Just across Maryland’s border, millions of people flock to Washington, DC at this time of year to witness the spectacular display of 3,000+ cherry trees in bloom around the Tidal Basin. Keeping these famous trees healthy from pests, predicting the timing of peak bloom, and mitigating the threat of rising tides from climate change are among the challenges that need to be addressed to keep these cherished plants in top form for people to enjoy now and for many years to come.
Dr. Lauren Schmitt, an ecologist working with the Burghardt lab in the University of Maryland’s Entomology Department, gives us a close look at the history of these magnificent trees, how pests are managed using an Integrated Pest Management (IPM) approach, how peak bloom times are predicted, and how some of the non-pest threats such as soil compaction and flooding are being addressed.
Read her two part-series on DC’s Famous Cherry Trees:
Lauren Schmitt, Ph.D. is an ecologist working at the intersection of ecosystem ecology and community ecology. A member of the University of Maryland Burghardt Lab, her research focuses on linking biodiversity and ecosystem function. Much of her work takes place in a forest diversity experiment, “BiodiversiTREE” to assess how tree diversity shapes communities and ecosystem processes.
Chad Hanson, a University of California-Davis researcher and Sierra Club board member observes, “We are trapped by an outdated cultural idea that a healthy forest is one with nothing but green trees. An ecologically healthy forest has dead trees, broken tops, and down logs.”
Over the last several years, you may have noticed an increase in dead and dying trees in our watershed, particularly oaks. There are a number of factors at play, including soil compaction from development, old trunk wounds, storm damage, environmental stressors such as heat and drought, opportunistic diseases and insects, and just plain old age. If you think the only response to a dead tree is to cut it down, think again!
It has been estimated that dead trees, called snags when they are still upright, and trees with decaying wood provide important habitat for about 25 percent of the forest wildlife species in the northeastern United States. Add aquatic species and that number climbs even higher.
Did you know that more than eighty birds in North America are cavity-nesters, include 10 species of owls, 7 ducks, 2 falcons, all 21 woodpeckers, and about 40 songbirds? They raise their young in hollowed out sections of dead and dying trees. In addition to providing a place for birds to nest, cavities also protect birds from predators and offer shelter from the elements. Dead branches serve as a perch from which birds can survey their surroundings, hunt, eat, and dry their wings and rest. If that weren’t enough, a dead tree offers a smorgasbord to insect-eating birds and other animals, with holes, depressions and cracks that double as places to store seeds, nuts and other food.
Logs on the ground also provide a bounty of food and shelter for a range of critters. Hollow logs provide cover and protection for small mammals like foxes, rabbits, skunks and raccoons. The wood itself may be home to ants, beetles, and carpenter bees that tunnel into it, while bark beetles build extensive chambers under the bark. These insect residents are, in turn, a good source of protein for turtles, toads and lizards. No walk in the woods is complete without flipping over a log to see what lies beneath –
beetles, worms, centipedes and, if you’re lucky, a salamander. Don’t forget to roll the log back over gently, lest you destroy someone’s happy home. Continue reading →
Late-winter through mid-spring and early through mid-fall are the best times to plant woody ornamentals, so this is a good time of year to start planning your process if you are interested in adding shrubs or trees to your landscape this year.
As Watershed Specialists, we spend a lot of time helping people decide which species of trees might be best for a particular project based on a variety of factors including
sun, soils, and size. Every now and then, people will also see if they can add their favorite tree to the project. Now the number of reasons why people like a particular tree is
probably rivaled by the number of grains of sand on the beach and there’s not enough room in this article to list them all. But this got me to thinking; we spend so much
time talking to other people about trees, I wonder what our favorite ones are? Well, below is the answer to that very question. And after reading this, drop any one of us an email and let us know what your favorite tree is and why.
Amanda – Paw Paw (Asimina triloba)
As an eastern North American native species, not only does Paw Paw have a very distinctive flower, it produces one of the largest edible fruits of all our native trees. The main reason this is Amanda’s choice of favorite native tree is that her son loves the fruit! And because of recent interest in Paw Paw fruit, it has earned the nickname Hipster Banana.
Jackie – Red Maple (Acer rubrum)
Red Maples live up to their name: they give us that first shimmer of red in early spring with its flowers and seeds and wraps up the year with fiery red leaves in the fall. Even
though its nickname is Swamp Maple, Jackie appreciates Red Maples not only for their color, she’s actually made syrup from its sap!
Kelsey – Willow Oak (Quercus phellos)
A tree she grew up with in her home state of Michigan, Kelsey’s favorite is the Willow Oak. This fast-growing species produces plenty of acorns which keeps the squirrels busy, it also casts a great shadow on her apartment, something she appreciates during the summer months.
Jennifer – Tulip Poplar (Liriodendron tulipifera)
Earning its name from a coffee-cup sized flower that people don’t often see since they’re so high up in the tree, the Tulip Poplar is Jen’s favorite. This tall growing tree is important to a number of birds and butterflies. And its cat-shaped leaf reminds her of the two felines that are really in charge of her house.
Eric – Black Gum (Nyssa sylvatica)
My fave is the Black Gum. I grew to appreciate it over time because of the wide variety of conditions it grows in. And when people tell me they love the red color of a Burning Bush, which can invade natural areas, I often suggest that plants like Black Gum not only have a beautiful red color, they produce flowers and fruit that are beneficial to native insects and animals.
