Got Nature? Blog

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


Posted on October 26th, 2018 in Forestry, Plants | No Comments »
Figure 1

Figure 1. Bark cracking due to Southwest injury.

The time is now to start protecting your trees!  Now that your ears are perked up, let’s talk a bit about Southwest injury on trees.

Bark cracking (Fig.1) is a phenomenon that occurs in many species of trees and can have many causes. One of the most common types of bark cracking is termed Southwest injury. Southwest injury occurs during the winter months on the lower section of the trunk on the southwest side. This happens when there is a sudden temperature drop, for example, the sun going behind a cloud during the winter. The freeze-thaw cycle happens very quickly when there is a change from very warm to cold conditions, which results in a crack. If there is a snow pack, the reflection of sunlight on the bark will actually increase the temperature in the bark.

Figure 2

Figure 2. Snow can increase the reflection of sunlight to the tree, thus increasing the likelihood of Southwest injury.

Usually Southwest injury occurs on thin-barked trees, such as Acer spp., Cercis spp., Malus spp., and many others (Fig. 3). A thin-barked tree lacks the amount of cork cells in thicker-barked trees, thus allowing the vascular tissue to be located very close to the bark.  Thick bark trees tend to be more resistant to cracking due to a greater lag in the freeze/thaw cycle. Trees that are under stress due to environmental factors, herbicide injury, and/or insect and disease are more susceptible to cracking.

No matter the initial cause of the crack, the common denominator of a crack in the bark is a pre-set wound. The freeze-thaw cycle during the cold months causes the point of injury to expand and contract. Like with your vehicle windshield, a small point of injury in bark will expand and contract due to sudden heating or cooling, thus causing a large crack.

Figure 3

Figure 3. Bark cracking on thin-barked species, such as maple, is common due to Southwest injury.

Any type of cracking that occurs, originates from a point of injury, such as a pruning or other mechanical injury. These are horizontal cracks that can range from <1” to the entire length of the trunk, though are usually localized near the bottom of the trunk (Fig. 4).

Once trees are greater than about four inch caliper, the likelihood of Southwest injury is diminished.  On trees four inches or less, tree guards (also called tree wraps) should be installed over each trunk.

White tree guards may help prevent this from occurring due to the reflection of the sun, preventing overheating on the bottom of the trunk (Fig. 5) In order to prevent cracking, try to prevent any type of mechanical damage that could cause cracking in the winter. Bark cracks become visible most often during the late winter/early spring. Tree guards should be removed in the spring, because the guards become a problem with disease due to moisture within the guard.

Figure 4

Figure 4. Southwest injury typically causes cracking up the trunk from close to the root flare

In some circumstances a healthy plant may heal, partitioning off the damaged area, but the bark on a plant under stress, due to drought, herbicide damage, etc., may last the entire life of the tree.

For full article, check out the Landscape Report

Figure 5

Figure 5. White tree guards can help minimize Southwest injury by reflecting sunlight. Joseph OBrien, USDA Forest Service, Bugwood.org.

Resources
Trees and Storms, The Education Store
Pruning Ornamental Trees and Shrubs, The Education Store
Why Hire an Arborist, The Education Store
Why Is My Tree Dying? The Education Store
Weeping Cherry Trees Appear to be Damaged or Dead. Was This Past Winter Hard on These Types of Trees?, Got Nature? Blog

Lindsey Purcell, Urban Forestry Specialist
Purdue Forestry and Natural Resources


Posted on October 18th, 2018 in Disease, Forestry, Plants | No Comments »

The DNR Division of Entomology & Plant Pathology has discovered that a shipment of boxwood plants infected with boxwood blight was shipped to Indiana in May.

Boxwood Blight

The black streaks on these stems are typical of boxwood blight. Photo by M. Daughtrey, New York.

This is important because boxwood blight (Calonectria pseudonaviculata) is a fungal disease that infests members of the popular Buxaceae family, and is often transported through the nursery trade. Hosts include Buxus (boxwood), Pachysandra (Japanese spurge) and Sarcococca (sweetbox).

In total, 23 stores in Indiana received infected material in early spring (particularly “Graham Blandy” cultivar), and it’s possible that members of the public inadvertently purchased some plants.

