Food forest, question about black walnuts

Greetings! I've been lurking for awhile, love the site. Recently purchased 10 acres in Missouri. 300 ft wide 1320 ft long. The long side faces the south. Back 3 acres are probly 20 year regrowth forest. At the front I have a good slope toward a part time creek thats perfect for a food forest, but there are several 5ish year old black walnut trees all 6" or less. I know they are alleopathic(sp?). What is the best way to remove them and also remove their toxins? If you cut one down do the roots still secrete toxins? Stumps would not be an issue if they posed no hazard to other trees. I have lots of mullberrys on the place and suppose I could surround each tree if needed. Any ideas? Thanks!

Hi Eric,

My understanding is that the juglone from a well established will remain present in the surrounding soil long after the tree has been cut, due to the roots and fallen leaves continuing to secrete it as it decays. I think it can take years if I'm not mistaken, though I'm not sure about younger trees, as you seem to be describing. You said the trees are 5 years old but only 6 inches...Did you mean feet?

If it were me I'd probably go with the flow and plant stuff that doesn't mind juglone around the walnut trees as a buffer, and then plant whatever else beyond that. There are many lists that can be found via search engines both on this site and elsewhere.

Travis Philp wrote:Hi Eric,

My understanding is that the juglone from a well established will remain present in the surrounding soil long after the tree has been cut, due to the roots and fallen leaves continuing to secrete it as it decays. I think it can take years if I'm not mistaken, though I'm not sure about younger trees, as you seem to be describing. You said the trees are 5 years old but only 6 inches...Did you mean feet?

If it were me I'd probably go with the flow and plant stuff that doesn't mind juglone around the walnut trees as a buffer, and then plant whatever else beyond that. There are many lists that can be found via search engines both on this site and elsewhere.

I can see how that was confusing for you. I was thinking diameter. sorry

Black walnuts are one of the best food crops you could have, alternately you could maintain them as a coppice (honestly they regrow so well it would be hard to kill them without removing the stump). The regrowth is usually very straight, the wood is somewhat rot resistant and grows fairly fast in good conditions.

Some food plants that thrive near walnut are mulberry, pawpaw, elderberry, hazelnut. I would recommend working with what you've got.

peace

I'm with Osker, work with what you've got and try to keep them, but there is a way to speed up the decomposition if you do decide to cut them down.

Once you have cut the tree and ground down the stump/root, there will still be stray roots that new growth can coppice from. One way to kill that would be to keep it so wet that it will die of rot: hammer in some of that plastic garden edging around it and keep it flooded for a couple of weeks. Have you seen trees killed by flood waters? Try and recreate that on a small scale around the tree.

So now you have a dead zone from your artificially engineered "flood". You still have juglone in the soil, and you will need soil fungi to decompose it. Take out the plastic garden edging and let it dry out. Cover the area with 6" of chipped mulch and throw any mushrooms you can find on it. Water it every day to create good conditions for the fungi to grow. After a few months, the fungi should have taken care of the juglone.

And for more on fungi, see my topic on mycoremediation

Another way to kill trees after they've been cut is to drill holes down into the face of the wound and pour vinegar down those suckers. You'd have to do a search for the details on that method but I've heard it used to good effect against severely invasive trees like European Buckthorn.

The problem I see with flooding the ground is you'd be washing away a lot of the nutrients too.

If it were my land, I would look at how to fit the walnuts into my food forest, rather than planning to take them out. They provide benefits that make them worth having - and are already well started and (apparently from your post) healthy. Work with them, get the benefit of their edible - and marketable - nuts, let them grow to where they're worth harvesting for their lumber. In the meantime, plant around them with choices that are not harmed by juglone.

I would think that wherever we want to start up a food forest, one of our first priorities should be to survey what has already got itself established that we can make use of and work with. Those plants tell us about what is likely to succeed in the space and give us a head start on our plan - if we incorporate them into it.

I have 6 or 7 Black Walnut trees on the 6-acre piece of land in Southern Appalachia I purchased 7 years ago. I'm guessing the trees are 30-50 years old but they do not produce many walnuts. We had a bumper crop of walnuts four years back but nothing to speak of since. I recently discovered permaculture and the permies.com site so I am essentially a freshman apprentice. I like the idea of guilds and look forward to adding apple, mulberry and comfrey to the walnut "grove".

Two members of the black walnut grove live on the edge of a growing gully with a seasonal creek. I wonder if the gully is impairing the root system of the trees and therefore their production.

Any ideas for or pointers to good black walnut tree cultivation? As you can see from the attached photos the grove is on a rather steep slope with Black Locust trees nearby. The hillside is surrounded by "wild" forest.

Thanks for your input and guidance.

Two members of the black walnut grove live on the edge of a growing gully with a seasonal creek. I wonder if the gully is impairing the root system of the trees and therefore their production.

