Got Nature? Blog

Purdue Landscape Report: Many trees are planted for their beautiful fall color, especially in locations where the climate provides reliable autumn weather. I have said this multiple times during extension talks and conversations with submitters to the Purdue Pest & Plant Diagnostic Lab (PPDL), but I seem to have not experienced a ‘normal’ fall since moving to Indiana with how erratic the weather has been from year to year. Depending on weather conditions, such as high heat and drought, colors may develop early or may be duller for specific varieties than expected.

However, individual trees that begin to show fall colors earlier than expected (August, September, even early October) may be shouting out a proverbial cry for help. Plants will often show yellow or red foliage coloration during periods of stress, so this may occur at any point during spring, summer, or fall. Individual trees may also show fall coloration earlier than others of their species in the same area.  Now is the time to keep an eye out for this kind of early fall color as it can give you a heads-up on issues you can expect next year.image of early fall color from a tree

When examining a tree with early fall color, I would recommend checking the following:

  • Is there a root flare?
    Purdue Landscape Report: Deep Planting article

    • If not – tree could be planted too deep or the soil grade may have been changed
  • Is there any obvious damage to the trunk, root flare, or surface roots?
    • If so, there could internal decay that is not obvious and could be contributing to stress
  • Are there any girdling roots?
    Purdue Landscape Report: Stem Girdling Roots article

    • If present, they could be affecting the vascular system and strangling the tree
  • Is the rootzone mulched?
    • If not, the tree could be under stress from earlier drought, or weed and grass competition.
    • If so, make sure it is not mounded against the trunk of the tree
  • Does the soil appear compacted? Was there construction near the tree within the last 5 years?
    • Compaction leads to issues with water, nutrient, and even oxygen availability to the roots and could lead to general decline

It is important to know the host species, but with the sheer volume of plant material available for sale in the nursery trade, it is even more important to know the cultivar that you are planting so you know what you might expect coming into the fall.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Why Fall Color is Sometimes a Dud, Purdue Landscape Report
Forest Migration Plays a Role in Fall Foliage Colors, Purdue College of Agriculture News
U.S. Forest Service Fall Colors, Forest Service, U.S. Department of Agriculture
ID That Tree Fall Color: Sugar Maple, Purdue Extension – Forestry and Natural Resources YouTube Channel, ID That Tree Playlist
ID That Tree Fall Color Edition: Black Gum, Purdue Extension – FNR YouTube Channel, ID That Tree Playlist
Autumn Highlights Tour – South Campus, Purdue Arboretum Explorer
Why Leaves Change Color – the Physiological Basis, The Education Store, Purdue Extension resource center
Subscribe, Purdue Extension-Forestry and Natural Resources YouTube Channel
Planting Your Tree Part 1: Choosing Your Tree, Purdue Extension YouTube Channel
Summer Tree Care, Purdue Landscape Report
Tree Defect Identification, The Education Store
Tree Wound and Healing, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Surface Root Syndrome, The Education Store
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
Ask an Expert: Tree Selection and Planting, Purdue Extension-Forestry & Natural Resources (FNR) YouTube playlist
ID That Tree, Purdue Extension-FNR YouTube playlist

John Bonkowski, Plant Disease Diagnostician
Departments of Botany & Plant Pathology

Purdue Forestry and Natural Resources’ extension efforts over the past two years amidst the COVID-19 pandemic were recognized in the Purdue Extension Specialist Quarterly newsletter.

Ask an Expert Zoom screen shot as extension specialists share resources and answer questions regarding wildlife, forestry, community planning and invasive species.The transition to virtual content brought expertise across subject matter areas, ranging from forestry and wildlife, to aquatic sciences and entomology, to the masses in the form of several video series which collectively earned nearly 150,000 views.

The FNR Extension team included: Jay Beugly, Jarred Brooke, Nick Burgmeier, Barny Dunning, Diana Evans, Lenny Farlee, Jason Hoverman, Liz Jackson, Brian MacGowan, Patrick McGovern, Wendy Mayer, Charlotte Owings, Lindsey Purcell, Bee Redfield, Shelby Royal, Bob Rode, Kara Salazar, Mike Saunders, Amy Shambach, Rod Williams, Mitch Zischke, as well as frequent Entomology contributors: Elizabeth Barnes, Cliff Sadof.

