Got Nature? Blog

Purdue Landscape Report: Sawflies are frequent pests in the landscape that attack a wide variety of plants, from ornamental flowers to large trees. You might start to see them damaging plants around this time of year as the first generations hatch and begin to feed on foliage. They are often mistaken for caterpillars, which are the larval stages of butterflies and moths (Order Lepidoptera). However, sawflies are actually wasp-like insects (Order Hymenoptera).

Let’s review how to tell them apart. Products that are labeled for caterpillars do not always work on sawflies, so proper identification is important.

• The most reliable characteristic are the prolegs. Sawflies have 6+ pairs of prolegs, or false legs, while caterpillars have < 6 pairs of prolegs. (Fig. 1)
• When disturbed, sawflies will lift their posterior into an “S” shape. Caterpillars don’t display this behavior. (Fig. 2)

Integrated management recommendations

Early in the year, before hatching starts, look for sawfly oviposition on your plants. This will vary depending on the species of sawfly. For example, the European Pine sawfly eggs look like yellow-orange spots evenly spaced on the needles (Fig. 3). The Bristly Roseslug sawfly uses her ovipositor to cut a slit into the leaf petiole where she inserts eggs. The gooseberry sawfly lays eggs on a leaf vein (Fig. 4).

If the eggs are readily visible, manual removal will help reduce the populations. This is best accomplished in early spring before the eggs hatch. Use a tool to smash the eggs, or prune of the affected plant material.

You may not notice any problem on the plant until you start to see holes appearing in the foliage. Monitor regularly in the spring for holes and “window pane” damage (Fig. 5). This is the time of year when sawflies are hatching, so don’t wait any longer to check your plants. Sawfly management is best accomplished when the larvae are still small. Prune or shake off the larvae from the plant, or spray with a biorational material so as not to disturb natural enemies and cause a secondary pest outbreak later in the summer.

For more information on sawfly biology, check out this five-minute video: Slaying Sawflies with Purdue Plant Doctor.

Specific management recommendations can be found on the Purdue Plant Doctor website. Type “sawfly” into the search and click on the species you would like to read more about!

Read the original article on Purdue Landscape Report: Sawflies: the caterpillar pests that are not caterpillars.

The Purdue Hardwood Tree Improvement and Regeneration Center has signed a commercial partnership agreement with Tree Pro to distribute select hardwood seedlings from its breeding program beginning in March 2025.

The partnership, which will mark the HTIRC’s first commercial release of seedlings in its 25-year history, will see West Lafayette, Ind., based Tree Pro distribute bare root seedlings of six species across its timber select, conservation and wildlife lines. Timber select varieties will include black walnut, black cherry, northern red oak, white oak and pure and hybrid butternut. Conservation species include pure butternut and American chestnut. The wildlife line will feature select precocious white oak.

The HTIRC collection is available for purchase now on the Tree Pro website. Delivery of the seedlings is set for March 2025.

For over five decades, Purdue University and the HTIRC have assembled, tested and selected populations of Indiana’s most valuable hardwood tree species (black cherry, black walnut, northern red oak and white oak) for deployment across the Midwest’s Central Hardwood Forest region. Populations of all four species have been selected for stem straightness and growth rate and are under continuous improvement as breeders remove underperforming clones and seedlings from seed production areas.

Today, as a product of the HTIRC’s efforts, numerous progeny tests, grafted clone banks and orchards exist at Purdue properties across Indiana and are now producing commercial quantities of seed for distribution.  A commercial partnership with Tree Pro now gives the HTIRC an outlet to distribute its hardwood trees to landowners throughout the Central Hardwood Forest Region.

“Tree Pro’s established reputation with conservation groups, private landowners and foresters makes them an ideal distributor of the HTIRC’s select material,” said Matt Ginzel, director of the HTIRC. “We want to make it clear that this partnership will not take away from our existing relationship to provide seeds and seedlings to the Indiana Department of Natural Resources. This simply gives us another avenue to get our material into the hands of the public and to achieve our goal of increasing the value and resilience of woodlands by enriching the diversity of seedlings available for reforestation efforts.”

Tree Pro has been in business for 37 years and is known for its tree protection products (Miracle Tube) and lines of fruit and nut trees oriented to hunters and wildlife enthusiasts.

“When we were approached about the opportunity to distribute genetically diverse select hardwood seedlings from the HTIRC, we were instantly excited,” said Tommy Mills, co-owner of Tree Pro. “It brings our start as a company with black walnuts full circle.”

In addition to making selections on four major hardwood species, the HTIRC has been working to preserve and develop disease-resistant populations of two endangered native fine hardwood species –  butternut and American chestnut.

