Got Nature? Blog

Storm damage, trees downSafety first! Stay clear and look for dangerous hanging limbs, broken branches and other failures before beginning cleanup or inspections. Keep others clear of the areas beneath and around damaged trees. Be alert for power lines that could be involved with damaged trees. All utility lines should be considered energized and dangerous.

Lindsey Purcell, Purdue urban forestry specialist, shares, “in my experience, during storm cleanup, many tree owners are faced with the decision of what to do with their trees relative to restoration or removal”.  There are several types of tree damage that occur from violent weather. Each has its own specific assessment considerations. All parts of the tree should be inspected during a post-storm assessment. This requires the expertise of trained, professional arborists to assist with the decision making regarding the best course of action. Unfortunately, there are those who take advantage of the situation and overcharge or provide poor advice when it comes to the best decision on their trees. Don’t make any hasty decisions and be sure you are hiring an International Society of Arboriculture (ISA) Certified Arborist, ask for references and proof of insurance in the process.

View publication Trees and Storms located in The Education Store, Purdue Extension’s resource center, for more information.

Resources:
Trees and Storms – The Education Store, Purdue Education Resource Center
Caring for storm-damaged trees/How to Acidify Soil in the Yard – In the Grow, Purdue Extension
Moist soil and rotten roots makes it easy for trees to come crashing down – Fox 59 News
Why Is My Tree Dying? – The Education Store
Tree Risk Management – The Education Store
Mechanical Damage to Trees: Mowing and Maintenance Equipment – The Education Store

Lindsey Purcell, Urban Forestry Specialist
Purdue University, Department of Forestry and Natural Resources


Dying oak leaves, phytophthora ramorum-Sudden Oak DeathSudden oak death, as the name suggests, is a disease that is capable of rapidly killing certain species of oaks.  It was first identified in California, in 1995. Two years earlier it was identified in Germany and the Netherlands, killing rhododendron. Because the pathogen originally infected and killed tanoaks, an undesirable, understory scrub tree, it generated little interest until other, more desirable oaks species began dying.  However, by this point, the disease was well established and eradication no longer an option, with millions of oak trees killed by the disease.  Currently, over 120 hosts in addition to oaks have been identified, and more continue to be added to this list.  What is most unusual about sudden oak death is the severity of disease symptoms coupled with the broad host range of the pathogen. This leads to difficulty in diagnosing and managing this disease.

What causes this disease?
The pathogen that causes SOD is Phytophthora ramorum (pronounced Fī-toff-thor-ă  ră-mor-ǔm).  This pathogen belongs to a group of organisms in the Kingdom Chromista, and has characteristics similar to fungi, plants and animals.  It spreads throughout the plant by hyphal threads (like fungi), produces spores (like fungi) that have flagella and swim through water (like animals), but its cell wall is made up of cellulose (like plants). When conditions dry up, Phytophthora can produce thick walled sexual spores called oospores, or asexual chlamydospores. Because P. ramorum is not a ‘true’ fungus, many fungicides labeled for control of other fungal diseases are not effective against it.

With such a broad range of plant hosts, it is important to stress that P. ramorum affects different species in different ways. Identification must be confirmed in the laboratory and cannot be identified on field symptoms alone. Many common landscape shrubs are also infected by other endemic Phytophthora species, and symptoms look similar. Boring insects and other root rots may be mistaken for this disease. For this reason, all Phytophthora infections should be screened by the Purdue Plant and Pest Diagnostic Laboratory.

What are the symptoms of SOD?
To understand this disease, it is important to recognize that there are two categories of hosts: bark canker hosts and foliar hosts. Further complicating this is the fact that oaks are divided into three subgroups, and only the red oak group are susceptible to this pathogen. Of our 17 oak species in Indiana, half are potentially, or known to be susceptible, and include black, blackjack, cherrybark, Northern pin, pin, red, scarlet, and Shumard oaks. Diagnostic symptoms of infected red oaks include oozing sap and red-brown cankers that often leading to death.

Our concern right now is on ‘the other’ hosts. Despite its name, sudden oak death primarily spreads through foliar hosts that are sold throughout the United States. Foliar hosts include rhododendrons, azalea, viburnum, lilac, and periwinkle (Vinca minor).

