Pests and Diseases: Glyphosate Damage to Trees


Today’s Pest and Disease post is a little different than some of the other topics that we’ve looked at such as gloomy scale or aphids. Today we are going to look at something that you may not even think of when you’re spraying weeds in your garden: glyphosate damage to trees. In case you’re not up on your chemical names, glyphosate is the active ingredient in products like Roundup and RazorPro. We have been told for years that glyphosate is biodegradable and has no residual impact on the soil that it touches. More and more, people are beginning to realize that may not be the case.

glyphosate damage to trees

Photo courtesy of Ohio State University

Dr. Hannah Mathers of Ohio State University has led the research on determining if glyphosate is responsible for cankers on trees where the chemical has been applied. The cankers resemble frost cracks that can occur during cold temperature extremes. The difference is that frost cracks generally appear on the south side of the tree whereas “glyphosate cankers” can occur on any side of the tree. The long and short of her research is that glyphosate is accumulating in the phloem of the trees and causing cankers and ultimately death. The death is a slow one as microorganisms move into the canker and set up shop. Glyphosate may not be the cause of death in the end but it is what allows the microorganisms a chance to kill the tree.

So how does the glyphosate end up in the phloem of the tree? It generally occurs one of two ways: the first way is by applying the herbicide around the base of the tree and having it come into contact with the trunk. You may not be trying to spray the trunk directly but if there are weeds at the base of the tree, you may inadvertently spray the trunk. The second way is through killing the weeds that grow within the root zone of the tree. That is, after all, probably why you are spraying herbicides to begin with. When these weeds die, they exude a small amount of the chemical into the soil which can then come into contact with the roots of the trees. The roots take up the small amount of glyphosate into the xylem of the tree but as it is transported throughout the tree, it ends up being stored in the phloem. Research indicates that the glyphosate can build up in the phloem for years and continue to cause problems for the tree for a long period of time.

Dr. Hannah Mathers has found that using glyphosate products that contain a surfactant exacerbates the problem. Surfactants are added to many pesticides to allow the chemical to “stick” to the target pest. The stickiness that results also allows the glyphosate to adhere to the trees if they are inadvertently sprayed. Unfortunately, virtually all of the homeowner versions of glyphosate contain surfactants.

So what can you do to avoid glyphosate damage to trees? MULCH! While I certainly don’t advocate the practice of mulch volcanoes, a 3″-4″ layer of mulch under your trees will keep most of your weed problems at bay. For the weeds that appear, hand weeding is going to be your best option. Also, consider planting perennials under the trees. A groundcover of plumbago (Ceratostigma plumbaginoides) will thrive in sun or shade and will form a dense mat that is almost impenetrable to weeds. If you don’t have to have the perfectly manicured garden, consider planting a nitrogen fixing plant under your trees so that the trees have a free source of nitrogen. Examples include members of the legume family such as peas and beans, alfalfa and clover.

I hope that you’ve gleaned a bit of useful information from today’s post. Take a look around your yard and other landscapes to see if you spot any of the “glyphosate cankers”. Let me know what you find by leaving me a comment below or sending me an e-mail at Happy gardening!

March 13, 2012Permalink 2 Comments

Plant Profile: Early Spring Blooming Trees and Shrubs


Today I thought that we would take a look at some of the early spring blooming trees and shrubs. They are everywhere now and they’re such a delightful welcome after winter.

FLOWERING ALMOND (Prunus glandulosa)

 early spring blooming trees


SAUCER MAGNOLIA (Magnolia soulangiana)