The feature in the fourth quarter newsletter begins:
“While Covid caused limitations on travel and in-person events nationwide, across Indiana, many were spending more time in outdoor recreational activities, hiking, bird-watching, hunting and fishing, or managing natural resources properties. Adjusting to the pandemic, the FNR team created an innovative and team-oriented instruction approach through skill-building in video production with coordinated connection and crosspromotion of resources.

“Forestry and Natural Resources (FNR) faculty, specialists, staff, and students, with invited partners across research and Extension, delivered 45-minute Ask an Expert Facebook Live programs for 35 weeks. Programs covered many FNR specialties: Animals & Insects (bats, bird, cicadas, coyotes, deer, fish, frogs, hellbenders, moles, pollinators, salamanders, snakes, toads, turtles, and wood pests); Plants & Ecosystems (invasive plant species, hardwood ecosystems, native grasses for wildlife, conservation tree planting, rainscaping, fall food plots, and selecting, planting and inspecting trees); and Management & Operations (prescribed fires, aquatic plant and pond management, and fish and wildlife management).

Ask An Expert Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
ID That Tree Playlist, Purdue Extension – FNR YouTube Channel
A Woodland Management Moment Playlist, Purdue Extension – FNR YouTube Channel
Wildlife Habitat Hint Playlist, Purdue Extension – FNR YouTube Channel
Subscribe to the Purdue Extension – Forestry and Natural Resources YouTube Channel

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

Diana Evans, Extension and Web Communication Specialist
Purdue University Department of Forestry and Natural Resources

Purdue Landscape Report sharing resources on spotted lanternfly.The interdisciplinary faculty and staff behind the Purdue Landscape Report, which provides science-based, timely information regarding Midwest landscapes to commercial growers, garden centers, landscapers, arborists and the general public, has been named as the recipient of the Purdue Agriculture TEAM Award, which was created in 1995 to recognize interdisciplinary team achievements of faculty and staff.
Teams must consist of three or more Purdue faculty and administrative/professional staff members. Team projects should include activities in one or more of the College mission areas of teaching, research and extension, and must have made demonstrable impact.

Led by Kyle Daniel, nursery and landscape outreach specialist in the Department of Horticulture and Landscape Architecture, the Purdue Landscape Report is a collaborative effort between Purdue Extension specialists and diagnosticians in the departments of Botany and Plant Pathology, Entomology, Forestry and Natural Resources, and Horticulture and Landscape Architecture. Articles cover everything from urban forestry and tree maintenance to pest and disease problems and management to plant selection and turf science. In addition to an email newsletter and online blog, PLR staff also provide live interactive webinars in order to highlight content and respond to questions from the audience.

“I believe this team embodies the spirit of this award – working together across department in the College,” said Dr. Linda Prokopy, Department Head in Horticulture and Landscape Architecture. “This team has indeed achieved more and is a consistent source of reliable, science-based information for homeowners and the green industry. The PLR team is doing a phenomenal job meeting the needs of an important industry in the state and they are very deserving of being recognized for this work.”
In the nomination for the TEAM Award, the impact of the Purdue Landscape Report team was described as:
“The quality of life and livelihood of many Hoosiers is greatly improved when cities and towns have healthy trees, shrubs, and flower beds. The task of growing and maintaining these plants is complicated by conflicting, incomplete or inaccurate media reports about the arrival of new pests and diseases; or how landscape choices, or use of certain management practices can have a negative impact on the environment and public health. Tree owners, landscapers and the professional workforce need timely science-based information to keep plants healthy in an environmentally sustainable manner.”
Since launching in February 2018, the Purdue Landscape Report has included more than 200 articles. PLR is sent out in a bi-weekly email newsletter to more than 4,000 subscribers nationwide. The online blog brought in 180,376 unique visitors in 2020.

In response to the pandemic, the Purdue Landscape Report staff also began a live, to addresses articles and hot topics. That series garnered more than 2,000 views.
In a January 2021 survey sent to PLR subscribers, 88% of respondents said they believed that the newsletter improved their ability to diagnose a problem, while 76% said that PLR has had a positive economic impact on their business.

A local professional shared that “Sometimes when I open up the PLR, it is like you have been reading my mind. The problem I have been seeing or thinking about is there in your headlines.”