After more than 20 years of work, the HTIRC now possesses the most diverse collection of butternut in the United States, and has made significant advances in breeding butternuts resistant to the deadly butternut canker fungus. The HTIRC’s canker-resistant butternut program utilizes both pure butternut and hybrids between the butternut (Juglans cinerea) and the Japanese walnut (Juglans ailantifolia), with a program goal of decreasing the proportion of Japanese walnut genetics in the population while increasing overall canker resistance. A collection of pure, disease susceptible butternuts also is maintained for research purposes, and provides valuable seed for organizations and individuals that prefer pure butternut over hybrid butternut.

The American chestnut, once the backbone of timber production for all uses in the eastern United States and a prolific producer of nuts for animals and humans alike, is now functionally extinct due to the accidental introduction of the chestnut blight fungus in 1904. In collaboration with the American Chestnut Foundation and other entities, the HTIRC has assembled an American chestnut collection that represents pure American chestnuts from Indiana and neighboring states. It stands as one of the few grafted American chestnut collections in the country. While currently unavailable for public release, the HTIRC’s ongoing efforts to breed a blight-resistant American chestnut encompasses the use of both interspecific hybrid breeding and biotechnology to restore a long-lost forest species.

“The mother trees for HTIRC’s Timber Select lines were all selected for straight stems with few defects like low forks that can negatively impact standing timber value, while the Timber Select butternuts were selected for their resistance to butternut canker disease,” said Caleb Kell, operational tree breeder for the HTIRC. “Landowners have a good chance of getting similar characteristics out of their seedlings if they are planted on suitable soils with deer protection, which is one of Tree Pro’s specialties.”

Here is a quick list of what is available for purchase:

• HTIRC Timber Select Black Walnut
• HTIRC Timber Select Black Cherry
• HTIRC Timber Select Northern Red Oak
• HTIRC Timber Select White Oak
• HTIRC Timber Select Pure and Hybrid Butternut
• HTIRC Conservation Pure Butternut
• HTIRC Conservation American Chestnut
• HTIRC Wildlife Select Precocious White Oak

View full article with descriptions of seedlings available along with additional photos, Purdue Forestry and Natural Resources News & Stories: HTIRC Partners with Tree Pro to Distribute Hardwood Seedlings.

Other resources:
Forestry & Natural Resources
Tropical HTIRC
An Introduction to Trees of Indiana, The Education Store, Purdue Extension resource center
Native Trees of the Midwest, Purdue University Press
Shrubs and Woody Vines of Indiana and the Midwest, Purdue University Press
ID That Tree, Playlist, Subscribe to Purdue Extension – Forestry and Natural Resources YouTube Channel
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store
Finding help from a professional forester, Indiana Forestry & Woodland Owners Association
District Forester, Indiana DNR Division of Forestry, for over 10 acres of woodlands
Directory of Professional Foresters, Indiana Forestry & Woodland Owners Association (IFWOA)

Wendy Mayer, FNR Communications Coordinator
Purdue University Department of Forestry and Natural Resources

Welcome to ID That Tree! In this edition, Purdue Extension Forester Lenny Farlee highlights a native bramble species—black raspberry. A member of the Rubus family, black raspberry is commonly found throughout Indiana, making it useful to recognize its key features. Tune in to learn how to identify this plant by its unique leaf pattern (and how it’s different from autumn olive), understand its role in wildlife habitats and explore its many uses and benefits!

If you have any questions regarding wildlife, trees, forest management, wood products, natural resource planning or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources:
ID That Tree – Video Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Purdue Arboretum Explorer
Conservation Tree Planting: Steps to Success, Purdue Extension – FNR YouTube Channel
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Report Invasive, Purdue Extension
Fifty Common Trees of Indiana, Purdue Extension – FNR
Habitat University, Episode 12 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
Native Trees of the Midwest, The Education Store
Professional Forester, Indiana Forestry Woodland Owners Association
Forest Improvement Handbook, The Education Store
Find an Arborist, International Society of Arboriculture

Lenny Farlee, Extension Forester
Hardwood Tree Improvement and Regeneration Center
Purdue Department of Forestry & Natural Resources

Hoosier Ag Today: White-tailed deer are very important to Indiana woodlands. But in many areas of the state, deer populations have grown far beyond what the land can support.

Trail cameras monitor deer impact on woodlands. Integrated Deer Management Project, Purdue University photo.

“Through their browsing and what they eat, they can actually reduce plant diversity and limit the growth of some of our tree seedlings, such as Oak, which are both economically and ecologically important,” says Jarred Brooke, Purdue Extension Wildlife Specialist.

