Purdue University - Extension - Forestry and Natural Resources
Got Nature? Blog
Woodlots are dynamic, vital ecosystems in the urban and suburban landscapes of the Midwest. People own these small wooded lots in urbanized areas for a variety of reasons: timber production, firewood production, recreation, wildlife habitat, aesthetics and alternative forest products. Many owners who keep and nurture these natural areas are motivated by powerful, non-economic motives based primarily on aesthetics and environmental protection.
This new Purdue Extension publication titled Indiana’s Urban Woodlots is a great way to aid you in a management plan and build your knowledge of what trees can do for you and the environment. This 24-page booklet covers benefits of trees, laws and zoning, stewardship planning, management, planting and renewal, and more.
View The Education Store for this and other Purdue Extension publications. Just type keywords in the search field to find the resources you need.
Lindsey Purcell, Urban Forestry Specialist
Department of Forestry and Natural Resources, Purdue University
Lenny Farlee, Sustaining Hardwood Extension Specialist
Hardwood Tree Improvement and Regeneration Center (HTIRC)
Department of Forestry and Natural Resources, Purdue University
An unsatisfactory approach to tree maintenance or pruning is “topping” it. Topping is the indiscriminant removal of branches of a tree above an arbitrary height, leaving unnatural, grotesque stubs and misshapen tree forms. In addition, increased risk tree conditions are introduced with development of decay, weak branch attachments and poor health.
Large evergreen trees do not respond well to topping. The removal of the upper main stem through topping opens the tree to internal decay, disease or damaging insects; it also removes the most productive portion of the tree. The practice of topping to control tree size or growth is not justified. If the tree is too large to fit the space, it should be removed and replaced with a smaller, more suitable species for its growing space.
Be aware that unprofessional tree service crews use this approach because it takes little skill and is easiest for them to perform. Do not let yourself be persuaded that topping serves your best interest; both you and your tree will suffer from such mistreatment.
The topmost part of an evergreen whose shape is pyramidal, such as a spruce tree, has a growing point known as the apical meristem. In evergreen trees, the apical meristem contains a hormone that suppresses lateral growth, helping it to keep its excurrent or pyramidal form. The further away from the tip (apical meristem), the less affect this hormone has on the lateral growth of the tree’s branches. This is why spruce trees have that pyramidal shape and are not more rounded or decurrent. By topping evergreen trees, it will destroy the apical dominance of the plant and result in growing more round than tall with a misshaped top. It will try to re-establish apical dominance as it matures, but it will most likely look very unusual and not like these species should appear with multiple competing growing tips. Remember, this is a natural form for many evergreens to help shed the heavy loads from snowfall. Remove the apical meristem (tip), and you reduce the suppression of lateral growth. This affects the shape of the spruce tree and exposes it to potentially splitting the tree down the trunk as well as exposure to the problems associated with topping.
Resources
Trees are Good
What’s Wrong with Topping Trees?
Lindsey Purcell, Urban Forestry Specialist
Department of Forestry and Natural Resources, Purdue University
Fire blight is infecting flowering pear trees in large numbers in Indiana for the third consecutive year with a Purdue Extension specialist again urging homeowners to check their trees for symptoms.
Symptoms of the potentially deadly disease with no cure are wilting shoots, cankers on branches and blackened leaves, which give the disease its name because trees appear to be scorched.
Resources
Purdue Pest and Plant Diagnostic Laboratory
The Education Store
Because agriculture dominates the midwestern landscape, it has a huge impact on environmental quality. Agricultural producers are often advised to adopt practices that help to reduce the impact of agriculture on the environment. However, like all humans, they are often reluctant to change, which makes the work of conservation professionals extremely challenging. In this publication, we explore the myths and realities around what motivates farmers to adopt conservation practices. We draw on the authors’ combined research and applied practitioner experience with farmer adoption of conservation practices. Most evidence is based on studies and observations of traditional row-crop farmers in the midwestern United States.
Adoption of Agricultural Conservation Practices
The Education Store
Purdue Extension
Extreme cold last winter, unrelenting winds and unusually large amounts of salt that were applied to roads, sidewalks and parking lots are taking their toll on landscape plants this spring, a group of Purdue University experts say.
They are seeing considerable damage and expect more this summer and beyond. While it is difficult to determine winter injury until bud break, they say it is now time for homeowners and others with ornamental plants to evaluate their plants for damage that needs to be corrected.
American elms have been the victim of a decimating disease known as DED or Dutch Elm Disease. However, there are a few that linger and remain, gracing our city streets with their majestic arching form. Many elms are mistakenly identified as American; however, there are many other “weedy” elms that have naturally inhabited our urban landscape. Due to the incredible interest in these trees, plant breeders have developed resistant American elms which are showing excellent results. Unfortunately, many of those trees proved to be susceptible to other diseases such as Elm Yellows.
