Got Nature? Blog

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.

cicadaSideDorsal

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.
cicadaDamage

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.

Covered-trees

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:
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!
Resources
Periodical Cicada in Indiana, The Education Store, Purdue Extension resource center
Cicada Killers, The Education Store
The Year of the Cicada, Purdue Extension
Periodical Cicadas – Unhurried but Reliable Metamorphosis, Purdue Extension
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

In this edition of ID That Tree, Purdue Extension forester Lenny Farlee introduces you to chestnut oak, sometimes called rock chestnut oak. It is an oak species commonly found in the southern part of the state on high dry sites. It has small, very rounded lobed leaves and strongly ridged, very dark bark.

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
Chestnut Oak, Native Trees of Indiana River Walk, Purdue – Fort Wayne
Quercus Montana, The Purdue Arboretum Explorer
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
Investing in Indiana Woodlands, The Education Store
Tree Appraisal and the Value of Trees, The Education Store
Forest Improvement Handbook, The Education Store

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


treeInDec

Surviving winter actually begins in fall when leaves turn color and drop to the ground.

Purdue Landscape Report: So, what do trees do in the winter? Do they freeze up like unprotected water pipes? Or burst when it gets below freezing? Yes, the below-ground parts of a tree are kept insulated by mulch, soil and a layer of snow, and that is important to survival, but the exposed parts of a tree are not protected.

Deciduous trees, like maples and oaks, have a lot of water inside their trunks and branches. Water is the single most important substance for tree life, comprising nearly 80% of tree material. Although there is a little less inside the tree during the winter, if the temperature drops low enough, the water in even the most cold-hardy tree will freeze. Broadleaf, deciduous trees lose their leaves in the winter to reduce water loss inside the trunk and branches. Most needle-leaved trees, known as conifers, which include pines and spruce, retain needles year-round – with exceptions of some deciduous evergreens such as larch and bald cypress– only losing older, or damaged needles. Needles are better at retaining water than broadleaves due to their small surface area and waxy outer coating limiting water loss to transpiration, the evaporation of water from leaves. A hard freeze or poorly timed drop in temperatures can be devastating to living tree cells since ice crystals can shred cell membranes, leading to dead leaves, branches, and even whole trees. Most trees live through the winter despite prolonged exposure to brutally cold air and wind and snow, with special strategies and planning.

Dormancy of trees can be divided arbitrarily into three phases: early rest, winter rest, and after-rest. Each of these phases is marked by a distinct set of physiological processes. The transition between the three phases is gradual and there are many metabolic and developmental processes going on in the buds and twigs. A tree begins its preparations in late summer as day length shortens to survive winter temperatures. Cold acclimation occurs gradually and fall color is a sign that the process is in place and pre-dormancy is beginning.

evergreen

Evergreens are a little different and have a special waxy covering to reduce water loss during the winter.

When the tree enters the winter rest stage, research suggests three basic ways in which a tree prevents freezing. One is to change their membranes, so the membranes become more pliable; this allows water to migrate out of the cells and into the spaces between the cells. The relocated water exerts pressure against the cell walls, but this pressure is offset as cells shrink and occupy less space.

The second way a tree helps prevent freezing is to thicken the fluids within the cells. When days begin to get shorter, trees convert starch to sugars, which act as a natural antifreeze for the plant. The cellular fluid within the living cells becomes concentrated with natural sugars, which lowers the freezing point inside the cells, while the water between the cells is allowed to freeze. Because the cell membranes are more pliable in winter, they’re squeezed but not punctured by the expanding ice crystals.

The third mechanism involves what has been described as a “glass phase,” where the liquid cell contents become so viscous that they appear to be solid, a kind of “molecular suspended animation” and mimic the way silica remains liquid as it is supercooled into glass. This mechanism is triggered by the progressive cellular dehydration that results from the first two mechanisms and allows the supercooled contents of the tree’s cells to avoid crystallizing.

All three cellular mechanisms are intended to keep living cells from freezing. That’s the key for the tree; don’t allow living cells to freeze.