These hosts (and many others) are infected via the leaves and small branches. These infections rarely cause death, and can be mistaken for sunscald, twig canker, and dieback caused by other pathogens, including native Phytophthora species. Although symptoms from these infections are not severe, and are rarely fatal, the infections produce enormous numbers of spores that can infect neighboring, susceptible oaks—and other plant species. For this reason, we are asking people to examine any rhododendrons (or other co-mingled hosts like azalea, viburnum and lilac) purchased this spring from Walmart and Rural King, while the disease may still be controlled and the pathogen contained. Although this disease doesn’t look like much on rhododendron or lilac, its ability to spread to oaks and kill them is what makes it so devastating. These shrubs play a key role in the spread of P. ramorum, acting as a breeding ground for spores (inoculum) that can spread through water, wind-driven rain, plant material, or human activity. Oaks are considered terminal hosts, since the pathogen does not readily spread from intact bark cankers; they become infected only when exposed to spores produced on the leaves and twigs of neighboring plants.

For full article and photos view: Purdue Landscape Report

Other resources:
Sudden Oak Death: a million trees gone and counting, North Central Pest Management Center
Sudden Oak Death, California Oak Mortality Task Force
Sudden Oak Death, Indiana Department of Natural Resources
White Oak, The Education Store, Purdue Extension resource center
Planting Forest Trees and Shrubs in Indiana, The Education Store
Successful Oak and Hickory Regeneration-The Hardwood Ecosystem Experiment: 2006-2016, The Education Store

Janna Beckerman, Professor
Purdue Botany and Plant Pathology


Question: I have noticed that a lot of very mature (> 80 ft) sycamore trees look ill. They don’t seem to have as many leaves, or as large as they usually get and some have already turned brown and died. There are at least 2 in my 5 acres of woods and have noticed the same with other sycamores while driving from Mooresville to Indianapolis. Is there a certain blight/cancker/pest that is damaging sycamores this year?

Answer: I have also noticed that many sycamores appear relatively bare and may have brown or wilted leaves on the stems and littering the ground around the trees. The culprit is sycamore anthracnose, a fungal disease that causes damage and death of leaves as well as stem cankers. Sycamore anthracnose symptoms can be severe when we have cool, moist spring weather at the time of bud-break and leaf emergence , but healthy trees generally recover and put on new leaf area once the environmental conditions that favor the disease change to the warmer, drier conditions of late spring and summer.

Normally, the best management practices for sycamore anthracnose are patience and maintaining good tree health. The disease cycle is dependent on cool, moist spring weather, so it will run its course by late spring or summer when the average temperatures rise. Trees that are repeatedly defoliated could be reduced in vigor and be more susceptible to other problems, so steps to promote good tree health can be used as a preventative measure.

Resources:
Fertilizing Woody Plants – The Education Store, Purdue Extension Resource Center
Diseases of Landscape Plants (leaf diseases) – The Education Store
Sycamore – The Education Store
Hardwood Lumber and Veneer Series – The Education Store
Anthracnose of Shade Trees – Purdue Plant and Pest Diagnostic Laboratory
Purdue Plant Doctor App- Purdue Extension

Lenny Farlee, Sustaining Hardwood Extension Specialist
Purdue University Department of Forestry and Natural Resources


This looks to be shaping up as a tough winter for us and our trees. Lots of snow and ice are predicted for the Hoosier state and this can be a challenge for our trees and shrubs.

After a heavy snowfall, protect your trees and property with these simple tips:

Heavy limbs

Limbs bending from ice loading.

Ice on Trees

Ice accretion on hawthorn branches.

Do not shake limbs to try to remove snow or ice.
When you find your trees are bending or drooping as a result of ice or snow accumulation, your first instinct is probably to shake the branches or knock the weight off with a broom or something similar. This may cause worse damage or actually cause the branch to snap off. Stop right there! Healthy tree branches are flexible, so knocking off the accumulation of snow or ice accretion may cause them to “snap” back, potentially damaging their food and water transport system. The results of the damage may not be evident until next spring.