Lindsey Purcell sharing tree planting tips at outside workshop. Purdue Landscape Report receives TEAM award.One PLR subscriber said “The Purdue Landscape Report is a great resource for myself and my team members. Within each issue is one or more topics that our team has encountered or discussed recently and the information provided by a very reputable source gives us the material needed to provide the best service to our clients and increase our knowledge base. The virtual sessions are another great resource provided that give an opportunity to have specific questions answered by experts.”

The impact extends from landowners to industry professionals and beyond.

“Often we take for granted the information produced in the PLR and we forget the countless dollars we have saved from information in the PLR,” said Rick Haggard, Indiana Nursery and Landscape Association Executive Director.

“The Purdue Landscape Report provides timely information to the Indiana Arborist Association members and associated parties in a format that is easily accessed and understood,” Associate Executive Director of IAA Ashley Mulis said. “The collaboration that goes into providing this product demonstrates the cohesive nature of several departments within Purdue University and the open sharing and comparison of information. The Purdue Landscape Report is an excellent addition to the many publications offered within Purdue Extension  in helping resource professionals manage the ever-changing landscape of pests, diseases and best management practices.”

In 2020, the PLR received the Extension Division Education Materials Award for Outstanding Blog presented by the American Society of Horticultural Science and received also earned the Team Award from the Purdue Cooperative Extension Specialists’ Association (PUCESA).
For team list and full article view: Purdue Landscape Report Selected for TEAM Award.
Wendy Mayer, FNR Communications Coordinator
Purdue University Department of Forestry and Natural Resources
Lindsey Purcell, Urban Forestry Specialist
Purdue University Department of Forestry and Natural Resources

Posted on September 1st, 2021 in Alert, Disease, How To, Wildlife | No Comments »

MyDNR Email Newsletter: DNR recently updated its recommendations related to the bird disease outbreak. Based on the data received from reports submitted by Indiana residents, it appears that the bird illness is consistently affecting specific areas. Find which counties are continuing to be affected by this outbreak on our website.Blue jay on bird feeder.

One of the simplest and most effective ways residents can help wild birds is by regularly cleaning bird feeders. Seed and suet feeders should be cleaned at least once every two weeks, and hummingbird feeders should be cleaned at least once a week. Bird feeders can be a breeding ground for disease if not properly cleaned. Help your feathered visitors stay healthy year-round by scrubbing feeders with soap and water, followed by a short soak in a 10% bleach solution.

Full article > > >

Cause of Songbird Deaths Remains a Mystery, Purdue Extension-Forestry and Natural Resources, Got Nature? Blog
Birdfeeder tips, The National Audubon Society
Birds and Residential Window Strikes: Tips for Prevention, The Education Store, Purdue Extension resource center
Breeding Birds and Forest Management: the Hardwood Ecosystem Experiment and the Central Hardwoods Region, The Education Store
Managing Woodlands for Birds Video, Purdue Extension-Forestry and Natural Resources YouTube Channel

Indiana Department of Natural Resources

Posted on June 30th, 2021 in Alert, Disease, Wildlife | No Comments »

Starting in May, the Indiana Department of Natural Resources (DNR) began to receive reports of sick and dying songbirds from several counties around the state. As of now, the cause of the illness remains a mystery although submitted specimens have tested negative for avian influenza and West Nile virus according to the DNR. Affected birds have white crust and discharge around the eyes and damage to their nervous system. Reports of sick birds have expanded to many more counties in Indiana.

Several diseases that affect songbirds are transmitted from one animal to another. Bird feeders can increase the likelihood of disease transmission by facilitating close contact among birds. Even though the disease and its mode of transmission in this case is unknown, the DNR is recommending all Hoosiers remove their birdfeeders.

Blue jay on bird feeder.Officials recommend the following steps:

  • Use the DNR sick/dead wildlife reporting tool at to alert DNR staff.
  • Stop feeding birds until the mortality event has concluded.
  • Clean feeders and baths with a 10% bleach solution.
  • Avoid handling birds. If you need to handle birds, wear disposable gloves.
  • When removing dead birds, wear disposable gloves and place birds and gloves in a sealable plastic bag to dispose with household trash.
  • Keep pets away from sick or dead birds as a precaution.
  • Proper care of bird feeders and seed is an important part of preventing disease transmission at birdfeeders.

