Got Nature? Blog

Join Purdue Extension urban forester Lindsey Purcell, exotic forest pest educator Elizabeth Barnes and entomology extension specialist Cliff Sadof as they share about how to inspect trees, what to look for, who to contact, etc., as well what invasive pests and diseases you should keep your eye out for.

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.

Ask an Expert, Playlist, Purdue Extension – Forestry and Natural Resources Youtube Channel
Tree Risk Management, The Education Store, Purdue Extension resource center
Tree Appraisal and the Value of Trees, The Educational Store
Surface Root Syndrome, The Education Store
Iron Chlorosis of Trees and Shrubs, The Education Store
Facebook Live – Ask The Expert: Pests in Your Woods, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Fall webworms: Should you manage them, Got Nature? Blog
How to Identify Tree Defects and What to Do about It?, Got Nature? Blog

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

Elizabeth Barnes, Exotic Forest Pest Educator
Purdue University, Department of Entomology

Cliff Sadof, Professor / Ornamental / Pest Management / Coordinator of Extension
Purdue University, Department of Entomology

Posted on September 29th, 2020 in Disease, Forestry, How To, Plants, Urban Forestry, Woodlands | No Comments »

Purdue Landscape Report: Trees are incredible survivors in spite of the challenges from pests of all kinds, including us! They are vulnerable to injuries such as mechanical wounds from lawn equipment, vehicles and ice. Pruning results in an intentional wound which is of importance to consider. Tree owners and managers need to prune trees to maintain aesthetic characteristics, remove infected limbs, reduce risk, or improve structural stability. Proper pruning practice and understanding tree wounds can minimize the impact of creating wounds on trees.

Wounds attract pests due to the phytochemicals dispersed from exposed tissue. When tree tissue is damaged or wounded, the newly uncovered tissue is exposed and that is when to expect an attack. Insect pests are drawn to trees in distress, feeding on the tissue and weakening the tree. Diseases affecting trees will introduce enzymes into the cells, digesting living tissue responsible for food and water translocation (phloem and xylem) or structural support resulting in unhealthy, unsightly, or unsafe trees.

Wound wood Formation
Trees attempt to close wounds by sealing or compartmentalizing the affected area, naturally.


Tree trunk damaged by construction equipment developing wound wood around the edges to eventually seal the wound.

callus tissue

Pruning cuts will develop callus tissue on the exposed tissue giving rise to wound wood.

Wounding of trees during the growing season results in the formation of callus tissue which develops over the wound surface or parts of it. This callus tissue is an unorganized group of important parenchyma cells. As the callus develops and grows, wound wood develops which hopefully will cover the exposed tissue quickly and efficiently.

Wound recovery rates vary widely for different tree species. The speed of recuperation is greatly affected by developmental environmental conditions, vigor and health of the tree. Some trees may never completely close their wounds due to their genetic capacity or perhaps inadequate resources to keep the tree vigorous. However, numerous studies reveal that faster wound closure results in fewer health issues for the tree. Quick healing is always better!

A healthy tree will seal wounds faster and the same for younger trees as well. Trees that are planted in well-drained, quality soils, with good texture, structure, and containing adequate nutrition levels, grow in a way that favors the healing process. Thus, when planting trees, homeowners should be aware of the effects of site selection, soil quality, and other site factors that may impact tree growth.

Wound dressings

Wound dressings slow closure and can prevent healing.


Complete wound closure improves tree health and slows decay.

Faster closure
There are few ways wound closure can be hastened, or at least not inhibited. First, it is essential to avoid limiting oxygen availability to the wounded tissues. Oxygen is necessary for proper recovery. For example, painting a wound with any kind of material that interferes or impedes oxygen will slow or even prevent wound closure by poor callus formation. Wound treatment with petroleum-based products is not recommended. In fact, research indicates any type of wound dressing can slow the healing process. There is one exception for treating wounds. This is in areas where oak wilt disease occurs, wound paints may be useful in preventing insect spread of the oak wilt fungal pathogen.

