Are Trees in Species-Rich Urban Plantings Less Susceptible to Pest Damage?

Two-part image: Left side shows tree branches over a suburban sidewalk, and on which many small bumps can be seen. Right side shows a close-up on a tree trunk with the same small bumps covering nearly all of the bark.
Gloomy scales (Melanaspis tenebricosa) can be highly abundant on red maples in cities. At left is an infested branch from a young red maple, while the close-up at right shows how densely clustered gloomy scales can be on red maple trunks. (Photos by Caleb J. Wilson, Ph.D.)

By Caleb J. Wilson, Ph.D.

Trees in species-rich forests often suffer less damage from insect pests compared to trees in forests dominated by a few common species. Many hypotheses have been proposed to explain these findings. Two that have gained prominence among scientists are “the resource concentration hypothesis” and “the enemies hypothesis,” both coined by Richard B. Root, Ph.D., in a landmark publication in Ecological Monographs in 1973.

Read the article here>>>

Cold wave and lack of snow cover will not be good for our landscapes.

Temperatures with the coming cold wave will be comparable to the December 2022 cold wave. Here is a comparison:

December 2022 cold snap highs and lows:

45/20, 23/-9, 12/1, 19/7, 26/13, 32/24, 51/27, 59/40

January 2024 cold snap starting Saturday, highs and lows:

31/10, 18/10, 19/9, 17/5, 24/18, 28/14, 22/10, 22/11

The current forecast for the 2024 cold snap presumes little or no snow on the ground. In the 2022 cold snap, we had 3-6 inches of snow on the ground which reduced temperatures significantly and also afforded an insulating blanket to plant root systems.

A blizzard with several inches of snow ushered in the 2022 cold snap in Cincinnati which helped protects plant root systems. This time around, it looks like snow may be scarce.

Lack of snow cover means slightly warmer air temperatures but there will be nothing to protect plant root systems from the bitter cold. Plants like knockout roses, cherry laurel, Japanese plum yew, Blue Atlas cedar, and others which are cold sensitive may be at risk. Other plants may also be at risk since we were in drought for months as recently as last week.

What can you do?

Be sure plant root systems are well mulched.

Be sure soil is moist. This should not be a problem for most plants with recent rains.

For sensitive shrubs such as knockout or other roses, you can build a wire cage around the plant and fill it with leaves or mulch, covering most of the plant. Just be sure to remove all this before growth starts in the spring.

This cold snap will be more prolonged than in 2022.

Stay warm!

Christmas Day 2022

OSU Extension Collaborates with the North American Pawpaw Growers Association at Mansfield Correctional Institution

Extension educators pose with newly planted pawpaw grove

On a bright, sunny Thursday morning in October, ANR Extension Educators, Carrie Brown of Fairfield County and Dan Lima of Belmont County, teamed up with the North American Pawpaw Growers Association (NAPGA) and the Ohio Nut Growers Association (ONGA) to establish a grove of pawpaw trees at the Mansfield Correctional Institution.

Arbor Doctor December 2023 client update and latest blog postings

Welcome to meteorological winter and the holiday season! I can’t believe the year is almost over. We are still very busy at Arbor Doctor.

2024, Arbor Doctor’s 20th year in business

As quickly as the holiday season has come along, the realization just hit me that 2024 will be Arbor Doctor’s 20th year in business. How is that even possible? Some of you have been with us since the beginning. Whether you are loyal fans or new to our family, I thank you from the bottom of my heart.

The Landscape Below Ground

State Street Miyabei maple (Acer miyabei ‘Morton’) planted in 1932 at the Morton Arboretum.

In October I had the amazing opportunity to attend the Landscape Below Ground Symposium at the Morton Arboretum in Lisle, IL. This was the 30th anniversary for this symposium which is held every five years and brings together the top researchers from around the world to present the latest research on the below ground portions of trees. For a tree geek like me it was an amazing experience and I learned a lot. Researchers presented from nine countries around the world from New Zealand to Shanghai and from Italy to the Netherlands. The Morton Arboretum itself is an amazing facility with a charge from its founding to further the cause of tree research. They call themselves The Champion of Trees.

Dr. Gary Watson, emeritus researcher at the Morton Arboretum and and one of the founders of the symposium, presenting on day 1.

Prepay letters coming soon

Very soon we will be sending out our prepay letters for 2024. These letters detail the services which you are scheduled for during the coming year. The letter also offers the opportunity to prepay for the year with a discount. This is simply an option and not an obligation.