The Audubon Society recommends the following best practices:

  • Clean feeders monthly using one part bleach to nine parts warm water. Soak the feeder in the solution for a few minutes, rinse, and air dry.
  • If uneaten food is accumulating in or under feeders, consider using less food or switch to a seed more to the birds’ liking.
  • If birds are fighting over space at a feeder, consider adding more feeders to alleviate the congestion that can potentially be responsible for the rapid spread of disease.
  • Avoid throwing large amounts of food on the ground or alternate ground feeding areas so that uneaten food does not accumulate and develop bacteria or mold.

DNR recommends removal of birdfeeders statewide – June 25, Indiana Department of Natural Resources
Birdfeeder tips, The National Audubon Society
Birds and Residential Window Strikes: Tips for Prevention, The Education Store, Purdue Extension resource center
Breeding Birds and Forest Management: the Hardwood Ecosystem Experiment and the Central Hardwoods Region, The Education Store
Managing Woodlands for Birds Video, Purdue Extension-Forestry and Natural Resources YouTube Channel

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

Posted on June 14th, 2021 in Disease, Forestry, Gardening, Plants, Urban Forestry | No Comments »

Purdue Landscape Report: While fungi are responsible for many of our foliar disease problems, different fungal pathogens present as problems throughout the country, depending upon the host plant grown and the environmental conditions. This is a brief overview of several common types of fungal leaf diseases that occur in Indiana and throughout North America (and Europe). Recognizing the symptoms and signs is an important first step to diagnose a disease problem, followed by how to manage these diseases by combining cultural and chemical controls.

Common fungal leaf diseases of deciduous trees and shrubs

Anthracnose Example Photo

Figure 1. Anthracnose is a yearly problem on sycamore in the Midwest. Photo by Janna Beckerman.

Anthracnose. Anthracnose diseases probably are the best-known foliar fungal diseases of deciduous trees. They affect many ornamental trees including major shade-tree genera such as sycamore (Platanus spp.), oak (Quercus spp.), maple (Acer spp.), elm (Ulmus spp.) and ash (Fraxinus spp.) (Fig. 1). Anthracnose actually is a general term describing symptoms such as dead irregular areas that form along and between the main vein of the leaf. The leaves may also become curled and distorted and twigs may die back. The fungus overwinters in infected twigs and the petioles of fallen leaves, and the spores disseminate in the spring by wind and splashing rain. The disease, while unsightly, rarely results in the tree’s death. Sycamores and other trees often withstand many years of partial defoliation. However, one anthracnose disease is more serious. Dogwood anthracnose (Discula destructiva) is a devastating problem on the Eastern seaboard, but has not been a significant issue here in Indiana.

Leaf blister example photo

Figure 2. Leaf blister on oak. Photo by Janna Beckerman

Leaf blisters result in the blistering, curling and puckering of leaf tissue. Oak leaf blister (Taphrina caerulescens) is a common blister disease of oaks (Fig. 2)., particularly the red oak subgenus, which includes Northern red oak (Q. rubra) and pin oak (Q. palustris) among others. The symptoms begin as a slight yellowing of the infected leaf followed by round, raised blisters. These turn brown, and the infected leaves fall prematurely. This fungus overwinters as spores on the buds.

Leaf spot is a general symptom caused by a multitude of pathogens and infect all deciduous trees and shrubs, and include dead spots with a defined boundary between living and dead tissue. The dead tissue often separates from the surrounding living tissue creating a “shot-hole” appearance on the infected leaves. Common hosts include dogwood, maples, hydrangea, rose, holly, and Indian-hawthorn.

Tar Spot Example Photo

Figure 3. Tar spot is increasing in incidence and severity in Indiana. Photo by Janna Beckerman.

Tar spot (Rhytisma spp.) is a leaf disease with initial symptoms similar to leaf spot. The disease is most common on red (Acer rubrum) and silver maple (A. saccharinum) (Fig.3), but it can occur on a wide range of maple species from sugar (A. saccharum) and Norway (A. platanoides) to bigleaf maple (A. macrophyllum). The symptoms begin in the spring as small greenish-yellow spots on the upper leaf surface that, by mid-summer, progress to black tar-like spots about 0.5 inch in size. The disease is not fatal to the tree, but the appearance of the tar spots alarms some tree owners. A major outbreak in New York about 10 years ago left many maples completely defoliated by mid-August.