Basically, the best way to help insure proper wound closure and quick and effective sealing of the tissue is a proper pruning cut and preventing damage whenever possible.

Find a professional
Be sure to always hire an insured, tree care professional, preferably and ISA Certified Arborist with the experience, expertise, and equipment to provide proper tree care. Require proof of liability insurance to protect yourself as well.

Another easy way to find a tree care service provider in your area is to use the “Locate Your Local Tree Care Industry Association Member Companies” program. For more information refer to the publication Trees and Utilities at the Purdue Education Store.

Find an ISA Certified Arborist in your area by visiting the Trees Are Good website.

Tree Pruning Essentials, Publication & Video, The Education Store, Purdue Extension resource center
Tree Pruning: What Do Trees Think?, The Education Store
Mechanical Damage to Trees: Mowing and Maintenance Equipment, The Education Store
Tree Installation Process and Practices, The Education Store
Tree Pruning for the Landscape, Webinar, Purdue Extension – Forestry and Natural Resources Youtube channel

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

Posted on September 23rd, 2020 in Disease, How To, Safety, Wildlife | No Comments »

deerSeptember IDNR Wildlife Bulletin Newsletter: Indiana DNR is conducting targeted surveillance for chronic wasting disease (CWD) surveillance in northwest and northeast Indiana during the 2020-21 deer hunting season. Hunters may voluntarily submit samples for testing at select fish & wildlife areas (FWAs) and state fish hatcheries (SFHs) throughout the hunting season. Deer heads can be dropped into designated coolers at select FWAs and SFHs or hunters may make an appointment for their harvested deer to be sampled by a biologist during office hours. The 2020-21 sampling locations and their hours of operation are listed on the website. Indiana DNR biologists will intensively sample hunter-harvested deer at local businesses in the surveillance areas during three weekends: Nov. 7-8, 14-15, and 21-22.

Hunters interested in testing a deer for CWD that was harvested outside the CWD surveillance areas may take their deer to select FWAs and SFHs as well. Alternatively, hunters may independently submit their deer to the Purdue Animal Disease Diagnostic Lab (ADDL) for testing for a fee. Hunters should complete the submission form and follow the shipping instructions on Purdue ADDL’s website.

Hunters who submit a deer for CWD testing will receive a Deer Management Partner magnet and metal tag reminiscent of Indiana’s historical deer harvest confirmation process.

For more information, please visit the Indiana Department of Natural Resources website.

Chronic Wasting Disease (CWD), Indiana Department of Natural Resouces (IDNR)
New Indiana Hunting & Trapping Guide, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Wildlife Habitat Hint: Trail Camera Tips and Tricks, Got Nature? Blog
Bovine Tuberculosis in Wild White-tailed Deer, The Education Store, Purdue Extension resource center
Indiana Deer Hunting, Biology and Management Food Safety & Handling Take-Home Tips (80kb pdf), Indiana Department of Natural Resources (IDNR)
Handling Harvested Game: Episode 1, Field Dressing, Video, Purdue Extension Youtube channel
Handling Harvested Game: Episode 2, Hanging & Skinning, Video
Handling Harvested Game: Episode 3, Deboning, Video
Handling Harvested Game: Episode 4, Cutting, Grinding & Packaging, Video

Indiana Department of Natural Resources (IDNR)

Tree with drought stress.Many homeowners are finding their trees with dry and wilted leaves and no rain in sight. Urban Forestry Specialist Lindsey Purcell describes how homeowners can deal with these drought-stressed trees in his publication Drought? Don’t Forget the Trees!

Drought can have a major impact on tree health and survival. Water is the most limiting ecological resource for a tree, and without adequate moisture, decline and death are imminent. It reduces carbohydrate production, significantly lowering energy reserves and production of defense chemicals in the tree.