“They can actually cause issues with increases in the invasive species that they don’t eat, like Japanese stilt grass or garlic mustard,” he says.

For woodland owners across Indiana who might not be sure if deer are even a problem on their property, how can they better understand and measure deer impacts?

“I think the first step is being aware and being tuned in to the problems that deer can cause,” he says. “Fortunately, with the help of The Nature Conservancy here in Indiana, we at Purdue Extension created a series of publications and videos called the Deer Impact Toolbox, which are designed to help landowners really understand, monitor, and address the impacts that deer have in their woodlands. These resources are a great starting point for any landowner that is interested in learning more about deer impacts.”

He adds that the best way to manage those impacts from deer are hunting, habitat management, and plant protection.

“Through the reduction of the number of deer by harvesting does on your property, that can be an effective way to reduce their impact,” he says. “Also if you can improve the habitat for deer on your property, either through forest improvement or through a timber harvest, you can actually create more food on the landscape, which reduces overall dear impact.

“The last big way is through protecting the plants that you’re trying to keep deer from browsing. That can be fencing, tree plantations, putting tree tubes or tree shelters on young trees, or fencing sensitive areas from deer browsing,” he says.

Read the Deer Toolbox Publications: Deer Impact Toolbox.

View the original article and listen to the Hoosier Ag Today’s radio News in the Hoosier Ag Today April 2025: Managing the Impact of White-tailed Deer on Indiana Woodlands.

Resources:
Purdue Extension Pond and Wildlife Management
Ask an Expert: Wildlife Food Plots, video, Purdue Extension – FNR YouTube Channel
How to Build a Plastic Mesh Deer Exclusion Fence, The Education Store
A Woodland Management Moment – Deer Fencing, Purdue Extension – FNR YouTube Video
Managing Your Woods for White-Tailed Deer, The Education Store
Bovine Tuberculosis in Wild White-tailed Deer, The Education Store
Handling Harvested Game: Episode 1, Field Dressing, video, Purdue Extension – FNR YouTube Channel
Deer Harvest Data Collection, Got Nature? Blog, Purdue Extension – FNR
How to Score Your White-tailed Deer, video, Purdue Extension
White-Tailed Deer Post Harvest Collection, video, Purdue Forestry and Natural Resources
Age Determination in White-tailed Deer, video, Purdue Extension
Handling Harvested Deer Ask an Expert? video, Purdue Extension – FNR YouTube Channel
Subscribe to Purdue Extension-Forestry & Natural Resources YouTube Channel, Wildlife Playlist

Jarred Brooke, Wildlife Extension Specialist
Purdue Department of Forestry and Natural Resources

Hoosier Ag Today

The Hardwood Tree Improvement & Regeneration Center (HTIRC) continues to share top forest research as scientists, experts and partners further the mission of tree improvement, management, and protection of hardwood forests. The most recent HTIRC Annual Report is now available and includes research, personnel and outreach news:

• NSF Center for Advanced Forestry System Updates, the only forestry-based National Science Foundation (NSF) Industry/University Cooperative Research Center (I/UCRC)
• Funded Research Grants which includes Backpack System for High Resolution Forest Inventory, Testing Efficacy of Enrichment Plantings for Stand Regeneration in Hardwood Forests, Better Black Walnut by Breeding Without Breeding and much more.
• Creating a Directory, Depository and Database for Historical Genetic and Tree Improvement Trials
• HTIRC Partners with Tree Pro to Distribute Hardwood Seedlings
• Institute of Digital Forestry
• 2024 Tree Improvement Report

If you would like to subscribe and receive the e-newsletter visit HTIRC e-Newsletter.

The mission of the HTIRC is to advance the science and application of tree improvement, management, and protection of hardwood forests, with emphasis in the Central Hardwood Forest Region (CHFR). They seek to develop research and technology-transfer programs that provide knowledge focused on the establishment and maintenance of sustainable, genetically diverse native forests and the development of highly productive woodlands that provide a wide array of products and services.