Full Article >>>

Diplodia Tip Blight of Two-Needle Pines, The Education Store, Purdue Extension resource center
Boxwood Blight, The Education Store
Disease of Landscape Plants: Cedar Apple and Related Rusts on Landscape Plants, The Education Store
Planting Your Tree Part 1: Choosing Your Tree, Purdue Extension YouTube Channel
Tree Planting Part 2: Planting a Tree, Purdue Extension YouTube Channel
Purdue Landscape Report

Janna Beckerman, Professor of Plant Pathology
Purdue Department of Botany and Plant Pathology

Purdue Landscape Report: We receive a large number of spruce samples each year at the Purdue Plant and Pest Diagnostic Laboratory (PPDL), with the vast majority being from Colorado blue spruce with needlecast. Many others show lower needle yellowing, which could be associated with nutrient deficiency or root stress.

Figure 2: A young spruce tree under the effects of transplant and root stress.


Figure 1: A spruce tree suffering from root damage and water stress.

However we are receiving an increasing number of Norway spruce samples with small branch dieback from the tips. This tip dieback symptom can have many causes: cold injury, root damage manifesting in branch dieback, Diplodia tip blight (caused by Diplodia sapinea, the same pathogen that causes tip blight in pine), and Cytospora canker. Phomopsis, another fungal pathogen which causes tip blight on spruce in nursery situations has been observed in greater frequency since 2012 by plant diagnostic labs in the North Central region causing cankers and tip dieback in more mature spruce trees in the landscape.

Figure 4: Phomopsis dieback with excessive needle loss on branch tips.


Figure 3: Dieback symptoms in a mature tree associated with Phomopsis infection.

The disease begins in the lower canopy and moves upward, but in some cases it progresses quickly, causing dieback through a large portion of the tree. Besides needle death and drop, there are virtually no other external symptoms to indicate where the original infection took place. Occasionally you may find resin building on the outside of a canker. Cutting into the thin bark will show the brown discolored tissue where the canker is developing. Cankers are often located in between two areas of healthy tissue. This can lead to older needle loss similar to needlecast diseases, but leaving terminal buds alive. However, once the pathogen spreads and girdles the branch, the rest of the branch will begin to die out to the tip.

For full article >>>

Borers of Pines and Other Needle Bearing Evergreens in Landscapes, The Education Store, Purdue Extension resource center
Ask an Expert Question: Blue Spruce dying, what can I do?, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Why Spruce Trees Lose Their Needles, Purdue Extension
Diseases Common in Blue Spruce, Purdue Extension

John Bonkowski, Plant Disease Diagnostician
Purdue Department of Botany and Plant Pathology

Purdue Landscape Report: When the irises begin to bloom, expect up to 1.5 million cicadas per acre to begin boiling out of the ground. This spring Indiana will see the emergence of the 17-year cicadas (Brood X). These insects feed underground for most of their lives drinking sap from tree roots. Once every 17 years they emerge en masse, climb up trees, sing (though it sounds more like screaming), mate, and lay their eggs on the tips of tree branches. This cycle is completely natural and has a long history in written and oral records. Cicadas are not harmful to humans, provide a feast for wildlife, and mostly only cause cosmetic injury to trees. However, there are some trees that will need protection to survive.


17-year cicadas have much brighter colors than their annual cousins. They can be recognized by their bright red eyes, black bodies, and orange wing veins. Image by John Obermeyer, Purdue Entomology, Purdue University.

Cicada Emergence Timing and Locations
Where can you find cicadas?
17-year cicadas can be found throughout Indiana but the biggest populations will be in southern Indiana. According to Cicada Mania, these cicadas were reported to be more abundant in the following areas during their last emergence in 2004: “Bloomington, Brookville, Clinton Falls, Dillsboro, Fishers, French Lick, Indianapolis, Lawrenceburg, Lexington, Martinsville, McCormick’s Creek State Park, Nashville, North Vernon, Skiles Test Park, Spencer”