Trees that tend to suffer the worst damage as a result of snow and ice are upright evergreens, like arborvitae and juniper, and clump trees, like birch. And, when it comes to ice, age does not make a tree stronger; younger trees are better at actually overcoming damage in ice storms.

Hire a Professional.

Snow on Trees

Snow weighing down spruce branches.

Safely remove broken limbs.
Broken and hanging branches can be a threat to people and property. If a limb breaks off from the weight of ice or snow and remains in the tree canopy, have it removed and the remaining stub properly pruned to the branch collar as soon as weather allows. The tree will recover better when properly pruned. For undamaged limbs bending under the weight of ice or snow, don’t prune as a means of correcting the situation. Be patient. It takes time for wood fibers in the limbs to return to its natural position.

Always be mindful of walking or parking under branches loaded down by snow or ice as they may snap and fall, causing injury or damage. If a limb breaks and becomes entangled in power lines, notify your utility company immediately. Never approach a downed power line or a branch touching a utility line.

If there is substantial damage to your tree, have an arborist examine damaged branches and limbs for signs of weakness and injury for reparations. It is best to always hire an ISA Certified Arborist. To find an arborist in your area, visit the website, www.treesaregood.org

How can you help prevent ice damage to trees? Proper pruning is one way. Particularly important is the removal of poor branch attachments and weak branch structure in the tree, prior to winter. For more information on pruning, download the publication, Tree Pruning Essentials.

Full article published in the Purdue Landscape Report.

Resources
Avoid Deadly Risk of Dying Ash Trees with Timely Tree Removal, Got Nature? Purdue Extension-FNR
New Hope for Fighting Ash Borer, Got Nature? Purdue Extension-FNR
Invasive Pest Species: Tools for Staging and Managing EAB in the Urban Forest, Got Nature?
Emerald Ash Borer, Purdue Extension-Entomology
Emerald Ash Borer Cost Calculator – Purdue Extension Entomology
Corrective Pruning for Deciduous Trees, The Education Store, Extension Publications

Lindsey Purcell, Urban Forestry Specialist
Purdue Forestry and Natural Resources


GroundhogGroundhogs are good at many things, said Brian MacGowan, Purdue University Extension wildlife specialist and Forestry and Natural Resources Extension coordinator, but predicting the weather definitely isn’t one of them.

The lore surrounding Groundhog Day originated in Germany where people used the reactions of badgers and hedgehogs to gauge weather patterns. When the tradition eventually migrated to America, Jarred Brooke, Extension wildlife specialist, said hedgehogs, which can be found throughout the United States, became the mammalian forecaster of choice.

“They’re crafty little critters,” McGowan explains, “which is why they’re found in so many different places. They’re habitat generalists and can live in open woodlands, grasslands, what have you.”

While MacGowan and Brooke agreed groundhogs don’t have a great track-record of weather prediction, other facts make groundhogs one of the more interesting members of the squirrel-family.

For full article see: Groundhogs can’t predict the weather but they do poop underground.

Resources:
Selecting a Nuisance Wildlife Control Professional – The Education Store, Purdue Extension Resource Center
Preventing Wildlife Damage – Do You Need a Permit? – The Education Store
The Basics of Managing Wildlife on Agricultural Lands – The Education Store
Nuisance Wildlife – Indiana Department of Natural Resources
Dealing with nuisance geese this spring – Got Nature?
Animal Damage Management: Woodchucks, The Education Store

Brian MacGowan, Wildlife Extension Specialist
Purdue University, Forestry and Natural Resources

Jarred Brooke, Wildlife Extension Specialist
Purdue University, Forestry and Natural Resources


Emerald ash borer (EAB), the most destructive forest pest to enter North America has left hundreds of millions of dead ash trees in its wake.  Although this pest has been found throughout our state, many of Indiana’s ash trees are still alive, or dead and still standing.  Ash trees killed by emerald ash borer, become extremely brittle and break easily as they decline. Branches can fall on people and property in snowstorms, with a light breeze, or even on a calm clear day. Danger could be hanging over your head in the street, in the forest, and even in your backyard.

Why does emerald ash borer make ash trees so brittle?