Providing that the tree has been identified as an American elm, proper management is required to maintain its health and vigor to provide a sustainable tree in the landscape.
Strategies include:
Sanitation: Quick removal of diseased trees and symptomatic branches is necessary in managing this disease. Removal of the damaged parts reduces breeding sites for the elm bark beetle and removes the fungus from the vicinity. Branches with “flagging” symptoms should be removed, making a cut well behind (5-8 ft.) any visual symptoms.
Pesticide Applications:
Insecticides to kill bark beetle vectors – Attempt to control the insect vector population by applying an insecticide. Timing of the application may depend on the type of insecticide you have selected. Some insecticides may target the spring feeding sites while others target the overwintering sites and should be applied during late autumn. Use of this management option should be considered carefully. It is difficult to attempt control over this beetle population due to the timing factor, the complete coverage issue, expense and pesticide exposure.
Preventative fungicide injections – There are effective fungicides capable of protecting elm trees from infection, but this method of management should be considered carefully. Fungicide injection must be performed by someone trained in the technique and may be expensive. Protection lasts 1-3 years and then must be repeated. In addition, some researchers are concerned that repeated wounding of the tree (by drilling holes) for the injection may open trees to decay. If there is concern for infestation, it is critical to contact a reputable tree care company specializing in good plant healthcare. Always contact an International Society of Arboriculture Certified Arborist to help insure best practices. For more information on DED and management strategies, click on the links below.
Resources
Dutch Elm Disease
Diseases in Hardwood Tree Plantings
Pest Tracker: Dutch Elm Disease
Lindsey Purcell, Urban Forestry Specialist
Department of Forestry and Natural Resources, Purdue University
I am noticing several weeping cherries in the neighborhood which appear to be damaged, maybe dead over the winter. Forsythia bloom was poor, and my Cornus mas failed to bloom too. Will they recover?
Damage is just now starting to reveal itself due to the late growing season this year. Cherry trees appear to have been hit very hard, especially sweet cherries with over 90% of the crop damaged. Many landscape trees bloomed sporadically or not at all due to the extreme cold. Redbuds were light to no bloom but appear to be leafing out fine. Forsythia seems to be dependent on species and if they are planted in a protected area or microclimate. Many forsythia flowered well this spring, but many in open, exposed areas bloomed very little. Also it appears that Cornus mas is failing to bloom as well. Another consideration is impact of the drought from last year. I believe we will be seeing even greater impact with extreme cold providing an additional blow to our trees and shrubs. Plants may fail to bloom but still be alive.
The best suggestion is be patient and to provide good cultural practices with water when needed this spring and summer and provide the proper levels of mulch. Avoid fertilization and only lightly prune when necessary. Most likely trees are in stress conditions, still in recovery from the previous drought along with the extreme cold. Too much care can be lethal.
Resources
Pruning Ornamental Trees and Shrubs
Why Plants Fail to Bloom
Lindsey Purcell, Urban Forestry Specialist
Department of Forestry and Natural Resources, Purdue University
This winter was a brutal one for sure, but the emerald ash borer still has plenty of life left in it.
Although the Midwest experienced abnormally cold temperatures this winter, it is unlikely that populations of the highly destructive beetle were significantly affected by it, said Adam Witte, exotic forest pest educator in the Purdue University Department of Entomology.
“Headlines have been circulating, suggesting that EAB may have met its match,” Witte said. “But the EAB, as well as most insects in colder climates, is effective at surviving cold temperatures.”
EAB larvae overwintering within ash trees die when temperatures reach minus-28 degrees Fahrenheit below the bark, Witte said. U.S. Forest Service scientists predicting areas in North America where temperatures were cold enough to kill EAB larvae conclude that only parts of Minnesota and North Dakota historically have reached temperatures that low.
Contacts
Adam Witte, Exotic Forest Pest Educator
Department of Entomology
Matthew Ginzel, Associate Professor
Departments of Entomology & Forestry and Natural Resources
Early spring brings the emergence of new life in the forest. Unfortunately, not all that life actually belongs there. Several invasive plants are encroaching on woodlands and crowding out the desirable native plants we enjoy and wildlife depend upon for food and shelter. One of the characteristics of some invasive plants is early leaf emergence and growth, which allows us to scout for their presence more easily, while native species are still waking up from winter. Two species that start growing very early in the spring are garlic mustard and Asian bush honeysuckles. Both plants are rapidly greening up and growing as I speak. Look for the kidney to heart shaped leaves of garlic mustard on the forest floor. This biennial will soon be sending up flower stalks from the second season plants that will have white four-petaled flowers. The flower stalks can be up to three feet tall or more depending on the health of the plant and the quality of the growing site.
Early spring leaves of garlic mustard.