The fungus, which can lay dormant in drier conditions, can be found on all above-ground portions of the plant and presents itself as dark leaf spots. It causes rapid defoliation, which typically starts on the bottom of the plant and moves toward the top. This fungal pathogen can move through sporulation  in water and from dropped leaves. As a result, infection can spread to surrounding plants from a single infected plant.

If you suspect one of your plants shows signs and symptoms of boxwood blight, please call (866) NO EXOTIC (866-663-9684) use the information at dnr.IN.gov/entomolo.

For more information on this pathogen see the following link extension.purdue.edu/extmedia/BP/BP-203-W.pdf

A DNR inspector found the plants at a national chain home and garden store in early October. The shipment originated at a nursery in Oregon. It was also sent to stores in 11 other states.

Upon confirmation of boxwood blight on these plants by the Purdue Plant and Pest Diagnostic Lab, the DNR required that the chain remove all boxwood from their shelves for disposal and that the stores mitigate the area through disinfection to ensure that the pathogen is no longer present and able to infect further shipments of plants.

The DNR is currently surveying for boxwood blight in Indiana. To date, the DNR has not found the pathogen, except for a few interceptions like this one.

To view all DNR news releases, please see dnr.IN.gov.

Resources:
Boxwood Blight Found in Indiana, full Landscape Report
Boxwood Blight, The Education Store, Purdue Resources

Tom Creswell, Clinical Engagement Associate Professor
Purdue Botany and Plant Pathology

Lindsey Purcell, Urban Forestry Specialist
Purdue Forestry and Natural Resources


Posted on September 3rd, 2018 in Forestry, Plants, Woodlands | No Comments »
Home Tree

Review trees on a regular basis for health and safety.

Trees provide many benefits for our homes with shade, beauty and improved air quality as just a few, however, if a tree has defects which could lead to a failure, your shade tree could become a liability. It is important to understand that tree owners have a legal duty to inspect and maintain their trees. All property owners should take reasonable steps to protect themselves and others by taking a look at trees around the property on a regular basis.  Here are some suggestions to consider in making your trees safer for everyone.

Reduce Tree Liabilities: In general, the law obligates tree owners to periodically inspect their property and take reasonable care to maintain it and this includes trees. Routine inspections also exhibit that the tree owner is actively managing their property and trees and thereby reduces their liability if a failure does occur.

When it comes to trees, it’s best to have a professional conduct risk and tree health assessments if there is any uncertainty.  However, Homeowners can look for tree defects, including dead branches, broken limbs, decay pockets or other conditions that reduce a tree’s strength. Review the tree from the top, down. Look at the tree’s crown, main branches, trunk and root area to see if there is anything abnormal. If you find easily recognizable defects like dead and falling branches, cavities, fungal fruiting bodies or newly-formed leans on a tree, consider having the tree examined by a certified arborist. This is especially important after a severe storm. Trees can easily survive normal weather conditions for many years, however, excessive winds can have a real impact.  Make certain trees aren’t removed prematurely out of fear without making an informed decision along with the arborist.

Tree Inspections

Understanding tree health and risk is challenging for tree owners. It is best to find a ISA Certified Arborist to help with identifying tree issues.

Tree leans

Recent leans developing on trees may be corrected, however, they do pose a risk and should be inspected by an arborist.

Tree fungus

Look for unusual fungal growths on you trees. This indicates decay which can lead to a higher risk of failure.

 

 

Schedule Tree Work: If risk or health issues are found during the inspection, schedule the tree work with a qualified arborist. Be sure to find a tree care company in the area that is reputable and can provide references. Also, being fully insured is another important item to be aware when choosing an arborist.  To find an arborist in your area, go to the website, www.treesaregood.org.

Inspection on a regular basis: Trees should be inspected regularly. These inspections should occur during the growing season and dormancy. Further inspections should be conducted after major weather occurrences. At a minimum, trees should be inspected every five years by an arborist, especially if there is decline and dieback present in your trees.

Article shared by: The Landscape Report, Why Tree Inspections?.

