Is My Black Walnut Dead: How To Tell If A Black Walnut Is Dead

Is My Black Walnut Dead: How To Tell If A Black Walnut Is Dead

By: Teo Spengler

Black walnuts are tough trees that can rise to over 100 feet (31 m.) and live hundreds of years. Every tree dies at some point though, even if only from old age. Black walnuts are also subject to some diseases and pests that can kill them at any age. “Is my black walnut dead,” you ask? If you want to know how to tell if a black walnut is dead or dying, read on. We’ll give you information on identifying a dead black walnut tree.

Is My Black Walnut Dead?

If you ask yourself whether your beautiful tree is now a dead black walnut, there must be something wrong with the tree. While it may be difficult to determine exactly what is wrong, it shouldn’t be too difficult to tell if the tree is actually dead or not.

How to tell if a black walnut is dead? The easiest way to determine this is to wait until spring and see what happens. Look carefully for signs of new growth like leaves and new shoots. If you see new growth, the tree is still alive. If not, it may be dead.

Identifying a Dead Black Walnut

If you just can’t wait until spring to determine whether your tree is still living, here are a few tests you can try. Flex the slender branchlets of the tree. If they bend easily, they are most likely alive, which indicates that the tree is not dead.

Another way to check whether your tree is dead is to scrape back the outer bark on young branches. If the tree’s bark is peeling, lift it and look at the cambium layer beneath. If it is green, the tree is alive.

Dying Black Walnut and Fungal Disease

Black walnuts are drought and pest resistant, but they can be damaged by a number of different agents. Many dying black walnut trees have been attacked by the thousand cankers disease. It results from a combination of boring insects called walnut twig beetles and a fungus.

The beetle bugs tunnel into branches and trunks of the walnut trees, carrying spores of the canker producing fungus, Geosmithia morbidato. The fungus infects the tree causing cankers that can girdle branches and trunks. Trees die in two to five years.

To figure out if your tree has this disease, look carefully at the tree. Do you see insect bore holes? Look for cankers on the tree bark. An early sign of thousand cankers disease is part of the canopy’s failure to leaf out.

Other Signs of Dying Black Walnut

Inspect the tree for peeling bark. Although walnut bark is normally quite shaggy, you should not be able to pull the bark away very easily. If you can, you are looking at a dying tree.

When you go to pull back the bark, you may find it already peeled back, exposing the cambium layer. If it is pulled back all the way around the tree trunk it is girdled, and your walnut tree is dead. A tree cannot live unless the cambium layer can transport water and nutrients from its root system to the canopy.

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How to Identify the Common Black Walnut Tree

Steve Nix is a member of the Society of American Foresters and a former forest resources analyst for the state of Alabama.

Black walnut trees (Juglan nigra) are found throughout much of the central-eastern part of the U.S., except in the far northern and far southern part of this range, but familiar elsewhere from the East Coast into the central plains.

They are part of the general plant family Juglandaceae, which includes all the walnuts as well as hickory trees. The Latin name, Juglans, derives from Jovis glans, "Jupiter's acorn"--figuratively, a nut fit for a god. There are 21 species in the genus that range across the north temperate Old World from southeast Europe east to Japan, and more widely in the New World from southeast Canada west to California and south to Argentina.

There are five native walnut species in North America: black walnut, butternut, Arizona walnut and two species in California. The two most commonly found walnuts found in native locations are the black walnut and butternut.

In its natural setting, the black walnut favors riparian zones--the transition areas between rivers, creeks and denser woods. It does best in sunny areas, as it is classified as shade intolerant.

The black walnut is known as an allelopathic tree: it releases chemicals in the ground that may poison other plants. A black walnut can sometimes be identified by the dead or yellowing plants in its vicinity.

It often appears as a kind of "weed" tree along roadsides and in open areas, due to the fact that squirrels and other animals harvest and spread the nuts. It is often found in the same environment as silver maples, basswoods, white ash, yellow-poplar, elm and hackberry trees.