Cicadas need to feed on trees nearly constantly for most of their lives. They are therefore typically only found in areas that had trees 17 years ago and have continued to have trees since then. For example, an area that was forest 17 years ago but was cleared for farmland 10 years ago will not have a cicada emergence because the cicadas had no tree roots to feed on for the past 7 years. An area that was farmland 17 years ago and was recently planted with trees will also not have a cicada emergence because there were no trees on which the cicadas laid their eggs. However, a forested area or a city park that has had trees constantly for the last 17 years has a high chance of having a cicada emergence this spring.
When will 17-year cicadas emerge?
Timing of the 17-year cicada emergence depends on temperature. We can therefore expect them to emerge from the southern part of the state several weeks before they emerge in the north. The weather can also have an impact on emergence. For example, a warm spring might make them emerge sooner while a cold spring will delay the emergence. However, in most places the major emergences are expected to start in mid-April and continue through mid-May. A good rule of thumb is to expect the cicadas to emerge around the same time as irises start to bloom. You can also use the emergence calculator to estimate when they will come out in your area.

An example of a heavily damaged full grown tree. The brown, dead leaves are twigs that were killed by cicada egg laying. The damage may look severe, but this tree should recover from the cicada damage by the following year. Image by John Obermeyer, Purdue Entomology, Purdue University.

Cicada Visual ID

What do cicadas look like?
Cicadas tend to have sturdy, thick bodies with mostly clear wings that are longer than their bodies. 17-year cicadas are distinctive from the annual cicadas in that their bodies are a dark, nearly black brown with amber highlights on their wing veins, and red eyes (figure 1). Check out this video to see the full life cycle and hear what a chorus of cicadas sounds like!

How many species of cicadas are there in Indiana?
There are more than you’d think! There are three main species of 17-year cicada in Indiana and about 16 species of annual and 13-year cicadas. You can find a full list here.

Cicada Damage and Control
What do cicadas prefer to eat?
17-year cicadas aren’t picky! They’ll feed on more than 270 species of woody plants. They show a slight preference for deciduous trees like maple, fruit trees, oak, and dogwood, but will generally feed on any deciduous tree or bush available to them.

How do cicadas injure plants?
Cicadas lay eggs by stabbing their ovipositor into tree bark. This can create scars in the bark. If enough cicadas lay eggs on a small branch, it can kill the twig. As a result, large trees sometimes have minor dieback at the ends of branches but overall tree health isn’t affected (figure 2). Small or young trees and shrubs, however, may be more seriously harmed.

What kind of plants should be protected from cicadas?
Cicada females prefer to lay their eggs in branches that are about 3/16 to 1/2 inch in diameter. Therefore, young deciduous trees or bushes that have major branches less than ½ inches in diameter should be protected in areas with high numbers of cicadas emerging. Mature trees do not require protection.


All vulnerable parts of trees should be completely covered. Note how the branches are fully covered by the fine netting and the fabric is tied tightly at the trunk of the tree. Photo by James B Hanson USDA Forest Service.

How should I protect my trees from cicadas?
Homeowners only need to worry if they have newly planted trees (3-4 years old). The best way to protect these young trees is to cover them in a mesh fabric for the ~1 month period when the cicadas are active in the area. The mesh bags can be made from a variety of materials as long as the holes are smaller than 1 cm (~3/8 inch). Drape the fabric over all the twigs and branches that are smaller than 3/8 inches and secure it at the bottom so that cicadas cannot climb up from underneath (figure 3). The goal is to prevent the cicadas from having access to the branches so that they will lay their eggs elsewhere.

Larger trees do not need to be protected from cicadas. They may experience minor dieback at the tips of branches, but this will not harm the overall health of the tree. If you find these dead twigs unsightly, you can either trim them off or hire an arborist to remove them.