EAB damaged tree

Large ash limbs that have broken off in the upper canopy.

Unlike elms, oaks, and maples, ash trees use a thin ring of conducting tissue to supply water from the roots to the entire tree.  Emerald ash borer grubs will damage these functional water pipes as they chew just beneath the bark inside trunks and branches. This causes the tree to dry quickly and the structural wood to become prone to cracking. Internal breaks in the structural wood that bear the weight of the tree are often hidden from view by tree bark. As such, limbs can break and fall at any point along the branch at any time. It is not uncommon to have sizable limbs snap 30 feet off the ground on a calm day.

The threat of falling limbs is not limited to just dead ash. A comparative study of ash trees conducted in Ohio shows that structural integrity of ash trees can begin to decline even when trees are mostly green and have two thirds of the canopy still intact.

What should I do to protect myself from falling ash trees and limbs?

EAB tree thinning with percents.

If your tree has lost less than 30% of its canopy hire a professional to protect the tree.

If the tree has lost more than 30% of the canopy, make plans to remove it.  Delaying removal allows the tree to become more brittle and the problem more dangerous.  Remember, EAB causes progressively more injury to ash trees as time goes on.  The dead parts never come back to life.

If you have been treating your tree continue to do so.

How should I remove the tree?

To minimize risk of harm, hire a trained professional who has experience removing emerald ash borer damaged trees. The International Society of Arboriculture maintains a directory of Certified Arborists and their credentials. They can help find an arborist near you.  Always get bids from more than one contractor. Be sure your contractor is insured and bonded in case of an accident. Professionals are happy to share this information.

Some homeowners might be hesitant to remove dead ash trees because they provide valuable habitat for a range of woodland animals and mushrooms. However, we do not recommend keeping them standing unless you can guarantee that no people, domesticated animals, or property will ever be in their path if they fall. If you have a dead tree that can’t be felled right away or ever, stay away from it until after it has fallen.

Article courtesy of the Landscape Report.

Resources:
New Hope for Fighting Ash Borer, Got Nature? Purdue Extension-FNR
Invasive Pest Species: Tools for Staging and Managing EAB in the Urban Forest, Got Nature?
Emerald Ash Borer, Purdue Extension-Entomology
Emerald Ash Borer Cost Calculator – Purdue Extension Entomology

Lindsey Purcell, Urban Forestry Specialist
Purdue Forestry and Natural Resources

Elizabeth Barnes, Exotic Forest Pest Educator
Purdue Entomology

Cliff Sadof, Professor, Ornamental, Pest Management
Purdue Entomology Extension Coordinator


How do I remedy poor branching? Is my tree at risk of splitting, and how can pruning prevent that? Corrective pruning has many implications for tree structure, health, and longevity. Developing a strong, central branch structure in a deciduous tree is critical for preventing structural failure caused by storms, wind, and ice. This 8-page publication explains the problems resulting from a co-dominant stem structure and addresses pruning strategies for correcting poor structure.

To view this full publication please go to Corrective Pruning for Deciduous Trees located in The Education Store, Purdue Extension’s resource center.

Resources
Preparations to Prevent Southwest Tree Injury, Got Nature? Blog
When do you stake a tree?, Got Nature? Blog
Top 5 List for Tree Selection and Planting, Got Nature? Blog
Tree Selection for the “Un-natural” Environment, The Education Store, Purdue Extension
Tree Support Systems, The Education Store, Purdue Extension
Tree Installation: Process and Practices, The Education Store, Purdue Extension
Planting Your Tree Part 1: Choosing Your Tree, video, The Education Store, Purdue Extension

Lindsey Purcell, Urban Forestry Specialist
Purdue Forestry and Natural Resources


Trees with colored leaves.For many people, the autumn season welcomes a pleasurable change in the weather.  We notice, even during a warm fall day, the air gets cooler and the brisk breeze forces out the fleece.  There are a couple of questions to be asked every year at about this time. Why do leaves change color and drop their leaves when fall weather appears?  Much of it has to do with day-length and temperature. The important thing is not that the amount of sunlight has decreased but rather the amount of dark has increased. The plants we’re talking about in this case are the deciduous trees, which are the trees producing the vibrant colors and those that lose their leaves annually. These woody plants “sense” the days are getting shorter during late September as winter slowly creeps in on us. Things like pigment, light, weather conditions; plant species, soil type and location all play important roles in the fall party and colorful confetti trees create for us to enjoy.