How to Harvest Black Walnuts

Last Updated: November 5, 2020 References Approved

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Black walnuts are wild walnuts that are native to North America. In contrast to the English walnuts that you find in most grocery stores, black walnuts have a stronger flavor and are more difficult to break out of their shells. [1] X Research source In order to harvest these flavorful nuts correctly, you’ll need to wait until early fall and gather them when they are ripe. Once you’ve collected the nuts, remove the tough hulls and dry the nuts in their shells before cracking them open to get the nutmeat.


Comments (12)

Virginia White

Hi Jennifer,
I found a good site with the info you're looking for - it's not good. It says that the toxicity can last for years as the dead roots are still releasing juglone. I'm adding another address that had some rather startling info on the root/toxicity zone. It was a lot larger than I thought. That would be in the Ohio link here:
http://ohioline.osu.edu/hyg-fact/1000/1148.html

Hope this helps and wish the news was a bit better,
Ginger

Here is a link that might be useful: Black Walnut Toxicity

Artdeco

If your husband is willing to cut it down for you - do it!
And then plant 1 or 2 squirrel friendly trees in its place - such as Oak or Horsechestnut.

Our yard is surrounded by huge BW trees, so I understand your frustration. Even more frustrating is seeing little trees planted by squirrels, sprouting just beyond our fence in our neighbors yard, and they aren't removing them. Soon our yard will be a complete network of BW roots.
If you remove all your BW trees, you are reducing the odds of more trees appearing in the future at the other end of your lot which is currently juglone free.

I too have read that the juglone can persist for many yrs after a tree is removed, but if you plant only tolerant plants now, eventually you can work in others. Time flies so fast - before you know it 5 yrs will have passed!

If you leave the remaining tree, the roots will eventually travel much further than 25 ft. - this spring I found many pencil-sized roots just 6" below the surface from a neighbors tree >60' away. Cornell Univ found roots can grow 3 times the spread of the canopy.

I had planted yews in an area I thought was safe - they did great for years til 2 started dying, & I found walnuts buried inches from their trunks. So last fall I dug-out a whole row of 3' yews.

Black Walnuts are beautiful trees & serve an important role in nature, but they don't belong in a garden or small yard - they belong in large open areas. There are so many more suitable trees available - why leave a tree to grow that you will resent for all the years you live at this house?

And I haven't found any annuals that flourish under a BW.


The weight alone of walnuts typically does not cause limbs to crack and fall. There may be an underlying pest or disease problem. If you can re-submit your question with pictures of your tree and a recently fallen limb, it could provide more information available for a diagnosis. How old is the tree? Do you see any yellowing or dying leaves? There is a disease of walnut trees called Thousand Cankers Disease caused by the Walnut Twig Beetle recently spotted in Ohio.

Bottom line, consider re-submitting your question with pictures or more information about any additional symptoms you see affecting the leaves or bark, etc.

I have lived at this address over 35 years and the black walnut tree was already mature and tall. There are no yellow or dying leaves.The bark is all in tack. I do have 4 raccoons in my backyard where the tree is. a mother and her 3 youngsters. Would they try to get to the black walnuts for food? I took several pics and saved them on my computer, but haven't figured out how to attach them to this email.

Given no obvious leaf problems, yellowing, browning or loss or bark problems, it is possible the harsh winter affected some of the weaker limbs. Following is a link to the USDA Forest Service fact sheet on Black Walnut (Juglans nigra): http://www.na.fs.fed.us/spfo/pubs/silvics_manual/volume_2/juglans/nigra.htm

The section on Damaging Agents states: "Decay, dieback, and frost also cause damage. At times dieback and frost damage may be extensive. Late spring frosts kill succulent new growth and thus reduce height growth and destroy desirable form. Late winter warming periods sometimes cause walnut trees to break dormancy prematurely, resulting in freezing injury to the stem tissue."

If you are still concerned about the health of your tree, consult a certified arborist in your area. Following is a link to an OSU Extension fact sheet about hiring arborists: http://ohioline.osu.edu/hyg-fact/1000/1032.html

An yes, raccoons and squirrels will eat walnuts.

Pat, thank you for answering my question about the black walnut tree!


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