Resources:
Trees and Storms, The Education Store, Purdue Extension’s resource center
Tree Risk Management, The Education Store

Lindsey Purcell, Urban Forestry Specialist
Purdue 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


Posted on July 20th, 2018 in Forestry, Plants | No Comments »

Tree lineThe latest issue (18-11) of The Purdue Landscape Report has been released July 17th.  This issue contains four articles about common tree care accidents, problems of tree transplant shock, leaf loss, and poison ivy.

Will my Trees Recover After Losing their Leaves?
Damage caused by defoliating insects can be quite shocking. An effective response to this sort of defoliation should be based on your understanding of how losing leaves affects plant health.

Poison Ivy
Most landscape professionals and gardeners have heard of the wise advice “leaves of three, let it be” referring to the pest plant poison ivy. While not quite as catchy, the saying really should be “leaflets of three, let it be.”

Homeowner Tree Care Accidents
The Tree Care Industry Association (TCIA) conducted an analysis of 62 civilian tree care-related accidents reported by the media from January 2017 to June 2018. TCIA is a trade association that promotes professional tree care and discourages homeowners from taking unnecessary risks caring for their trees themselves.

Common Abiotic Problems of Ornamentals: Transplant Shock
Transplant shock occurs when plants become stressed due to poor root establishment, often mimicking drought stress.  The severity of transplant shock is dependent on many factors, which include plant species, soil type/quality, moisture, temperature, growth stage of the plant, root loss from the nursery, as well as many other factors.

Please check out the full articles at The Purdue Landscape Report 

Resources:
Poison Ivy, The Education Store, Purdue Extension resource center
Planting & Transplanting Landscape Trees and Shrubs, The Education Store
Tree Support System, The Education Store
Construction & Trees: Guidelines for Protection, The Education Store

Cliff Sadof, Entomology Extension Coordinator
Purdue Department of Entomology

Rosie Lerner, Extension Consumer Horticulturist
Purdue Department of Horticulture and Landscape Architecture

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

Kyle Daniel, Nursery & Landscape Outreach Specialist
Purdue Department of Horticulture and Landscape Architecture


Posted on July 1st, 2018 in Plants, Safety | No Comments »

Most terrestrial plants are sessile. This inability to move forces has brought alternative methods to defend themselves. Typically, plants use three basic mechanisms of defense: avoidance, escape or tolerance. A recent work notes that plants may have evolved a fourth method; where healthy tissue is sacrificed in an effort to confine harmful bacteria to a small portion of the leaf.

SOBER1 in plantsBrown spots, if observed on previously unmarred leaves, may result from the plant employing this technique to slow or prevent bacterial spread. Scientists at the Salk Institute have identified a plant enzyme denoted SOBER1 that plants use to seemingly lower their resistance to infection. Future study on the gene may lead to ways to boost natural immunity or contain infections that would otherwise decimate entire agricultural crops and biofuel resources.

Additional experiments involved several model plant species (Arabidopsis, oilseed rape, and tobacco) and evaluated the structure and function of SOBER1 and an immune protein known as AvrBst. The ultimate goal of this work is to understand how bacterial resistance works in plants. The information gained may help identify new methods of improving agricultural and biofuel crop resistance to harmful bacterial infections.

References
A hydrophobic anchor mechanism defines a deacetylase family that suppresses host response against YopJ effectors, Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-02347-w, Marco Bürger, Björn C. Willige, Joanne Chory.
Unusual plant immune response to bacterial infection characterized, ScienceDaily, 8 January 2018, Salk Institute.

Resources
Consumer Horticulture: Fertilizing Woody Plants, The Education Store, Purdue Extension
Shrubs and Woody Vines of Indiana and the Midwest: Identification, Wildlife Values, and Landscaping Use, The Education Store, Purdue Extension

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


If you’ve ever had to work on a tree leaf collection, no doubt you included a leaf from Indiana’s state tree. Also known as tulip poplar and yellow poplar, the tuliptree is actually not a poplar at all. It is a member of the magnolia family known botanically as Liriodendron tulipifera.

Indiana Tuliptree

A tuliptree, the state tree of Indiana.