When daylight hours are less and temperatures are cooler, photosynthesis slows down and there is less chlorophyll production. This reduction reveals yellow or orange pigment called carotenoids and are usually hidden by the abundance of chlorophyll present in leaves during the growing season.

Unlike chlorophyll and carotenoids, which are present in leaf cells throughout the growing season, anthocyanins are produced mainly in the fall. These natural chemicals give color to familiar fruits such as cranberries, red apples, cherries, and plums. These complex compounds in leaf cells react with excess stored plant sugars and exposure to sunlight creating vivid pink, red, and purple leaves. A mixture of red anthocyanin pigment and beta carotene often results in the bright orange color seen in some leaves.

The cool fall temperatures cause the closing of leaf veins and prevent sugars from moving out which prolongs fall color. Thus a succession of warm sunny days and cool crisp nights can create quite a display.

Soil moisture levels have an impact on the ability to produce good fall color. A prolonged drought can delay color change for a few weeks. The ideal conditions for producing the best colors are good summer weather, with timely rainfall, and sunny fall days with the cool night temperatures.

Tree species vary in their ability to provide fall color, as some trees just don’t produce anything noteworthy. Color depends on the nutrient levels of iron, magnesium, phosphorous, or sodium in the tree.  Some tree species displaying yellow foliage are ash, birch, beech, elm, hickory, poplar, and aspen. Red leaves are seen most often in dogwood, sweet gum, sumac, and tupelo trees. Some oaks and maples present orange leaves while others range in color from red to yellow, depending on the species.

Even with these facts the timing, location, and intensity of autumn color are not completely predictable. To truly experience the colorful display you must be tuned in to your trees and your weather.  Get outside and enjoy the party our woodlands are providing and enjoy nature’s beautiful confetti.

Resources:
It’s Fall, but why are the leaves still green? article and video, WLFI.com
It’s late October and many leaves on trees are still green. What’s up with that?, IndyStar.com
Why Leaves Change Color, The Education Store, Purdue Extension
Why Leaves Change Color, USDA Forest Service, Northeastern Area
Fifty Trees of the Midwest App for the iPhone, The Education Store
Native Trees of the Midwest, The Education Store
Trees and Storms, The Education Store
Tree Installation: Process and Practices, The Education Store

Lindsey Purcell, Urban Forestry Specialist
Purdue Forestry and Natural Resources


Posted on September 7th, 2018 in Forests and Street Trees, Urban Forestry | No Comments »

A recent study at the University of British Columbia noted that a single tree along an urban street can help alleviate winds, shade pedestrians, and decrease wind pressure on nearby buildings. For both homes and businesses, the presence of trees can help decrease costs associated with maintaining indoor temperatures.

flickr.com, photo credit: Kris Arnold

Photo credit: Kris Arnold, flickr.com

Researchers used remote sensing technology to create intricately detailed computer models of a neighborhood that included each tree, garden, and structure. The models were able to elucidate how various scenarios (no trees, bare trees, full-leaf trees) influence airflow, thermal patterns, and overall radiant heating and cooling throughout the streets of the neighborhood. Resultant data indicated trees at various stages can decrease wind speeds by as much as a factor of two. For example, a strong 30km/h wind could be reduced to a comfortable 15km/h breeze.  The results also showed trees reduced the strain caused by wind pressure on building spaced closely together and farther apart. Close examination of the data indicated wind pressure causes up to a third of the costs associated with energy consumption and increased costs up to 10% in winter and 15% in summer. Using data gleaned from over a decade of measurements (from a monitored wind tower), they discovered even leafless trees are beneficial in winter months to regulate air flow and wind pressure on buildings.