It is important to note that our ongoing plant health care services do not automatically stop at the end of a calendar year. If there are any changes you would like to make to your program, or if you would like us to come out and discuss what we are doing and what our plans are for the future, please contact us. Winter is a great time for us to catch up and go over things.

This winter we will once again be doing site visits to a number of our plant health care clients’ properties. These are complimentary visits where we will inventory landscape plants, update our notes, and inspect for any issues which might be going on. We also use this as a training opportunity for our team during the winter.

Training is very important to us and we are always looking for opportunities to increase our knowledge and skills. These site visits give us the opportunity to interact in the field and hone our diagnostic skills.

It’s Dry Out There.

It’s more difficult to notice this time of the year with cooler temperatures and most plants in or near dormancy but conditions remain quite dry in the Cincinnati area. We are now nearly 5 inches below normal in rainfall for the year and most of that deficit has been in the fall.

If you have been watering up until Thanksgiving, as we recommend, you likely have adequate moisture in your soil. If not, it is likely that your soils are still quite dry below the surface and watering remains necessary. This is the second straight year with drought and many of our trees, especially evergreens, are showing it.

I would expect more problems with evergreens in the future due to the two years of drought. It is my belief that the drought of last fall accentuated the effects of the cold snap that we had around Christmas and evergreens that were adequately watered appear to have been less impacted by the cold.

A warm and dry December but winter is not cancelled>>>

December 9, 2023 Soil Moisture, Drought, and Condition Monitoring Report. Moderately Dry Conditions at Cheviot OH 3W. Widespread Dry and Drought Conditions in the South and Southeast, the mid-Atlantic, the Mississippi valley, and the lower Missouri valley with moderate drought in much of eastern Kentucky and southern Indiana. Severe drought in southeast Kentucky>>>

Please remember to water…correctly!

Water once per week, one inch per week, under the entire branch spread, in the absence of rain, May through November. Either rainfall or your watering should equal the one inch per week. Do not water if the soil is already moist. Put out a sprinkler and a straight sided soup can or rain gauge and measure one inch per week. Measure the rainfall which falls in your yard. Your trees don’t care what fell at the airport!

For new trees and shrubs, be sure to saturate the root ball once or twice a week. Container grown material is especially susceptible to drying out in the first couple years after planting.

If burlap was left on new trees, it will repel water and the tree or shrub may die. Be sure burlap and twine are removed from the top of all root balls. If your landscaper disagrees, refer him or her to the American National Standards Institute (ANSI) industry standard for installation of landscape plants.

To the extent possible recycle fallen leaves back into the soil around the trees and maintain mulch around the trees to a radius of at least 3-5 feet. Keep mulch off trunks. Use a coarse textured mulch. Avoid triple shredded mulch. Aged arborist wood chips ( https://getchipdrop.com/ ), mulched and composted leaves, pine bark, and pine straw are all good. Very finely ground mulches such as triple ground hardwood mulch are not beneficial and may inhibit moisture and oxygen exchange.

Drought: How Dry Seasons Affect Woody Plants>>>

1-inch capacity rain gauge  >>>

Taylor rain gauge   >>>

Watering: How and when>>>

Watering Trees and Shrubs>>>

Metal Rectangular Spot Sprinkler

8-Pattern Sprinkler

What’s Happening Now. Timing of Tree Planting and Landscape Installations

We are currently finishing our early winter treatments as well as plantings, air knife, pruning and others. Our late winter treatments will commence in the latter part of January, or as conditions permit.

For any questions or inquiries you may submit a request in our customer portal or contact Director of Operations Camille Rechel at 513-661-2673 or camille@arbordoctor.com.

Our team updates

Malessa Johnson joined our team this fall and has been a great addition. She has experience working in garden centers and interior plantscaping.

We spend a great deal of time and resources on training and field visits. We have a great core horticultural team this year of (left to right) Plant Health Care Specialist Ali Randall, Plant Health Care Specialist Noah Riggs, Office Manager Diane Smith, Principal Owner Ron Rothhaas, Director of Operations Camille Rechel, and Plant Health Care Team Lead Steve Middleton.

Updates posted on our blog pages over the past couple months:

OSU Extension Collaborates with the North American Pawpaw Growers Association at Mansfield Correctional Institution

When you think of Tree Trimming, Think Safety First, Cost Second!

SLF Update – Ohio’s Spotted Lanternfly Quarantine Expanded and More

USDA Updates the Plant Hardiness Zone Map Updated in 2023

Living With Wildlife: Raptors, Snakes & Canids – Oh My!