A tree doesn’t have to keep all of its cells from freezing, just the living ones which are primarily the phloem cells. This is significant, since much of a tree’s living trunk is made up of cells that are dead, such as xylem cells. These dead cells can and do freeze, but even the lowest temperature doesn’t have an adverse effect. While a majority of a tree’s above-ground cells do indeed freeze regularly when exposed to subfreezing temperatures, the living cells remain unfrozen and active on a reduced level. There are living cells in the trunk that remain unfrozen even though they are right next to – and at the same temperature as – dead cells that are frozen solid!

frostTree

Some trees like many birches can survive temperatures well below -100 F

This seemingly mystical combination of pliable membranes, natural antifreeze, and glasslike supercooling, with frost on the outside and viscous dehydration on the inside, helps trees avoid freezing injury to living cells. Trees are the largest, oldest living organism on our planet and don’t grow older and larger without having very specific strategies for survival.

However, sometimes, trees aren’t able to withstand extreme conditions, especially if nature provides an unusual change.  While trees have evolved amazing strategies for withstanding the winter cold, sometimes it gets so cold that trees can explode. During spells of extreme cold or especially when trees haven’t had time to acclimate before the cold arrives, the life-sustaining sap inside a tree can begin to freeze. Sap contains water so it expands when frozen, putting pressure on the bark, which can break and create an explosion, so to speak.

Proper winter care is critical to protect your trees with mulch and water to help trees make it through the winter months. For more information on winter tree care, check out this publication: Winterize Your Trees.

Resources
Purdue Landscape Report, Website
Winterize Your Trees, The Education Store, Purdue Extension resource center
Tree Defect Identification, The Education Store
Forest/Timber, Playlist, Purdue Extension – Forestry and Natural Resources YouTube channel
Urban Forestry, Purdue Extension – FNR playlist
Winter Weather Tree Tips, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Tree Wounds and Healing, Got Nature? Blog
Water Now to Minimize Winter Injury, Indiana Yard and Garden – Purdue Consumer Horticulture

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


Posted on March 3rd, 2021 in Forestry, How To, Plants, Woodlands | No Comments »

In this edition of ID That Tree, Purdue Extension forester Lenny Farlee introduces the mockernut or white hickory. This species is typically found on high dry ridges and other dry soil locations. Identifying characteristics include a very rounded and oftentimes hairy buds, hair on the leaf stems and twigs in early spring and summer, and a tightly networked ridged and silvery bark.

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
Hickory and Pecan Species, The Education Store, Purdue Extension resource center
Mockernut Hickory, Native Trees of Indiana River Walk, Purdue – Fort Wayne
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
Investing in Indiana Woodlands, The Education Store
Tree Appraisal and the Value of Trees, The Education Store
Forest Improvement Handbook, The Education Store

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


PurdueExt2020ImpactReportPurdue Extension: Purdue Extension is your educational partner for life. The 2020 Impact Report shows how Extension delivers practical, research-based information and events for Indiana’s residents in agriculture and natural resources, health and human sciences, and community development, and trains tomorrow’s leaders through Indiana 4-H Youth Development.

Check out the Purdue Extension-Forestry & Natural Resource highlights on the following programs and extension specialists:

  • Keeping our forests healthy, pg. 5. Program: Forest Management for the Private Woodland Owner taught by Ron Rathfon, Purdue Extension Forester at the Southern Indiana Purdue Agricultural Center. For the northern counties Lenny Farlee, sustaining hardwood extension specialist with Purdue Forestry and Natural Resources, teaches the Management for the Private Woodland Owner Course.
  • A comprehensive approach to community development, pg. 43. Program: Enhancing the Value of Public Spaces, Kara Salazar, program leader and extension specialist for sustainable communities, and Dan Walker, community planning extension specialist, both with Purdue Forestry and Natural Resources.
  • Actively managing natural resources, pg. 52. Programs in partnership with Illinois-Indiana Sea Grant (IISG): Tipping Point Planner, Conservation Through Community Leadership and Sustainable Communities, Kara Salazar, program leader and extension specialist for sustainable communities.