Early spring blooming trees and shrubs


STAR MAGNOLIA (Magnolia stellata)

early spring blooming trees and shrubs


FORSYTHIA (Forsythia x intermedia)

early spring blooming trees and shrubs


FLOWERING QUINCE (Chaenomeles ‘Jet Trail’)

early spring blooming trees and shrubs


KWANZAN CHERRY (Prunus serrulata)

early spring flowering trees and shrubs

All of the early spring flowering trees and shrubs that we looked at today are blooming now in the Richmond, VA area. Well, all except the Kwanzan Cherry. I just wanted to add that one because it’s so beautiful when viewed up close. It makes quite a show while driving 45 miles per hour but if you have the opportunity to view the flowers at close range, you’ll be amazed by all of its beauty. The Saucer Magnolia flowers are no more as they were taken out by a freeze. Be sure to check out this post for more information on how to properly site a Magnolia soulangiana. And I know that Forysthia are planted ad nauseum but if they are allowed to grow into their natural form instead of being pruned into little meatballs, they are a beautiful shrub. OK Mid-Atlantic Gardening readers, what’s blooming in your area right now? Leave me a comment below or e-mail me at Happy gardening!

Pests and Diseases: Hemlock Woolly Adelgid


Today’s Pest and Disease topic is the Hemlock Woolly Adelgid. Unless you are familiar with them, you may not be sure if it’s a fungus or an insect. Hemlock Woolly Adelgids are little white fluff balls that attack one of our most beautiful native evergreens, the Eastern Hemlock (Tsuga canadensis). Let’s look at how this insect came to be one of the most dreaded of all pests in the eastern forests.

Hemlock Woolly Adelgid was accidentally introduced to the United States in the early 20th century but it wasn’t until the middle of the 1900’s that it became a true pest. It found its way to the Eastern Hemlock and fell in love…it starting having lots of babies and without a predator to keep its population in check, it became a force to reckon with. It’s depressing to know that the Hemlock Woolly Adelgid is responsible for the death of Eastern Hemlocks and studies have estimated that it could wipe out the hemlocks in some southern areas within 10 years.

hemlock woolly adelgidLet’s look at how a small, little fluff ball can wreak so much havoc. The Hemlock Woolly Adelgid literally sucks the life out the trees and the trees are so weakened by the damage that they succumb to starvation. It doesn’t happen overnight…that would be too easy. It usually takes years to kill the trees and in those years, the population of the adelgids continue to climb and they just move right on over to the next tree to begin their devastation again.

While hemlock is a common sight in northern U.S. forests, its presence is mostly in the mountainous areas of Virginia and Maryland where it enjoys the cooler temperatures. In fact, I remember a story from my Woodies professor at Virginia Tech where a student had been on a hike up to the popular Cascades waterfall. The student came back excited to tell Dr. Niemeira that he found a variegated hemlock. Unfortunately, the “variegation” ended up being a heavy infestation of Hemlock Woolly Adelgid.

So what can you do if you have Eastern Hemlocks? Scout regularly for the pest. Be sure to check the undersides of the foliage as this is a favorite hiding spot. I don’t like to just pass you off to someone else, but if you spot the little fluff balls on your hemlocks, I recommend that you consult a Certified Arborist. They will be up-to-date on the latest recommendations for controlling them and they will probably be able to apply the insecticides for you. While I’m not a fan of pesticides, if you have to use them let someone who has been certified in the application process do the work for you. I need to hear from the Mid-Atlantic Gardening readers if you have encountered Hemlock Woolly Adelgid. Leave me a comment below or e-mail me at Happy gardening!

Plant Profile: China Fir (Cunninghamia lanceolata)


Today’s Plant Profile is about the China Fir, or Cunninghamia lanceolata. This is a majestic, evergreen tree that stands out in the landscape with its blue needled foliage. It is not a tree that should be planted in a small area as it can reach 75′ tall by 30′ wide in the landscape. It should be sited in full sun or very light shade and so that it can spread its branches far and wide.

China FirChina Fir was brought to the United States in the 1800’s for use as an ornamental tree. As is indicated by its common name, it hails from China where it can be found growing on roadsides as well as rocky hillsides. This should give you some indication of the toughness of this tree. It will do its very best in moist, well-drained soil but will grow quite well in soil that is drier. It is reliably hardy to Zone 7 but can be grown in Zone 6 gardens as well. In a cold Zone 6 garden, it may be killed to the ground in a harsh winter but it will resprout from suckers and will form a lovely dense shrub until the top is killed again in a subsequent winter. China Fir and Yews are the only two conifers that will resprout from suckers if they are cut back to the ground. You can use this knowledge to your advantage if you have a smaller garden but still want the beauty of the China Fir; just cut it back to the ground when it outgrows its allotted space and wait for it to fill the space again.