The tuliptree is native to most of the eastern half of the United States and prefers rich, moist, well-drained, loamy soil. It is found throughout Indiana, but it is more prevalent in the southern two-thirds
of the state.

Its unusual flowers inspired the common name. The flowers are shaped much like a tulip with greenish-yellow petals blushed with orange on the inside. Because they generally are found high in the leaf canopy, the flowers often go unnoticed until they drop off after pollination. The leaves of this tree are also quite distinct — each one has a large, V-shaped notch at the tip.

Because tuliptrees transplant easily and grow fast, they are a popular choice for in home yards. But don’t be fooled by its small size in the nursery. Give a tuliptree plenty of room in your landscape plan. A tuliptree can reach as tall as 190 feet where it’s allowed to thrive, but it is more likely to reach 70 feet tall as a mature landscape specimen. Tuliptree is not without its share of pests and diseases. Among the most common are leaf spots, cankers, scale insects, and aphids….

For full article view “State tree a popular landscape choice,” Morning AgClips.

Related Resources:
Pruning Ornamental Trees and Shrubs, The Education Store-Purdue Extension resource center
Tulip Poplar: Is Indiana’s State Tree a Protector for the Rare American Ginseng Plant?, GotNature?, Purdue Extension – Forestry and Natural Resources

Rosie Lerner, Extension Consumer Horticulturist
Purdue University, Horticulture & Landscape Architecture


Trees offer many functional and aesthetic benefits, but one of the most common is shade. Because of this, one of the most important aspects of tree selection and planting is placement. Improper placement of trees can diminish the value of the tree on the site. The tree can actually become a liability if it conflicts with infrastructure or just does not providing any useful function at all. It’s important to consider and energy efficient design to obtain shade where it’s needed most such as south or west facing structures.Tree Shade

In this hemisphere, the sun is in the south and the source of cold weather is in the north. Whenever possible, place openings for sunlight and radiant heat primarily on the southern exposure, then on the west and east. For energy efficiency in winter, use the low arc of the sun to capture the maximum amount of warmth through east-, west-, and south-facing windows. Windows with a northern exposure are a source of cool air from prevailing winds during the hot months. So, give the north minimum exposure and maximum natural protection in the winter.

When selecting trees for energy efficiency, don’t plant evergreen trees near the house on southern exposures. Trees may provide some shade and screening but will also block out the warming effects of the sun during winter months. When choosing trees for shade and solar gain, choose larger, deciduous-canopy trees, which provide an advantage year-round. This means shade in the summer, blocking the sun’s energy. In the winter, after leaves have dropped, the sun’s energy can pass through the tree and into the window.

Tree Shade

Figure 1. Protection from the summer sun.

Select good quality trees from a reputable source that are suitable for your location. The old adage, “you get what you pay for” goes for nursery stock as well.  Correct placement is critical for an energy-efficient design and reduced maintenance as the tree grows and matures. Be certain the mature height and spread fit the location before purchase and planting the tree. This allows the tree freedom to spread into the design space naturally without excessive pruning needed to prevent conflicts with the home. However, the tree still must be close enough to the house for the canopy to provide shade. A good rule of thumb to begin placing the tree at least 20 feet from the house. For larger shade trees, you may need to plant as far as 40 feet from the house to insure room for growth (Figure 1).

Trees provide many benefits besides shade whichincludes cleaner air and increased property values. These ecosystem services are the reason why we plant trees, besides beautifying our landscape.

The functional benefits of shading help make homes energy-efficient by creating a cooling effect during the hot summer months and by allowing passive solar gain during cold winter months. However, proper selection and placement is critical to make the tree work for your site.  Choose wisely, plant properly.

Full article from Purdue Landscape Report.