This modeling effort represents the first of its kind to simulate actual neighborhood conditions using an existing neighborhood recreated in great detail as a model. Further work of this kind can be used to predict storm effects on structures and pedestrian movement. These data can assist engineers and city planners in the creation and layout of buildings, streets, and greenery while limiting energy losses and help evaluate proposed effects of weather forecasts throughout the neighborhood.

flickr.com, photo credit Rob Young

Photo credit: Rob Young, flickr.com.

References:
M.G. Giometto, A. Christen, P.E. Egli, M.F. Schid, R.T. Tooke, N.C. Coops, M.B. Parlage. 2017. Effects of trees on mean wind, turbulence and momentum exchange within and above a real urban environment. Advances in Water Resources, 106: 154 DOI: 10.1016/j.advwatres.2017.06.018

University of British Columbia. Trees can make or break city weather. Science Daily, 26 July 2017.

Resources:
Tree Selection for the “Un-natural” Environment, The Education Store – Purdue Extension’s resource center
Planting Your Tree Part 1: Choosing Your Tree (Youtube video),  Purdue Extension-FNR
Tree Installation: Process and Practices , The Education Store
Tree Planting Part 2: Planting a Tree (Youtube video), Purdue Extension-FNR
Top 5 List for Tree Selection and Planting, Got Nature?, Purdue Extension-FNR
Indiana’s Urban Woodlots, The Education Store

Shaneka Lawson, USDA Forest Service/HTIRC Research Plant Physiologist/Adjunct Assistant Professor
Purdue University Department of Forestry and Natural Resources


Staked Tree

Figure 1. Properly staked tree adds support.

Stake or not to stake, that is the question!?

“No,” is the likely answer to these common questions about post-planting tree care. Trees establish themselves quite well in normal situations. Support systems such as staking and guying are, in most cases, unnecessary and can even be detrimental. Movement caused by the wind is crucial to help saplings develop into strong, structurally balanced trees.

However, in unusual conditions, staking, guying, or a similar system may be needed to hold tress upright until adequate root growth anchors them firmly in the soil. When necessary, the support system must be installed properly and removed at the appropriate time to prevent damage.

Guyed Tree

Figure 2. Guy wires can provide stability in harsh, windy conditions.

When to Stake Trees

When stakes are needed, timing depends on the environment and the type of tree.

  • Bare-root trees and container-grown trees
  • Large evergreen trees with high wind exposure
  • Open sites exposed to strong winds
  • Taller trees with undersized root balls
  • Trees in areas with high rates of vandalism
  • Threat of mechanical damage

Improperly staked trees suffer from poor development such as decreased truck diameters and smaller root systems – and may be unable to stay upright after you take the supports away. Often trunk tissue suffers from rubbing and may even be girdled by support materials. Also, due to poor development and taper, previously supported trunks are more likely to break off in high winds or blow over after stakes are removed.

Girdling wires

Figure 3. Support materials left too long can damage trees.

Proper Methods and Materials of Guying and Staking

Staking and guying a tree trunk to keep it upright can be a necessary, temporary support system, but does not compensate for poor root development and establishment long-term.

  • Guying is temporary and typically used on larger trees that are transplanted balled-and-burlapped. Three points of attachment provide the best support for these large-trees.
  • Staking connects the trunk to a nearby steel or wooden post. This is a common approach on smaller trees or containerized tree stock.
  • Underground stabilizing systems are also effective and economical for stabilizing the root balls on larger balled-and-burlapped trees. There are several commercial anchor systems available.

The cardinal sins of support include: staking trees too high, too tightly, and for too long which all cause tree damage. Improper staking can cause stem abrasions and trunk girdling. Review the anchor, attachment point, and tension on a regular basis, adjusting as needed to make certain the supports are effective and not damaging the tree. If a tree is supported, the ties and guys should be removed as soon as feasible, usually no later than after one growing season or one year. For more information see Purdue extension publication, Tree Support Systems.

Related Sources:
Stake or not to stake, that is the question?!, The Landscape Report
Tree Support Systems, The Education Store
Planting and Transplanting Landscape Trees and Shrubs, The Education Store
Latest Issue of the Purdue Landscape Report, Got Nature Post
Plant for the Sun!, Got Nature Post

Lindsey Purcell, Urban Forestry Specialist
Purdue Forestry and Natural Resources


Got Nature?

Archives