China Fir does have one significant drawback: it holds its dead foliage scraps in the tree instead of dropping them like pines and other conifers do. I call them foliage scraps because they aren’t individual needles…they are foot long pieces of foliage that have the needles intact. If allowed to accumulate for too long, the tree can look quite unkempt in the landscape. I have found that if you limb the tree up, it provides a path for the dead foliage to exit the tree. It also allows the lovely cinnamon colored bark to be displayed.

China FirIf you enjoy blue foliage in the garden, you should consider the China Fir. ‘Glauca’ is a cultivar that has been selected for its rich blue needle color. If your garden is small, you can treat it like a large shrub and cut it back every few years to keep it in check. But the true beauty of the China Fir is observed when it is allowed to grow to its maximum ability and spread its long Dr. Seuss-like branches over the landscape. I’d like to know if any of the Mid-Atlantic Gardening readers have experience with growing China Fir. Leave me a comment below or e-mail me at Happy gardening!

February 22, 2012Permalink 13 Comments

Plant Profile: American Beech (Fagus grandifolia)


American Beech

Today’s post was inspired by glancing in the woods behind my house. Everywhere I looked I saw the light tan colored leaves of the American Beech tree (Nancy Ross Hugo describes the color as palomino, like that of a horse). I saw them on the way to work and on the way home…they seemed to be everywhere in the woods around Richmond. When all of the other trees in the woods have their leaves, the American Beech tree (Fagus grandifolia) can go virtually unnoticed. But in the winter when all of the other deciduous trees stand there looking so barren, the American Beech tree shines with its palomino colored leaves.

Generally speaking, I am not a fan of brown leaves. They send out the impression that something has gone awry in the garden, that someone forgot to water. Pin oaks tend to hold their leaves in the winter too but the leaves of the pin oak look just like the ones that fall in your garden…brown and dead. There is something about the American Beech’s leaves that are inviting. They are light tan in color and invite your eye to keep searching through the woods for more. I think that it is in the winter time that the American Beech is a standout. Unless…

If you are blessed enough to have a large American Beech on your property, consider yourself a lucky gardener. While it may be true that very few plants will grow well under the canopy of an American Beech, it is still quite an honor to be in the presence of a large, established specimen. As the American Beech trees age, they lose their ability to retain their leaves in the winter but what you gain in beauty through the tree offsets the difference. A large 50′-80′ established tree is a beauty in and of itself. The smooth, gray bark is distinct and quite noticeable, even when the garden is alive with other flowering trees and shrubs.

American Beech is native to the east coast and all of the Mid-Atlantic gardening region. It is hardy to Zone 3 and thrives in all but the wettest soils. It can be hard to transplant, which is another reason you should feel blessed if you have a large beech in your garden. The leaves have distinct ribbing and are a rich green during the growing season. They turn yellow in the fall and can light up a garden. Around the same time that the leaves fall, the American Beech releases beechnuts, which are its triangular seed pods that are edible.

American BeechIf you are thinking of planting an American Beech, site it in full sun and plant it in an area that can be enjoyed by your grandchildren. American Beech is a slow growing shade tree that needs plenty of room to grow. There is a quote by Nelson Henderson that says “the true meaning of life is to plant a tree, under whose shade you do not expect to sit.” While you may be able to enjoy an American Beech’s shade, it is your grandchildren who will marvel at its beauty. If you are blessed enough to have a large American Beech, please share the photos with other Mid-Atlantic Gardening readers by sending me an e-mail at Happy gardening!


February 15, 2012Permalink 4 Comments

Pests and Diseases: Crape Murder


While crape murder may not seem like a typical post for Pests and Diseases, it shows who can be the biggest pest to landscapes sometimes: people. People are the ones that decide to whack off the top third of a tree so that it blooms more.