Resources:
Tree Selection for the “Un-natural” Environment, The Education Store – Purdue Extension 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

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


Mile-a-minute vine covering trees

(Figure 1) Mile-a-minute vine grows more than 25 feet in height in one growing season, overtopping shrubs, small trees and growing up forest edges.  Image by: USDA APHIS PPQ Archive, USDA APHIS PPQ, Bugwood.org

Preventing the establishment of new invasive species is priority number one and the best expenditure of limited resources in an invasive species management program. Next in priority is early detection of and rapid response (EDRR) to the first report of a new invasion. Stopping invasive species from entering or, next best, at their initial point of introduction saves the incalculable costs later-on associated with rapidly spreading, all-consuming invasive species populations. The verification of a report of mile-a-minute vine (Persicaria perfoliata) on a property in Monroe County, Indiana on May 14, 2018 sets a historical prescedence demonstrating a growing capability of detecting and reporting new invaders. The population was very small at this spot and had apparently been sprayed by a homeowner with herbicide, not necessarily to kill the mile-a-minute, but likely to kill the companion multiflora rose.

Our hope is that this is the only instance of mile-a-minute vine in Indiana. There is a significant probability that it is not! In the coming months, a more thorough survey of this property and surrounding area will be conducted to look for more of the vine. But now Indiana stands on high alert as natural resource professionals keep a look out for more of this highly-invasive pest. However, there are too few professionals with eyes on the landscape. The more eyes trained to identify the very distinct characteristics of mile-a-minute, the higher the chance of us catching it before it explodes across the landscape, wreaking havoc and mayhem in our forests and fields, wildlife habitat and mushroom hunting and birding grounds.

Mile-a-minute leaves

(Figure 2) The leaves are simple, alternate, light green and a nearly perfect triangle shape.  Image by: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

All landowners, land stewards, and nature lovers are needed to be additional eyes looking for this insidious threat this summer and in coming years. Please take a moment to learn its identifying characteristics. If you think you have found it, please report it on EDDMapS (Early Detection & Distribution Mapping System) or from your smart phone on the GLEDN (Great Lakes Early Detection Network) app. If you are unsure if you are correctly identifying it, please contact a forester or other natural resource professional for confirmation or just report it in EDDMapS or the GLEDN app, along with photos, and a professional in your area will verify its identification before it actually gets posted.

Mile-a-minute identification:

Mile-a-minute vine is a member of the buckwheat family, Polygonaceae. Although its common name exaggerates its growth potential, this annual vine can grow as much as 6 inches a day and can reach heights of more than 25 feet within the growing season. It forms very dense, tangled mats, growing over shrubs, small trees and up the sides of forest edges (Fig. 1). The leaves are simple, alternate, light green and a nearly perfect triangle shape (Fig. 2). The delicately narrow, green to red-tinted stems, and the petiole (leaf stem) and midrib on the underside of the leaves are armed with small, stiff, recurved barbs (Fig. 3). Small, cup- or saucer-shaped leaf structures, called ocreae, encircle the stem at each node (Fig. 4). Clusters of small white, rather inconspicuous, flowers emerge from the ocreae. Flowers develop into clusters of deep, iridescent blue berry-like fruits, approximately 5 mm in diameter, each fruit containing a single black or reddish-black hard seed, called an achene. Seeds are dispersed by birds and mammals, including chipmunks, squirrels and deer, which eat the fruit. Floodwaters facilitate long distance dispersal of seed.

Mile-a-minute fruit berries

(Figure 4) Small, cup- or saucer-shaped leaf structures, called ocreae, encircle the stem at each node. Flowers emerge from the ocreae and develop into clusters of deep, iridescent blueberry like fruits.  Image by: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Mile-a-minute thorns

(Figure 3) The delicately narrow, green to red-tinted stems, and the petiole (leaf stem) and midrib on the underside of the leaves are armed with small, stiff, recurved barbs.  Image by: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Resources:
Mile-a-MinuteVine, FNR-481-W, The Education Store, Purdue Extension’s resource center
Mile-a-minute vine: What you need to know about the plant that can grow 6 inches a day, Indianapolis Star
Invasive Species – Indiana Department of Natural Resources (IDNR)
Ask an Expert – Purdue Extension-Forestry and Natural Resources
Indiana Invasive Species Council – Includes: IDNR, Purdue Department of Entomology and Professional Partners
Great Lakes Early Detection Network App (GLEDN) – The Center for Invasive Species & Ecosystem Health

Ron Rathfon, Regional Extension Forester SIPAC
Purdue Department of Forestry and Natural Resources


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