Asian bush honeysuckle is a medium to large bush that also inhabits the forest understory and edge or disturbed areas. Leaves and twigs area arranged opposite each other. If you slice the stems open, they are hollow inside with fuzzy brown or tan lining. Flowers are yellow, white or even pinkish and tube-shaped. The fine twigs and stems have a light tan or gray-tan color. Leaves are rapidly expanding now, so they will be easily detected until our native plants catch up with leaf cover.
Early growth of Asian bush honeysuckle.
Controlling these plants helps native plants continue to thrive and provide habitat for our wildlife. Garlic mustard can be pulled from moist soil. If seed pods are present, remove the plants from the area and burn or bury them. Foliar herbicides like glyphosate products may be used to spray garlic mustard. If the plants have already set seed pods, the seed may become viable even if the plant has been sprayed, so removal may be the only effective treatment at that time.
Asian bush honeysuckle can be controlled in several ways, depending on the size of the plants. Small plants can be pulled from moist soil. Foliar sprays with herbicides like glyphosate can be effective. Large bushes may be cut and the stumps treated with a brush-killing herbicide. For any herbicide application, read and follow label directions.
Purdue University has invasive species information resources at FNR Extension and Indiana’s ‘Most Unwanted’ Invasive Plant Pests/Indiana Cooperative Agricultural Pest Survey (CAPS) Program.
Lenny Farlee, Sustaining Hardwood Extension Specialist
Hardwood Tree Improvement and Regeneration Center (HTIRC)
Forestry and Natural Resources, Purdue University
American chestnut fruit protected by a spiny bur. Photo: Dr. Shaneka Lawson, USDA Forest Service, Purdue HTIRC
In the late 1800s, 25% of hardwood trees in North America’s eastern forest were American chestnuts, 40 meters high and two meters across, they provided abundant resources for both people and wildlife in the form of food, shelter and building materials. Lightweight, rot-resistant, straight-grained and easy to work with, chestnut wood was used to build houses, barns, telegraph poles, railroad ties, furniture and even musical instruments. The rapid decline of the chestnut due to the pathogenic fungus Cryphonectria parasitica has been a subject of much debate and despair over the years, but now, chestnuts engineered to battle the fungus might give the iconic trees a chance to reclaim the North American stage.
Research conduced in 2014 was taking genes from wheat, Asian chestnuts, grapes, peppers and other plants and inserting them into American chestnut trees. William Powell of S.U.N.Y.–ESF and scores of collaborators, created hundreds of transgenic trees with the goal of almost 100 percent genetically identical wild American chestnut yet immune to C. parasitica. Testing and gathering data continues to help with future research.
Douglass Jacobs, the Fred M. van Eck Professor of Forest Biology at Purdue University, and a team of scientists at Purdue, use genomics which involves working with the complete set of an organism’s genetic material, to learn more about what causes disease. Genomics also can help identify the genes responsible for useful traits such as pest resistance.
Blight began afflicting the American chestnut in the 1900s, killing billions of trees. Despite being the target of decades-long tree-breeding efforts, the chestnut’s prospects remain in doubt. The list of at-risk species also includes ash, butternut, and bristlecone pine among other members of the five-needle white pine family.
The Hardwood Tree Improvement & Regeneration Center, a joint effort between Purdue and the Forest Service, for years has maintained a breeding program for pest resistance. Almost all of the center’s efforts to date have focused on traditional tree breeding and genomics.
“The chance to work with chestnut and help reintroduce it back to the landscape was a big reason I took the Purdue job in the first place back in December of 2001,” Jacobs said. “Watching species disappear from the landscape provides me personally with a lot of motivation to contribute whatever I can toward helping to save some of these at-risk species.”
To learn more about his research and collaboration with the U.S. Forest Service view full article Biotechnology offers holistic approach to restoration of at-risk forest tree species – Purdue University News, by Purdue Agriculture News.
Resources
A New Generation of American chestnut Trees May Redefine America’s Forests – Scientific American
Consequences of Shifts in Abundance and Distribution of American Chestnut for Restoration of a Foundation Forest Tree – Forests Open Access Forestry Journal
Transgenic American chestnuts show enhanced blight resistance and transmit the trait to T1 progeny – Science Direct (Plant Science)
Scientists Work to Create a Blight-Resistant Chestnut with Hopes of Restoring Tree to America, Forest Service, U.S. Department of Agriculture
FNR Hardwood – American Chestnut, Purdue Arboretum Explorer
Hardwood Tree Improvement Regeneration Center (HTIRC) Research Publications
American Chestnut Trees return to the Hoosier National Forest, Indiana Woodland Steward
Forest Regeneration and Restoration Laboratory, Purdue Forestry and Natural Resources, Dr. Doug Jacobs
Indiana American Chestnut Foundation
Purdue Extension – Forestry and Natural Resources (FNR)
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