Trees in a weakened state from drought are more susceptible to pests, which can further weaken the tree, and even kill part or all of it. Although there is nothing we can do to prevent drought, it is important to know what can be done to reduce long-term effects of prolonged dry conditions.

Trees in Times of Drought​, Video, Purdue Agriculture
Drought Information, Purdue Extension
Drought Information​, Indiana Department of Natural Resources
Tree Planting Part 1: Choosing a Tree video, Purdue Extension-Forestry and Natural Resources YouTube Channel

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


Brown or black spots with yellowing are signs of anthracnose.

This time of year, many black walnut trees’ leaves may have black spots, turn yellow and begin to drop. This is commonly known as anthracnose, a fungal disease that causes trees to drop their leaves prematurely.

Anthracnose is worsened by wet weather, and some trees are more genetically susceptible to anthracnose than others. It is not fatal but can look like a serious problem. The absence of leaves can slow a tree’s growth and can reduce the nut crop, although by this time of year growth may have slowed or stopped for the season.

Anthracnose generally begins as small circular brown to black areas on the leaflets. Over the season those spots expand and cause leaf drop. There are a few other leaf spot diseases of black walnut, see the references below for descriptions of those diseases.

Although unsightly, there is no need for further action if you are growing timber and have anthracnose in a plantation or woods. It can be an issue if you are growing walnuts for a nut crop, and there are resources and spray products to help manage the fungus in those situations.

If you have individual landscaping trees and want to limit anthracnose spread there are few things you can do:

  • Gather fallen leaves and compost or remove them from the site.
  • Control weeds which could carry the fungus.
  • Plant walnut trees where there is good air circulation.
  • Keep the trees healthy and vigorous by managing soil fertility and thinning competition as needed.

Walnut Anthracnose, Walnut Notes, U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station
Indiana Walnut Council, Industry Representatives include 45 states and 3 foreign countries
Diseases in Hardwood Tree Plantings, The Education Store, Purdue Extension resource center
Planting Hardwood Seedlings in the Central Hardwood Region, The Education Store
Regenerating Hardwoods in the Central Hardwood Region:  Soils, The Education Store
Fertilizing, Pruning, and Thinning Hardwood Plantations, The Education Store
Weed Competition Control in Hardwood Plantations, The Education Store
Resources and Assistance Available for Planting Hardwood Seedlings, The Education Store

Liz Jackson, Manager Walnut Council / IN Forestry Woodland Owners Association (IFWOA) & Engage Specialist
Purdue University Department of Forestry and Natural Resources

Purdue Extension forester Lenny Farlee tells you where to find and how to identify a species that clings to many of our trees, poison ivy. Protect yourself from the itch by recognizing this species before it is a problem.

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.

Poison Ivy, Purdue Landscape Report
Poison Ivy, Purdue Extension
Poison Ivy, The Education Store, Purdue Extension resource center
Investing in Indiana Woodlands, The Education Store, Purdue Extension resource center
Tree Appraisal and the Value of Trees, The Education Store
Forest Improvement Handbook, The Education Store
ID That Tree, Playlist, Purdue Extension – Forestry and Natural Resources Youtube Channel
A Woodland Management Moment, Playlist, Purdue Extension – Forestry and Natural Resources Youtube Channel

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

Purdue Landscape Report: Hot, dry summers are not that unusual in the Midwest, but 2020’s hot dry spell started considerably earlier than usual, before summer even officially began! To make it a triple whammy, the hard freeze in early May caused some landscape plants to burn up more stored carbohydrate reserves to produce a second round of foliage.

(Figure 2) July Heat Map

(Figure 2) July Heat Map

I’m sure I don’t have to point out that most of Indiana is currently experiencing abnormally hot, dry conditions. Although recent rains have brought relief to some areas, any respite is sure to be temporary. Seasonal thunderstorms may deluge some landscapes with water while other areas, even those close by, may stay fairly dry. Much of the area has experienced highs in the upper 80’s to over 90º F over the past month.