Before I prattle on about the horrific practice of crape murder, let me accurately describe what it is and what it isn’t. If you are a neat gardener that doesn’t enjoy the winter appearance of the crape myrtle seed pods and remove them, you are not a crape murderer. If you remove broken or crossing branches from a crape myrtle, you are not a crape murderer. But if you do this:

crape murder

you are a crape murderer and I implore you to stop! I’m not sure why people think that removing a third (or more in extreme cases) of a tree is a good practice. I understand why “landscapers” do it and the answer is three fold:

  1. It’s easier to prune a tree by making a few large cuts than it is to prune correctly. You can murder a tree in about 5 minutes versus the 45 minutes to an hour it takes to prune a tree correctly to remove broken, dead or crossing branches. While the landscaper can charge the customer more for their time, few commercial customers are willing to pay.
  2. It gives an “added value” service to the customer. Again, the customer may not be willing to pay an hour per tree for pruning, but the landscaper can charge a few dollars more and the customer sees that something has been done. If the landscaper is already there applying mulch, it doesn’t take too much extra time to murder a few dozen trees.
  3. Because other landscapers are doing it. I’d like to find the person who started this trend and figure out their logic. Unfortunately, so many “landscapers” are not trained in horticulture and don’t understand the “why” of doing things, only the “how”. They see others doing it and they follow suit, to the detriment of the trees.


If you have been guilty of butchering your crape myrtles, take solace in knowing that many other folks do it too just because they don’t know how bad it is. It’s same thing that happens with mulch volcanoes…people see the landscaper down the street do it so they think it must be the right thing to do.


The first reason is that it’s plain ugly. Crape myrtles have beautiful structure and exfoliating bark that is really only seen during the winter. The silhouette of a crape myrtle in the winter can be the centerpiece of your garden instead of resembling something that your guests hang their coats on.

The second reason is that by making such drastic cuts, epicormic buds are forced to break. These buds lie dormant and the only time that they break is when the plant is put under undue stress. These buds are weakly attached to the stems and their resulting branches are easily broken during wind or ice storms. Also, the sheer number of buds is unsightly and results in a lollipop appearance where there is a huge ball of foliage sitting on top of a stick that is the trunk of the tree.

Another reason is that it’s just not natural. When will we learn that if you leave nature alone, it is capable of amazing things? Sure there are plants that need to be pruned judiciously like hedges (I don’t like them either by the way – too much work!) but a crape myrtle, in Zone 7, is a TREE! It’s not a plant that is supposed to be reduced in size by a third or more each year for the sake of a few more blooms. To me, it’s the same thing as pruning beautiful forsythia shrubs into little meatballs. What’s the point? A forsythia in its natural form, with its long arching branches, is a beauty to behold. And so is the crape myrtle when it is allowed to grow in its natural state with only corrective pruning. Let me know how often you see crape murder in your area by leaving me a comment below or sending me an e-mail to Happy Mid-Atlantic gardening!

February 14, 2012Permalink Leave a comment

Friday Free For All: Certified Arborists vs Tree Trimmers

certified arborist


In today’s post, I thought that we would look at the differences between Certified Arborists and tree trimmers. Quite often, tree trimmers are just as knowledgeable as Certified Arborists, they just haven’t gone through the effort of becoming a Certified Arborist. Unfortunately, that’s not always true and once a tree is improperly pruned, it generally can’t be “undone”. With that it mind, let’s look at some of the differences between Certified Arborists and tree trimmers:

  1. Certified Arborists have taken the initiative to be certified through the International Society of Arboriculture, or the ISA for short. The test that they must take has been described as “one of the hardest tests I’ve ever sat through” by a co-worker. It requires a great deal of knowledge and years of experience, even to be eligible to sit for the test.
  2. As a condition of their certification, Certified Arborists must agree to continuing their education through classes and seminars. As in all disciplines, arboriculture is an everchanging field where advances are being made and research is being conducted. With a Certified Arborist, you can be sure that they are up-to-date on the latest information.
  3. While you may not need a Certified Arborist to drop a tree in your yard, you would be highly advised to seek one out if you have a historic or otherwise meaningful tree that you wish to keep healthy.
  4. A Certified Arborist will NEVER top your trees. A knowledgeable tree trimmer would never do it either, so if someone recommends it, you know to scratch them off the list of potential contractors immediately.
  5. Investing time and money in a Certified Arborist to care for your trees is an investment that can pay dividends. Having healthy, attractive trees on your property will raise your property value, whereas having poorly cared for or improperly pruned trees poses a significant liability to your pocketbook.