Other resources:
Forestry & Natural Resources
Tropical HTIRC
An Introduction to Trees of Indiana, The Education Store, Purdue Extension resource center
Native Trees of the Midwest, The Education Store
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
ID That Tree, Playlist, Subscribe to Purdue Extension – Forestry and Natural Resources YouTube Channel
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store
Finding help from a professional forester, Indiana Forestry & Woodland Owners Association
District Forester, Indiana DNR Division of Forestry, for over 10 acres of woodlands
Directory of Professional Foresters, Indiana Forestry & Woodland Owners Association (IFWOA)

Matthew Ginzel, Professor and Director of HTIRC
Purdue Entomology
Purdue University Department of Forestry and Natural Resources
Hardwood Tree Improvement and Regeneration Center (HTIRC)

Congratulations to Liz Jackson, FNR Extension Specialist, on receiving the 2025 Indiana Hardwood Lumbermen’s Association (IHLA) President’s Award. This award is given for exceptional contribution to the forest products industry and to members of IHL. We are proud to celebrate her achievements along with seeing her featured in the April 2025 edition of the Agriculture & Natural Resources (ANR) newsletter.

Liz presenting an award plaque at a Walnut Council national conference.

Agricultural & Natural Resources (ANR) Newsletter: Liz has worked as an Extension specialist associated with three forestry organizations since March 2004. Liz obtained her BS in forest products (’82) from Purdue’s Forestry & Natural Resources Department and MS in business management (’84) from Krannert School of Business under a special forestry/business master’s program.

Before coming to Purdue Extension, Liz spent 15 years in wood products manufacturing as a plant manager at Aristokraft cabinets (now MasterBrand) and purchasing and inventory control manager at Lafayette Venetian Blind.

Liz’s Extension role is to provide programs and products on sustainable forest management and forest stewardship to address woodland owners’ concerns and needs. While representing the Department of Forestry and Natural Resources, she works on behalf of three organizations.

The Hardwood Tree Improvement and Regeneration Center (HTIRC) is a research partnership between Purdue FNR and the USDA Forest Service focusing on management, protection and improvement of fine hardwood species. For the HTIRC she coordinates annual meetings, research conferences and educational programs.

Liz presents on forest management to a group of schoolchildren at Martell Forest.

For the Indiana Forestry & Woodland Owners Association (IFWOA) and National Walnut Council, she represents the interests of the members and manages all business of the associations, including board meetings, annual conferences and education programs, membership and finances, and communications, including newsletters, websites and social media.

Liz is involved in many partnerships around the state, including as a member of the Extension Invasive Species Working Group, on the editorial board for Indiana Woodland Steward newsletter, member of NRCS state technical committee, and advisory partner with Indiana DNR Division of Forestry Forest Stewardship Committee, Sentinel Landscapes, and Let the Sun Shine In Indiana programs.

A highlight of her career was traveling to Washington, D.C., in 2005 to see Sen. Richard Lugar of Indiana and representatives from HTIRC and Indiana forestry plant an Indiana walnut tree on the U.S. Capitol grounds. Ten years later she returned to the site and was thrilled to find the tree and see it was thriving.

Resources:
Indiana Forestry & Woodland Owners Association (IFWOA) YouTube Channel
Observing Seasonal Changes in Nature Webinar with Amanda Wanless, IFWOA YouTube Channel
Magnificent Trees of Indiana Webinar with Author Carroll Ritter, IFWOA YouTube Channel
Ask the FNR Expert: Pests in your Woods, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel
Directory of Professional Foresters, Indiana Forestry & Woodland Owners Association (IFWOA)
Indiana Woodland Steward E-newsletters, Eleven Member Organization
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Invasive Plant Species Identification, Video, Purdue Extension – FNR YouTube Channel
Subscribe – Purdue Extension-FNR YouTube Channel

Agricultural & Natural Resources (ANR), Purdue Extension

Join Purdue Extension forester Lenny Farlee in this episode of “A Woodland Management Moment” as he explores the unique ecosystem of bottomlands. These flat, moisture-rich environments are home to a diverse array of species, shrubs, and trees. Watch the video to discover the key features and characteristics of these fascinating sites.

If you have any questions regarding trees, forests, wildlife, wood products, or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources:
A Woodland Management Moment, Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
The Nature of Oaks Webinar, Purdue Extension-FNR YouTube Channel, Shared from Indiana Forestry & Woodland Owners Association
Conservation Tree Planting: Steps to Success, Purdue Extension – FNR YouTube Channel
Shrubs and Woody Vines of Indiana and the Midwest, Purdue University Press
Native Trees of the Midwest, Purdue University Press
ID That Tree, Playlist, Purdue Extension – FNR YouTube Channel
Investing in Indiana Woodlands, The Education Store
Woodland Stewardship for Landowners Video Series, Playlist, Indiana Department of Natural Resources YouTube Channel
Ask an Expert: Tree Selection and Planting, Purdue Extension – FNR YouTube Channel
Forest Improvement Handbook, The Education Store
Find an Indiana Professional Forester, Indiana Forestry & Woodland Owners Association (IFWOA)
Purdue Arboretum Explorer

Lenny Farlee, Extension Forester
Hardwood Tree Improvement and Regeneration Center
Purdue Department of Forestry & Natural Resources

Purdue Landscape Report: These oak trees are showing the symptoms of smooth patch ( see below Figures 1, 2, 3).  This condition is the result of a fungal infection that is restricted to the outer bark, causing it to slough off. The bark layer remaining is smoother and lighter in color than uninfected, normal bark.