Resources
Woodland Stewardship for Landowners, Playlist, Purdue Extension – Forestry and Natural Resources YouTube channel
A Woodland Management Moment, FNR – Ext Playlist
Hardwood Ecosystem Experiment – Wildlife Responses to Timber Harvesting, The Education Store, Purdue Extension resource center
Forest Improvement Handbook, The Education Store
Community Planning, FNR -Ext Playlist
Enhancing the Value of Public Spaces: Creating Healthy Communities, The Education Store
Community Planning for Agriculture and Natural Resources: A Guide for Local Government, The Education Store
Tipping Point Planner, Website
Tipping Point Planner, The Education Store

Purdue Extension

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

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

Kara Salazar, Assistant Program Leader and Extension Specialist for Sustainable Communities
Purdue Department of Forestry and Natural Resources

Dan Walker, Community Planning Extension Specialist
Purdue Department of Forestry and Natural Resources


In this edition of ID That Tree, Purdue Extension forester Lenny Farlee introduces you to a native Indiana tree sometimes called the Indiana banana. Meet the pawpaw, a shade-tolerant, fruit-producing, simple-leaved species.

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
Pawpaw: The Midwest Banana?, Indiana Yard and Garden – Purdue Consumer Horticulture
Growing Pawpaws, The Education Store, Purdue Extension resource center
Unexpected Plants and Animals of Indiana: Pawpaw tree
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
Investing in Indiana Woodlands, The Education Store
Tree Appraisal and the Value of Trees, The Education Store
Forest Improvement Handbook, The Education Store

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


In this edition of ID That Tree, Purdue Extension forester Lenny Farlee introduces you to the chinkapin oak, a member of the white oak family that has leaves that appear sharp like red/black oaks, but really are not. Learn more inside as well as other easier to identify characteristics.

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
Chinkapin Oak, Native Trees of Indiana River Walk, Purdue Fort Wayne
Quercus muehlenbergii, The Purdue Arboretum Explorer
White Oak, The Education Store, Purdue Extension resource center
ID That Tree, Purdue Extension – Forestry & Natural Resources Playlist
A Woodland Management Moment, Purdue Extension – Forestry & Natural Resources Playlist
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store

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


In this edition of ID That Tree, Purdue Extension forester Lenny Farlee introduces you to a rebel of the oak family, the shingle oak. Unlike its relatives, the shingle oak’s shiny leaves do not feature any lobes and have a complete margin. Learn more about this oddity and other ways to identify this species inside.

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
Shingle Oak, Native Trees of Indiana River Walk, Purdue Fort Wayne
Quercus imbricaria, The Purdue Arboretum Explorer
ID That Tree, Purdue Extension – Forestry & Natural Resources Playlist
A Woodland Management Moment, Purdue Extension – Forestry & Natural Resources Playlist
Investing in Indiana Woodlands, The Education Store, Purdue Extension resource center
Forest Improvement Handbook, The Education Store

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


Posted on February 18th, 2021 in Forestry, Gardening, How To, Plants, Woodlands | No Comments »

In this edition of ID That Tree, Purdue Extension forester Lenny Farlee introduces you to the white oak group. In addition to identifying four common varieties of white oak by their leaves and acorns, he also explains how to differentiate them from their cousins, the red oaks.

 

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
White Oak, The Education Store, Purdue Extension – Forestry and Natural Resources
FNR Hardwood – White Oak, The Purdue Arboretum Explorer
White Oak, Native Trees of Indiana River Walk, Purdue – Fort Wayne
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
Investing in Indiana Woodlands, The Education Store
Tree Appraisal and the Value of Trees, The Education Store
Forest Improvement Handbook, The Education Store

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


In this edition of ID That Tree, Purdue Extension forester Lenny Farlee introduces a whole family of trees, the red oak group. He identifies four common species and shows how to differentiate between them as well as how to keep the red and white oak groups separated.

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
Red Oak, The Education Store, Purdue Extension – Forestry and Natural Resources
FNR Hardwood – Red Oak, The Purdue Arboretum Explorer
Red Oak, Native Trees of Indiana River Walk, Purdue – Fort Wayne
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
Investing in Indiana Woodlands, The Education Store
Tree Appraisal and the Value of Trees, The Education Store
Forest Improvement Handbook, The Education Store

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


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