Leaf scorch on trees and shrubs, appearing as a browning along the edges of the leaves, is very common in dry summers. While minor cases of leaf scorch are not very harmful, prolonged lack of moisture can spell disaster for landscape plants.

Leaf Scorch on Lilac

Leaf Scorch on Lilac

Hydrangea wilting

Hydrangea wilting

Young and newly established plants are most susceptible to the dry conditions, but even established plants may reach a critical point during prolonged drought. If the heat and drought continue this summer, branch dieback, combined with eventual root death, will make plants more susceptible to winter injury. Plants that were already under stress from other factors may succumb to severely dry soils.

The intense heat makes it difficult for plants to keep up with water and cooling requirements, even in areas where moisture is adequate. One of the ways that plants cool themselves is through transpiration, which allows water to evaporate from the foliage. Plant leaves have pores called stomata that can open and close to allow water vapor and gas exchange with the environment. During extreme heat and/or drought, stomata will nearly close, thus reducing transpiration and exchange of carbon dioxide and oxygen. The end result is seen as wilting foliage and leaf scorch. But not so obvious is that reduced water uptake and gas exchange also leads to reduced production of carbohydrates through photosynthesis and reduced uptake of soil nutrients, having longer term impact on plant health.

There is still plenty of summer yet to get through to see the further challenges ahead. Meanwhile, we can mitigate some of the stress by watering landscape plants as needed where feasible.

US Drought Monitor
Indiana – Purdue Rural Emergency Preparedness, Purdue Extension website
In Times of Drought, Indiana Yard and Garden, Purdue Consumer Horticulture
Drought? Don’t Forget the Trees, The Education Store, Purdue Extension resource center
Turfgrass Disease Profiles: Summer Patch, The Education Store
Iron Chlorosis of Trees and Shrubs, The Education Store

, Extension Consumer Horticulturist
Purdue University Department of Horticulture and Landscape Architecture

Welcome to the Nature of Teaching Professional Development Webinar Series: Ecotoxicology Part 1. This webinar shared by Rod Williams, a professor and extension wildlife specialist with Purdue University Extension, and Jason Hoverman, an associate professor at Purdue University and a co-author on the unit on ecotoxicology, discusses the principles of ecotoxicology, contaminants, and threats to the freshwater ecosystems.

This webinar shares the resources teachers, and K-12 leaders, need to teach students about ecotoxicology. This state standard curriculum includes free downloads of posters, photos, charts, data sheets, and fun activities along with the opportunity to receive a Certificate of Completion

The Nature of Teaching: Ecotoxicology and Environmental Health, The Education Store, Purdue Extension resource center
Benefits of Connecting with Nature, The Education Store
The Nature of Teaching: Disease Ecology, The Education Store
Resourceful Animal Relationships, The Education Store
The Nature of Teaching, Youtube Channel
Nature of Teaching, Website

Rod Williams, Professor of Wildlife Science
Purdue University Department of Forestry and Natural Resources

Jason Hoverman, Associate Professor Vertebrate Ecology
Purdue University Department of Forestry and Natural Resources

Figure 1. White oak slime flux

Figure 1. White oak slime flux

Purdue Landscape Report: Slime flux (also known as wet wood) is a dark, foul-smelling and unsightly seepage of sap from tree trunks (fig. 1). The disease is not usually a serious problem but the appearance can be alarming. Slime flux is caused by common surface-inhabiting bacteria or yeast fungi that enter the trunk through wounds associated with improper pruning, stem breakage, injections, cracks from freeze injury or weak limb crotches. The bacteria and yeast may live on sap nutrients within injured trees for many years without any outward evidence.

The main symptom is the appearance of the dark sap oozing on the trunk exterior which happens when gasses produced by growth of the bacteria and yeast cause the internal pressure of the sap to become high enough to force the sap out through cracks in the bark. The dark streaks usually turn light gray or white upon drying. Oozing sap may be frothy and white at the point of exit. Airborne bacteria, yeasts, and fungi often colonize the wet oozing material, which ferments and releases a foul odor. Slime flux may delay wound healing (callus formation).