Fall Lawn Care – Putting your lawn to bed for Winter.

I bought a “Live” Christmas tree. What’s the best way to take care of it?”

How Central Park Was Created Entirely By Design and Not By Nature

Box Tree (Boxwood) Moth: New Detection, What to Look For, and Management

Beech Blight Aphids Got Talent

Out on a Limb. Arboriculture as a career.

https://www.youtube.com/embed/flljst28Wcs?feature=oembed How Central Park Was Created Entirely By Design and Not By Nature

Box Tree (Boxwood) Moth: New Detection, What to Look For, and Management

Beech Blight Aphids Got Talent

Look Closely at Flowers for a Tiny Threat to Pollinators

Out on a Limb. Arboriculture as a career.  

Dodder’s Tangled Tale

From Basin to Banks: Wetland Restoration

Spotted Lanternfly. THEY DON’T BITE!

Some additional thoughts from Ron

“I Heard The Bells On Christmas Day”

I heard the bells on Christmas day
Their old familiar carols play
And mild and sweet their songs repeat
Of peace on earth good will to men

And the bells are ringing (Peace on Earth)
Like a choir they’re singing (Peace on Earth)
In my heart I hear them
Peace on earth, good will to men

And in despair I bowed my head
There is no peace on earth I said
For hate is strong and mocks the song
Of peace on earth, good will to men

But the bells are ringing (Peace on Earth)
Like a choir singing (Peace on Earth)
Does anybody hear them?
Peace on earth, good will to men

Then rang the bells more loud and deep
God is not dead, nor doth He sleep (Peace on Earth, peace on Earth)
The wrong shall fail, the right prevail
With peace on earth, good will to men


Then ringing singing on its way
The world revolved from night to day
A voice, a chime, a chant sublime
Of peace on earth, good will to men

And the bells they’re ringing (Peace on Earth)
Like a choir they’re singing (Peace on Earth)
And with our hearts we’ll hear them
Peace on earth, good will to men

Do you hear the bells they’re ringing? (Peace on Earth)
The life the angels singing (Peace on Earth)
Open up your heart and hear them (Peace on Earth)
Peace on earth, good will to men
Peace on earth, Peace on earth
Peace on earth, Good will to men

This is one of my favorite songs at this time of the year. I feel like I may have shared it once before but at this time, in this world, with war raging in the Ukraine and in the Middle East, it seems more appropriate than ever.

And in despair I bowed my head
There is no peace on earth I said
For hate is strong and mocks the song
Of peace on earth, good will to men

My heart breaks for the many people affected by war in the Ukraine, the middle east, and particularly Israel.

This must be a painful and heartbreaking Hanukkah season. To my Jewish friends, rest assured that my prayers go out to you and yours at this very painful time.

Then rang the bells more loud and deep
God is not dead, nor doth He sleep (Peace on Earth, peace on Earth)
The wrong shall fail, the right prevail
With peace on earth, good will to men

As it is written in Isaiah 9:

The people walking in darkness
    have seen a great light;
on those living in the land of deep darkness
    a light has dawned.
You have enlarged the nation
    and increased their joy;
they rejoice before you
    as people rejoice at the harvest,
as warriors rejoice
    when dividing the plunder.
For as in the day of Midian’s defeat,
    you have shattered
the yoke that burdens them,
    the bar across their shoulders,
    the rod of their oppressor.
Every warrior’s boot used in battle
    and every garment rolled in blood
will be destined for burning,
    will be fuel for the fire.
For to us a child is born,
    to us a son is given,
    and the government will be on his shoulders.
And he will be called
    Wonderful Counselor, Mighty God,
    Everlasting Father, Prince of Peace.
Of the greatness of his government and peace
    there will be no end.

Have a blessed Christmas everyone and to my Jewish friends, a blessed Hanukkah.

Have a blessed new year. If you have any questions or inquiries you may submit a request in our customer portal or contact Director of Operations Camille Rechel at 513-661-2673 or camille@arbordoctor.com.

Beech Blight Aphids Got Talent

Beech Blight Aphid

The talented and uniquely entertaining Beech Blight Aphids (Grylloprociphilus imbricator) are taking the stage in Ohio. Some of the best line dancing can be seen in Johnson Woods State Nature Preserve in Wayne County, OH. Jim Chatfield (OSU Extension Emeritus) and I observed chorus lines of beech blight aphids shaking their derrieres on their namesake host in the Preserve last week.