If your trees are in need of care by a professional, I hope that you will consider contacting an ISA Certified Arborist. You can use this link to find local arborists in your area. While their prices will undoubtedly be higher than that of a tree trimmer, the long term payoff to your trees and property value will more than compensate for the difference. Let me know your thoughts by leaving me a comment below or sending me an e-mail at Happy Mid-Atlantic gardening!

February 11, 2012Permalink Leave a comment

Pests and Diseases: Thousand Cankers Disease


I must warn you that today’s post is a bit depressing. If you enjoy the beauty of walnut trees (Juglans nigra) and the delicious nuts that they produce, you may be a little sad after learning of the latest disease that is infecting these beautiful native trees.

Thousand Cankers DiseaseThousand Cankers Disease is caused by a fungus, Geosmithia morbida, that is brought into the phloem of the tree by the walnut twig beetle. Essentially, the fungus catches a ride on the beetle and is thereby introduced to the tree. The subsequent individual canker that is produced by the tree isn’t especially large, but there can be 35 cankers in a square inch of wood. These smaller cankers coalesce and turn into larger cankers that ultimately kill the tree. The trees essentially die of starvation as the phloem tissue is prevented from delivering the carbohydrates that are produced through photosynthesis to other areas of the tree where they are needed.

The walnut twig beetles like to feed on young, tender new stems and it is virtually impossible for the average homeowner to scale a large walnut tree to have a look. The beetles move south in the tree to the lower trunk tissue during the winter; it may be possible to observe some of the cankers and/or entry points at that time.


Thousand Cankers DiseaseThe first clue that your walnut tree may be infected with Thousand Cankers Disease is branch dieback. As the leaves and branches are starved of nutrients, the tree’s self-preservation mechanism is to eliminate the area that isn’t receiving the “food” that is needed. The individual beetle entry points are small so they can easily go unnoticed. The cankers sometime weep sap and this is a dead giveaway that your trees are infected.

How does the old saying go: “the best defense is a strong offense”? If you currently have black walnuts on your property, make sure that they are not stressed by competition with turf and other plants. Mulch them well and supplement their water during times of drought. As with most insects, the walnut twig beetle will seek out the weakest trees first so anything that you can do to keep your trees thriving instead of just surviving is a plus.


Unfortunately, not much can be done to save the trees once they are infected. In theory, systemic insecticides can be applied to the tree to lessen the activity of the beetles. If you suspect that your trees may be infected with Thousand Cankers Disease, I would seek the council of your local Extension Agent or an ISA Certified Arborist. If there is any saving grace to this disease, it is that the fungus is not translocated in the vascular tissue like Dutch Elm Disease.

It’s an unfortunate reality that Thousand Cankers Disease has already been identified in Virginia and Pennsylvania. I’m sure that as time goes on, this disease will continue to spread in the Mid-Atlantic gardening states. Let me know if you have any experience with Thousand Cankers Disease by leaving me a comment below or e-mailing me at Happy gardening!


February 7, 2012Permalink 3 Comments

Reader Question: Saucer Magnolia


Today’s reader question comes from Anthony in Williamsburg, VA:

I really like Saucer Magnolias but it seems that almost every year their blooms are killed by a spring freeze. I’d like to plant one in my yard but I’m wondering if there’s anything that I can do to prevent the blooms from being killed. Thanks.

Magnolia soulangianaAnthony, this is a timely topic as the Saucer Magnolias (Magnolia x soulangiana) in the Richmond, VA area are in heavy bud now. If the weather continues to be warm, they could be in full bloom in a few weeks. Given that Punxsutawney Phil saw his shadow today and we have 6 more weeks of winter to endure, that may not be a good thing. I can sympathize with your concern over having a spring freeze ruin the beautiful blooms…for 8 years I watched a beautiful Saucer Magnolia’s blooms turn to mush until finally in the ninth year, they were able to make it through spring without a freeze.