Slime flux is extremely common on mature elms (fig 2), oak (fig 3) and mulberry; and is seen less frequently on maples (fig 4), paper birch, sycamore, and walnut.

Figure 4. Silver Maple

Figure 4. Silver Maple

Figure 3. White Oak

Figure 3. White Oak

Figure 2. American Elm

Figure 2. American Elm

There is no control or treatment for slime flux. Inserting a drain tube into the tree to relieve pressure and drain infected sap was once an accepted treatment, but is no longer recommended and may do more harm than good. Boring holes in affected trees causes internal spread of the bacteria within the tree and may allow entry of wood decay fungi.

To reduce the chances of susceptible trees developing wet wood avoid unnecessary wounding of the trunk and branches. Proper pruning techniques, HO-4-W, will allow branches to heal more rapidly. Make sure susceptible trees receive good general care; including irrigation when needed and mulch to conserve moisture and keep mowers away from the trunk. Avoid excess traffic in tree root zone to prevent soil compaction and root injury.

The first and most important step for managing a tree disease is to accurately diagnose the problem. The best approach to diagnosis of tree problems is to start by submitting photos of the tree via the digital upload tool on the Purdue Pest & Diagnostic Lab (PPDL) website. In the case of slime flux it is impractical to collect the type of physical sample needed for confirmation so photos are the best alternative.

Sinclair, W. A. and H. H. Lyon. 2005. Diseases of trees and shrubs. Cornell University Press, Ithaca, NY. 660 pp.
Stipes, R. J. and Campana, R. J. (eds.) 1981. Compendium of Elm Diseases. APS Press, St. Paul, MN.

Diseases in Hardwood Tree Plantings , The Education Store, Purdue Extension resource center
Iron Chlorosis of Trees and Shrubs, The Education Store
Surface Root Syndrome, The Education Store

Tom C Creswell, Clinical Engagement Professor – Plant & Pest Diagnostic Laboratory
Purdue University Department of Botany and Plant Pathology

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

blue spruce needle castQuestion: I have a blue spruce that is 40-years old and very tall. It is dying up the middle. I have read about the Needle Cast problem. Also read about Spectro 90 copper based fungus control. I can only spray so high. Is there a chemical that can be placed on the ground to be absorbed by the tree?

Answer: Thank you for contacting us regarding your tree issues. Rhizosphaera needle cast (Rhizosphaera kalkhoffii) is a foliar disease of spruce trees. It is most common in trees growing outside of their native range. It starts on the inner and lower growth and progresses upward through the tree. It can take up to 15 months for the needles to show visible symptoms after the initial infection. Young trees may be killed by this disease, but usually branches die off after 3-4 consecutive years of defoliation, causing trees to look disfigured.

Early identification of Rhizosphaera can prevent major damage to individual trees and prevent the spread to nearby trees. Protecting new growth as it emerges is very important. For best effectiveness, fungicides should be applied when the emerging needles are half elongated (1/2 to 2 inches in length). Needle cast diseases can be effectively controlled with fungicides containing chlorothalonil. For Rhizosphaera needle cast, two properly-timed applications per year for at least two consecutive years, and sometimes three years, is required for control. Heavily infected trees may require several years of fungicide applications but should be sprayed, soil drenches are not effective. Also, clean-up of any infected needles and branches will help reduce the spread of the disease.

Needle cast in Colorado Blue Spruce, Purdue Landscape Report
Blue Spruce Update, Purdue Landscape Report
Why Spruce Trees Lose Their Needles, Purdue Extension
Blue Spruce Decline, Purdue Extension
Diseases Common in Blue Spruce, Purdue Extension
Tree Installation: Process and Practices, The Education Store, Purdue Extension resource center
Tree Planting and Urban Forestry Videos, Subscribe to our Purdue Extension-FNR YouTube Channel

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

Got Nature?

Recent Posts