Fruit Growers and Nurseries:
 We recommend netting over insecticides. Netting reduces injury by over 95%, while insecticides only reduce injury by 75%. Also, the insecticides that work best against cicadas are likely to kill helpful insects and cause problems with spider mites later in the season. Netting will keep the cicadas off of the trees without running the chance of the negative side effects of insecticides. However, we recognize that for large plantings netting isn’t practical. In these cases, pyrethroid insecticides will need to be applied repeatedly to trees during the ~1 month period when cicadas are active. Make sure to carefully read the labels before using them.
Learn more
The best way to keep up to date about this spring’s cicada emergence is to either sign up for our Cicada Newsletter or follow Purdue Entomology on Twitter or Facebook. We will share updates about the emergence timeline, any updates to management recommendations, community science programs, crafts for kids, and more. If you have any questions, please feel free to reach out to the authors!
Billions of Cicadas Are Coming This Spring; What Does That Mean for Wildlife?, Got Nature? Blog, Purdue Extension-Forestry and Natural Resources (FNR)
17 Ways to Make the Most of the 17-year Cicada Emergence, Purdue College of Agriculture
Ask an Expert: Cicada Emergence Video, Got Nature? Blog, Purdue Extension-FNR
Periodical Cicada in Indiana, The Education Store, Purdue Extension resource center
Cicada Killers, The Education Store
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 January 4th, 2021 in Disease, Forestry, How To, Plants, Publication | No Comments »

FNR-614-WWell-maintained trees provide many benefits including increased property values, improved air quality and curb appeal. Trees are living organisms making them vulnerable to pests and environmental extremes resulting in health issues which result in defects. This publication will help guide you on where and how to identify tree defects and a better understanding of when to contact an arborist for assistance.

Tree wounds and healing, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
How to Identify Tree Defects and What to Do About It?, Got Nature? Blog
Iron Chlorosis of Trees and Shrubs, The Education Store, Purdue Extension resource center
Surface Root Syndrome, The Education store
Tree Appraisal and the Value of Trees, The Education Store

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

Purdue Landscape Report: Tubakia leaf spot, caused by the fungus Tubakia, is the disease we find more commonly on oak than any other. Throughout the world, there are 11 species of Tubakia known to infect oak, with Tubakia dryina (previously known as Actinopelte dryina) being the most commonly encountered species in our landscapes. Apple, ash, black gum, chestnut, elm, maple, and redbud are all reported as hosts of Tubakia species, but oaks are the most frequently and severely affected. Among the oaks, the red oak group, specifically red, pin, and black oaks, are reported to be more susceptible to infection compared to those in the white oak group.


Figure 2: Oak leaf with circular shaped Tubakia leaf spots along with extensive veinal necrosis.


Figure 1: Oak leaf with irregularly shaped Tubakia leaf spots and veinal necrosis.

Leaf spots appear in mid to late summer (July –August) as small circular to irregular tan, red-brown, to dark brown spots (Figure 1, 2) that expand to approximately the size of a dime overtime, but can coalesce, forming large areas of necrotic tissue (Figure 3) . When a spot reaches a leaf vein it expands very quickly, causing a necrotic streak along the vein, and can cause blighting of most of the leaf (Figure 4, 5). Trees under stress from other causes will frequently exhibit more severe leaf spotting compared to healthier trees. Premature defoliation can occur in these situations.

Figure 3: Marginal blighting due to coalescing spots and veinal necrosis.


Figure 5: Blighting of large leaf area caused by veinal infection by Tubakia.


Figure 4: Typical Tubakia leaf spot symptoms illustrating how the fungus spreads along leaf veins.

The pathogen produces conidia within shield shaped structures called pycniothyria (Figure 6) which can be found on both the top or bottom surface of the leaf and along veins (Figure 7). These structures are very small and can only be seen with a 40x or stronger hand lens. The fungus overwinters on fallen leaves and on dead stems which act as the source of inoculum for the next year. During early spring, spores are spread by wind and water splash dispersal (rain) to healthy new foliage. However, it takes time for symptoms to develop throughout the season, depending on tree stress and environmental conditions (warm wet weather favors spread).

For full article view: Purdue Landscape Report, Purdue Landscape Report.

Diseases of Landscape Plants: Leaf Diseases, The Education Store, Purdue Extension resource center
Consumer Horticulture: Fertilizing Woody Plants, The Education Store
Tree Disease; Oak Wilt in Indiana, The Education Store
Diseases of Soybean: Frogeye Leaf Spot, The Education Store
Bur Oak, Purdue Arboretum Explorer
Bur Oak, Native Trees of Indiana River Walk, Purdue Fort Wayne
Find an Arborist,

John Bonkowski, Plant Disease Diagnostician
Purdue Department of Botany and Plant Pathology

Tom C Creswell, Clinical Engagement Professor – PPDL
Purdue Department of Botany and Plant Pathology

Got Nature?

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