There are several actions that you can take BEFORE you plant a Saucer Magnolia at your house to ensure that the blooms are enjoyed instead of mourned over.

  1. Plant the tree so that it has a northern orientation. Areas that face north are generally cooler which may sound counterintuitive, but it is the spring warmth that forces the trees to bloom. If you can keep the tree cooler so that it doesn’t realize the temperatures are as warm as they really are, you may be able to postpone blooming for a week or so which may be just enough time to eek past a few freezing nights.
  2. If you have a slope in your yard, plant at the top of the hill to avoid frost pockets. I’m not sure if you are aware, but colder air will flow downhill on a slope and if there is anything at the bottom to trap the air, the colder air will settle there and you end up with a frost pocket. The few degree difference can be just enough to cause your blooms to turn from beauty to beast.
  3. Try planting one of the later blooming cultivars. ‘Speciosa’ is a white flowered variety that blooms later and ‘Verbanica’ is a late blooming pink selection that maxes out at around 10′ tall.


Anthony, I hope that I’ve given you some things to consider when planting your Saucer Magnolia. Please realize that even by taking all of these precautions, there will be some springs where the blooms get zapped. If you know that the freeze is coming, cut some of the blooms and put them in a vase where you can still enjoy them indoors. If any of the other Mid-Atlantic Gardening readers have suggestions for Anthony, leave them in the comment section below or e-mail me at Happy gardening!


February 2, 2012Permalink 1 Comment

Plant Profile: Red Twig Dogwood (Cornus sericea ‘Baileyi’)


Before we get into our topic today, I want to remind you that our seed give away is this Friday, February 3. To enter, all you have to do is enter your e-mail address in the box to the right. That’s it…no catches or surprises. Of course, I would never sell your e-mail or anything like that; I’m here to help you with your gardening questions, not compromise your trust.

Cornus sericea 'Baileyi'Red Twig Dogwood…you may not recognize the name immediately but if you’ve ever seen this plant glowing in the winter landscape, chances are that it is etched in your memory. This dogwood, Cornus sericea ‘Baileyi’, isn’t what you think of when you hear the word “dogwood”. No, instead it is a shrub that is grown for its striking red stems.

In the winter landscape, Red Twig Dogwood is a standout, especially when grown against a light colored background or when displayed in a snowy landscape. It grows to around 6′ to 8′ tall and is equally as wide. It flourishes in dry soils once established but can also tolerate soil that tends to be slower draining which makes it perfect for that low area of your garden. In summer, it has the appearance of just another green shrub after its white blooms disappear in May. The flowers give way to beautiful porcelain blue berries that are adored by birds. When the days begin to shorten and the temperatures begin to fall, beautiful tones of red and purple are displayed before the leaves drop. Red Twig Dogwood is hardy from Zones 3-8 which makes it a shoo-in for Mid-Atlantic gardening enthusiasts.

Maintenance of Cornus sericea ‘Baileyi’ is minimal once established. There are two schools of thought for pruning to enhance the red coloration of the stems. The first method of pruning is to remove 1/3 of the shrub each spring to eliminate the oldest branches as it is the newer stems that display the best coloration. The next method is the one I prefer as I consider myself a lazy gardener. Going the lazy route involves rejuvenating the entire shrub every 3 years or so by removing all of the branches to within 8″ of the ground. The flush of growth that ensues will be a blazing fiery red…of course you won’t really see it until the following fall when the leaves drop but you will be rewarded with a beautiful show.

I would be remiss to not mention the cousin of the Red Twig Dogwood, the Yellow Twig Dogwood. The latin name of the yellow version is Cornus sericea ‘Flaviramea’ and the growth habit and care is the same with the exception that Yellow Twig Dogwood tends to form colonies through its suckering habit. Let me know your experience with Red Twig Dogwood by leaving me a comment below or e-mailing me at stacey@midatlanticgardening. Happy gardening!

February 1, 2012Permalink 1 Comment