and had no other option than to split and create wound tissue to allow for the unexpected growth. Remember, that trees will grow as much as they can in a growing season only limited by their resources which is almost always water in Central Virginia. When bark splits, it can be a very distressing sight but as long as only the bark is splitting without any wood damage or bleeding from the area, it is likely not an issue.
Similarly, many thin bark trees such as sycamores, crape myrtles, and lacebark elms shed sections of their old bark as the tree grows and new bark develops. This usually occurs in mid-summer at the peak of growth creating a bit of a mess around the base of the tree. Luckily the bark is always quite thin — almost papery. Many of these trees are actually planted for this characteristic. The new bark is usually colored differently, so the stems develop a pleasing aesthetic. When this occurs, do resist the urge to help the tree out by pulling the old bark off prematurely. This can expose newly developing bark that is not yet ready to be exposed. Trees with exfoliating bark are a wonderful addition to the home landscape as they often add welcome visual interest during the dormant season.
There are also a lot of trees that begin to shed blocky, thick bark as they develop into maturity leaving behind small and somewhat uncharacteristic bark. This is very common in tulip poplars, flowering dogwoods, and even white oaks to some extent. This is also quite concerning to tree owners as the tree has grown for one way over a very long time and then begins to change in a location, usually around the base of the tree, that does not seem logical. Due to the size and maturity of these trees, it is likely a good option to have an arborist take a look, due to the risk the tree could pose if the bark change is a sign of something a bit more sinister.
When trees lose their bark in what seems to be an extreme amount, when it is occurring in the upper canopy of the tree, or when you can see decay or exposed wood behind the bark, it is usually a sign of damage or decay. These are the situations that would require the need for an arborist to examine and diagnose what may be causing the problem. Several diseases will cause the death of the cambium directly under the bark of the tree which allows the bark to detach from the tree and come off in chunks. These diseases can kill the tree if left unattended and loose-but-still-attached bark can become a breeding ground for pests. If there is a question about bark loss, it can be a simple as taking a picture of the area, identifying the species of tree, and sharing it with an arborist to determine if it is a cause for concern.
If you have lived in Central Virginia for any period of time, you know that the weather can keep you on your toes. And if you don’t like the conditions, wait an hour, and things will probably change. This can make gardening and keeping your plants and trees healthy a real challenge. Sometimes you may feel like you need an advanced degree in horticulture to succeed in keeping a garden.
Over the past few years, we have seen some of the driest years followed immediately by some of the wettest years on record and this has left our plants and urban forest stressed and looking for a reprieve. We as diligent gardeners take it upon ourselves to help balance out the water needs of our plants, but sometimes we do more harm than good.
Often I see a homeowner, with all the best intentions, watering their plants when the soil is already heavily saturated and the plant is beginning to drown. This happens frequently because plants only have one way of showing issues with soil moisture and that is through wilting which is a universal sign to many of drought stress. Overwatering can frequently cause root rot diseases which decay fine root hairs that actually do the heavy lifting of water uptake.
When these root hairs are damaged by root rot organisms, the plant can be surrounded by water but very little is available so the plant shows signs of drought and our first inclination is to add more water to the soil. This then furthers the disease cycle, allowing the root rot to flourish, limiting water uptake by roots, and the feeling that more water is needed, creating a feedback loop that only ends when the plant dies. Another place this can be seen is in areas with poor drainage or locations where we channel and direct runoff, such as culverts and downspout outlets.
The best way to avoid overwatering is to get down and dirty with your plants. If you’re watering and haven’t checked the soil to see what the moisture level is like, it’s similar to a doctor prescribing medication without even seeing you. This can create deadly problems. When plants are wilting and show water stress and your soil is already wet or even saturated, watering needs to be slowed down but not completely stopped. This is akin to the plants going cold turkey which, will almost immediately kill them as they can no longer mine for water due to root loss. A slow drawback on watering is the solution. It allows the plants to slowly acclimate and regrow roots as the root rot diseases reduce.
The best “rule of thumb” for watering is deep and infrequent (or my favorite: the “rule of pinky”). If irrigation is used, infrequent but deep soakings keeps plants hardier as they still get the water they need but have to work for the water in between watering. If watering is needed on individual plants and a hose is used at the base of the plant, a flow of water the diameter of your pinky for an hour or so is great to keep the soil moist deep into the root zone. This should be performed once a week during normal conditions and at least twice weekly during drought conditions. The use of a GatorBag can also eliminate the need to constantly check and remember to water the tree.
Be mindful that water can be a double-edged sword. It is essential for the health and growth of your plants, but too much of a good thing can be just as bad or even worse than not enough. Be water-wise when providing for your landscape and take a minute or two before turning on the water to make sure that your plants actually need it.