This season (2019) the Home and Garden Information Center has received a tremendous number of questions on rapid browning and death of many of our oak trees in urban landscapes and forest situations. Even though it would be convenient to point to a single reason for this dieback it is most likely a combination of weather, disease, and insect factors.
A logical starting place to look for an explanation would be the often-overlooked gradual health decline of our trees due to old age, restricted root zones, soil compaction in work zones, old trunk wounds, storm damage, poor pruning, urban stress such as reflected heat and drought, and opportunistic diseases and insects. These decline factors can extend over many years, leaving trees to try and cope with less than ideal growing conditions.
Last season these conditions were further worsened by the excessive rainfall that continued into this spring which resulted in standing water at many locations that had low spots, compacted soil, or water collection points. Flooded soils and saturated root zones further weakened trees by allowing root pathogens such as Phytophthora a chance to reduce the overall number of healthy roots.
In general, red, black, chestnut and white oaks don’t tolerate poorly drained soils. Trees can tolerate some reduction in root health, as long as temperatures remain cool, water demands aren’t high, and adequate time is allowed for root regeneration. As a root system loses the ability to support the tree’s water needs, dieback will occur especially in the upper branches.
When the high summer temperatures began this season in mid-July and the low rainfall extended into this fall these conditions accelerated the loss of tree vigor and resulted in sudden browning of tree leaves and canopy dieback. Compromised tree health often allows pathogens such Armillaria and Hypoxylon to invade, which further accelerates dieback and death. In addition, opportunistic insects such as Ambrosia Beetles and Two-lined Chestnut Borer, will attack tree trunks and continue tree demise.
There are a few positive steps that may alleviate some tree stress. It is very difficult to reverse decline in stressed oaks so select trees that still have green foliage and irrigate near their bases during this period of high drought stress. Even minimal amounts of water can help recovery and prevent drought stress before winter dormancy. Practices that open up compacted soils to increase drainage and raise soil oxygen levels (e.g., vertical mulching) will often help as well.
As we continue to receive information about dying oaks across the state, we still have many unanswered questions. We will continue to collect data on tree species, age, and pest occurrence, in coordination with other agencies across Maryland.
By Dr. David L. Clement, Principal Agent, University of Maryland Extension, Home & Garden Information Center and Dr. Karen Rane, Director, University of Maryland Plant Diagnostic Laboratory
I knew I had to go back to school to study horticulture when I was in my mid-twenties. Every day on my way to work I found myself looking out the windows at trees instead of watching the road. The Catoctin mountain forest was particularly enticing. Route 15 was a much quieter road then, and fortunately, there were no mobile phones to provide additional distractions. Although I admired the landscape in general, there was one tree that stood out amongst the others: the sycamore. Against a blue daytime sky or a sunrise dancing with pink and purple hues, its white bark was remarkable. The shape of this towering tree with its dazzling bark and color contrast inspired me to leave a secure job in search of knowledge for the things that ignited curiosity in me. Continue reading →
A frequently asked question is what a homeowner can do when a neighbor’s tree has become diseased and poses a danger. The neighbor may be trying to treat the tree to save the tree or might not be able to afford to have the tree taken out correctly by a trained professional. In these cases, courts have found that a residential property owner has a duty to eliminate the danger posed by a diseased tree and prevent the tree from damaging a neighbor’s property. The exception to this would be when a healthy tree causes damage due to an act of God, such as a storm.
Maryland courts have not explicitly dealt with a diseased tree falling on a neighbor’s property. The Court of Special Appeals has dealt with the issue of a motorist injured by a tree limb falling through his windshield. In this case, the motorist was driving through a recently finished subdivision in a natural woodland area of Montgomery County, and the tree limb fell due to the natural decay process. The court highlights that a landowner would need to be aware that the tree was in a deteriorated condition. Urban landowners would have a duty to inspect trees on their properties to determine if trees are dangerous. This duty to investigate would not extend to rural property owners and owners of suburban forests due to the size and number of trees on these tracts of land.
During the inspection, the urban landowner would have to deal with any discovered diseased trees. An urban landowner with a diseased tree would be under a duty to eliminate the danger to prevent the diseased tree from falling or damaging a neighbor’s property. If the urban landowner does not do anything and the tree damages a neighbor’s property, then the urban landowner would face potential legal liability for the damage caused by the falling tree.
Looking at an example, an urban landowner who has a tree with Emerald Ash Borer damage, the landowner would need to either treat the tree and deal with dead limbs that could damage a neighbor’s property or have the tree removed. If the urban landowner fails to do this or the tree continues to decline after the treatments and the landowner fails to do anything, and the tree damages a neighbor’s property, then the urban landowner would be liable to the neighbor for the damages caused by the tree.
One case where a property owner might not see liability from damages caused to a neighbor’s property from a tree would be with an act of God. Acts of God are typically events such as storms, earthquakes, or another events outside of human control. If the tree owner can show the tree fell due to the act of God and not due to disease, then the tree owner will typically not be liable for the damage.
Urban landowners with trees need to take into account that there is a duty to inspect trees in Maryland. Excluded from this duty would be rural landowners and suburban forest landowners. If a diseased tree is found on the property, then the urban landowner would need to either treat the tree or have the tree removed to prevent the tree from damaging neighboring landowners. University of Maryland Extension’s Home & Garden Information Center provides resources, for example, on handling issues such as Emerald Ash Borer and other tree pests and diseases.
Hensley v. Montgomery County, 25 Md.App. 361 (1975).