Patches can vary from a few inches to a foot or more in diameter and may occur on branches as well as the trunk.  Several fungi can cause this condition. A common species, Aleurodiscus oakesii, produces clusters of flat, disc-like spore-bearing structures on the surface of the smooth bark. These structures are gray or beige in color and are usually less than 1⁄2 inch in diameter (Figure 4).

The best time to see this interesting phenomenon in the forest is during wet periods in late winter before new spring growth begins, when the light gray bark stands out in the light penetrating the canopy. The fungal structures shrink when dry so will be more apparent following rainy weather.

The fungal structures may be mistaken for wood decay fungi, but because smooth patch fungi invade only the nonliving, outer bark tissues, they do not affect the health of the tree. No control measures are needed.

The fungal structures may be mistaken for wood decay fungi, but because smooth patch fungi invade only the nonliving, outer bark tissues, they do not affect the health of the tree. No control measures are needed.

Resources:
Indiana Forestry & Woodland Owners Association (IFWOA) YouTube Channel
District Forester, Indiana DNR Division of Forestry, for over 10 acres of woodlands
Directory of Professional Foresters, Indiana Forestry & Woodland Owners Association (IFWOA)
Indiana Woodland Steward E-newsletters, Eleven Member Organization
The Nature of Oaks Webinar, Purdue Extension-FNR YouTube Channel, Shared from Indiana Forestry & Woodland Owners Association
Purdue Arboretum Explorer
Native Trees of the Midwest, Purdue University Press
A Woodland Management Moment, Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Conservation Tree Planting: Steps to Success, Purdue Extension – FNR YouTube Channel
Forest Improvement Handbook, The Education Store
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel
ID That Tree – Video Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Invasive Plant Species Identification, Video, Purdue Extension – FNR YouTube Channel
Report Invasive Species, Purdue Invasive Species
Subscribe – Purdue Extension-FNR YouTube Channel

Tom Creswell, Plant & Pest Diagnostic Laboratory Director
Purdue Botany and Plant Pathology

Welcome to “ID That Tree.” In this edition, Purdue Extension Forester Lenny Farlee introduces us to an autumn olive shrub found across Indiana. This dense shrub requires extensive control and management due to its effects on the habitat. Watch the video to learn about its aggressive growth, wildlife impact, leaf pattern, and other features!

If you have any questions regarding wildlife, trees, forest management, wood products, natural resource planning or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources:
ID That Tree – Video Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Purdue Arboretum Explorer
Conservation Tree Planting: Steps to Success, Purdue Extension – FNR YouTube Channel
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Report Invasive, Purdue Extension
Fifty Common Trees of Indiana, Purdue Extension – FNR
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
Native Trees of the Midwest, The Education Store
Professional Forester, Indiana Forestry Woodland Owners Association
Forest Improvement Handbook, The Education Store
Find an Arborist, International Society of Arboriculture

Lenny Farlee, Extension Forester
Hardwood Tree Improvement and Regeneration Center
Purdue Department of Forestry & Natural Resources

Welcome to ID That Tree! In this video, Purdue forester Lenny Farlee examines one of Indiana’s most troublesome invasive shrubs: Amur honeysuckle. This aggressive species, along with other Asian honeysuckle varieties, is widespread across the state. It’s easily identified by its long, pointed leaves, smooth edges, and fine fuzz. Watch the video to learn more about its distinguishing features and the impact on Indiana’s ecosystems!

If you have any questions regarding wildlife, trees, forest management, wood products, natural resource planning or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources:
ID That Tree – Video Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Purdue Arboretum Explorer
Conservation Tree Planting: Steps to Success, Purdue Extension – FNR YouTube Channel
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Report Invasive, Purdue Extension
Fifty Common Trees of Indiana, Purdue Extension – FNR
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
Native Trees of the Midwest, The Education Store
Professional Forester, Indiana Forestry Woodland Owners Association
Forest Improvement Handbook, The Education Store
Find an Arborist, International Society of Arboriculture

Lenny Farlee, Extension Forester
Hardwood Tree Improvement and Regeneration Center
Purdue Department of Forestry & Natural Resources