Spring brings out all of the bugs, and while most of the ones we think about are damaging or annoying, there are thousands that go about their life nearly out of sight and out of mind. Every once in a while, one of these thousands can be pretty enough, large enough, or odd enough to catch our attention as we rush through our own lives. The jumping oak gall wasp is just such an insect. You can see it on many of Virginia’s oaks this time of year, and it might just warrant a pause in your day to see something unique and new.
The jumping oak gall wasp will almost exclusively damage mature white oaks (and other oaks in that family) around home landscapes. In most cases, tree owners never notice the insects or the galls they create on the white oak leaves, as they are tiny and non-damaging until the population hits a level that the tree cannot sustain. When this occurs, the young leaves will brown and prematurely fall causing stress to the tree. The real reason that jumping oak gall wasp is of interest is because of the jumping action that gives it the title.
The galls are actually tiny vegetative growths made by the tree’s leaves. They act as shelter and a food source for the larvae of a small stingless wasp where the insect spends most of its life. The gall wasps fall from the trees in late spring and will do a little dance on the ground to lodge themselves into cracks and crevices to wait out the rest of the year before they emerge as adults the following spring, when they start the lifecycle again. (Click here to see the jumping gall wasp in action.) If you have a white oak in your landscape, you can likely see this occurring on your sidewalks and driveways right now. This movement is caused by the larvae moving inside the dry gall much the same way “Mexican Jumping Beans” work.
As white oaks begin to leaf out in the spring, the adults hatch from the overwintered galls and begin the cycle again by laying eggs on newly emerging leaves when they are extremely small and still expanding. The eggs produce hormones that hijack the normal leaf growth and make the leaves grow fleshy tissue around the developing eggs. As the eggs hatch, the larvae begin to feed on the gall and grow. In heavy infestations, extensive foliage damage occurs and the oaks will drop the damaged leaves in an attempt to protect themselves from further injury, while light to moderate infestations go unnoticed. In some cases, it can warrant supplemental watering, mulching, and soil amendments to help reduce the stress caused by the leaf drop but preventative treatment is not recommended as it is very hard to time properly and requires very large applications of broad-spectrum insecticides that can damage non-target insects and invertebrates.
If you have white oaks on your property, it is likely that you have seen what looks like very tiny orange to tan dots all over your car, driveway, sidewalk, and landscape plants. These dots are about the size of the head of a pin and are extremely easy to overlook, but will hopefully now your eye will know what to look for. Take a minute or two to walk your landscape and see if you can detect the telltale jumping of this little wasp as it goes through its life underfoot and nearly out of sight.
It’s that time of year when you might find yourself admiring the trees along the highway covered in cascades of purple flowers. If you’re left wondering what type of tree that may be and why you never noticed it before, it might surprise you that it could be anything from an oak to a pine covered in those beautiful flowers. What you are seeing is not the tree but, actually, the plant that is slowly killing it. Let me introduce you to my favorite plant to hate — Wisteria.
My distaste for Wisteria does not spread across the genus but only falls on the two Asiatic species, Wisteria sinensis and Wisteria floribunda, which are both non-native, introduced species that have become exceptionally invasive in the urban forests of the Mid-Atlantic. This flowering vine will establish itself quickly in nearly any garden and begins climbing anything it can reach. Once fully established it will begin its spread through both seeds and above-ground stolons. A small trellis of Wisteria beside a deck or patio can quickly turn into a backyard filled with vines and nearby trees being overwhelmed. As the vines grow they climb as high as possible to seek out sun and will climb to the top of 50- to 70-foot tall trees, the whole time growing in diameter and slowly choking the tree. Heavy infestations can choke out entire trees and even woodlots. But what to do if it has already started its invasion of your property?
Control can be a tedious and sometimes hard-fought battle that may need a lot of elbow grease, herbicides, and even professional help. Smaller plants and clumps can be culled by simple hand pulling with a watchful eye for additional sprouts popping up. Larger infestations may require chainsaws, herbicides, and even the ever-popular goat to get things under control. It may take several years of repeated treatments to full eliminate the vines.
One final tidbit to note is that while goats can eat modest amounts of the plant, Wisteria should definitely be kept away from children or curious pets as the smooth and sizable seeds are very poisonous. And the rest of the plant poses a smaller threat, but still a threat if eaten. This does not mean that Wisteria doesn’t have a place in our landscapes and urban forests. It is indeed a beautiful plant that adds a splash of color in the spring. The native version of the plant, Wisteria frutescens, will still give you the showy flowers and some climbing without the nearly uncontrollable spread. It is also very well suited to remaining a small clumping shrub without support for climbing. If you can’t find this species in your local nursery, ask for it by name, which may help them to decide to stop carrying the Asiatic species.