Don't worry about the root system. Black walnuts grow like weeds in the Missouri Ozarks, a place with thin soil and bedrock that is "harder than the back of God's head" to quote a local. What is more likely your problem is that they need more nutrients to produce a good nut crop. Black walnuts will "mast", that is produce a big crop in a favorable year and then have a reduced crop in succeeding years that are less favorable. You can help this along by fertilizing the tree, giving it enough nutrients to put out a better crop every year. Rather than use a commercial (chemical) fertilizer that would just give a flush of green, you want to increase the total nutrients in the soil under the tree. You could do this by heavy mulching with poultry litter or compost or wood chippings under the trees in question.

Seeding some crimson clover around the trees in the fall as a cover crop to increase soil nitrogen might also be a good idea. Clover will also help with the problem of retaining mulch and soil on the steep slope. Plus it is a good bee plant when it flowers in the late winter.

Thanks, John! I read that nitrogen was required for bountiful walnuts... And I have plenty of downed trees from a hillside I've been cleaning up since the property purchase - a lightning strike and forest fire in the late 1990's led to the deaths of dozens of pines and other species of trees.

I'll work on preparing that mulch of wood chips and poultry litter for immediate treatment and see about sowing the crimson clover in the fall.

Thanks again for your recommendation!

These mountains tend to be phosphorus deficient, so it may be worth buying some rock phosphate, digging a deep hole within the dripline of the trees, and dumping a bunch in. There's no need to spread it, the trees will find it and use what they need, the important thing is to get it deep, as phosphorus doesn't move well in soils.

Another thing to try would be to coppice one or more of them and graft select walnut varieties onto the regrowth. Many select cultivars are chosen for consistent bearing, as well as kernel size. I'm told that select hickories and even pecans are graft compatible with black walnut, I haven't tried that myself, but I intend to soon.

peace

Eric, I am about to experiment by cutting the locust saplings near the walnuts, and planting things around the wonderful locust stumps. I have found that anything grows great around old locust stumps, which are LEGUMES, like giant BEANS!!! When I left my land for five years, walnut saplings took over. I was able to kill one by ringing the stump. The other that I cut sprout over and over. Indians used to make butternut clearings by ringing all trees and burning the stumps.
I made one butternut clearing with 12 butternuts.
After 5 years neglect, raspberries covered the ground under one giant walnut. I did not have the heart to cut it. I put manure on the raspberries and pruned them and mulched them last winter. I am presently eating large berries, all I can stand.
If your mulberries are red, they may be rare. One book about tree death says red ones are dying. Walnuts are supposed to be dying out too.



.

Greta Fields wrote:Eric, I am about to experiment by cutting the locust saplings near the walnuts, and planting things around the wonderful locust stumps. I have found that anything grows great around old locust stumps, which are LEGUMES, like giant BEANS!!! When I left my land for five years, walnut saplings took over. I was able to kill one by ringing the stump. The other that I cut sprout over and over. Indians used to make butternut clearings by ringing all trees and burning the stumps.
I made one butternut clearing with 12 butternuts.
After 5 years neglect, raspberries covered the ground under one giant walnut. I did not have the heart to cut it. I put manure on the raspberries and pruned them and mulched them last winter. I am presently eating large berries, all I can stand.
If your mulberries are red, they may be rare. One book about tree death says red ones are dying. Walnuts are supposed to be dying out too.



.

I guess I'll start doing my research and see what plants thrive around them and plant accordingly. If they ever become a problem I can remove them in the future.....I just don't like the taste of black walnuts lol. They are not dying around here, these things grow like a weed in Missouri. All of my mullberries turn black when ripe, and I have a bunch. Funny you mention black locust, I just discovered today I have three at the top of the hill where I want to start the food forest, they are full of leathery pods, surprising how many they can make

Yeah, that's what I am doing too. I once found a list of 200 plants which will grow under walnuts, but I can't find it now.
I really value the locust trees now. However, they come up everywhere too and stumps which are cut start runners/
If you solve the problems, let me kow how you do it! I will probably wind up burning walnut stumps in areas I want cleared.

If you cut locusts higher off the ground they won't root sucker.

There is a disease affecting black walnuts called thousand canker disease, it's native to the walnuts in the southwest but began moving east recently.

http://www.thousandcankers.com/tcd-information.php

I think that is right. I ringed one walnut tree and it never suckered either.

if the bl walnuts are that small they should remove just fine..there is a list I can give you of what will grow with juglone..


Ohio State University Extension Fact Sheet
Horticulture and Crop Science
2021 Coffey Rd., Columbus, Ohio 43210-1086

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Black Walnut Toxicity to Plants, Humans and Horses
HYG-1148-93
Richard C. Funt
Jane Martin

The roots of Black Walnut (Juglans nigra L.) and Butternut (Juglans cinerea L.) produce a substance known as juglone (5-hydroxy-alphanapthaquinone). Persian (English or Carpathian) walnut trees are sometimes grafted onto black walnut rootstocks. Many plants such as tomato, potato, blackberry, blueberry, azalea, mountain laurel, rhododendron, red pine and apple may be injured or killed within one to two months of growth within the root zone of these trees. The toxic zone from a mature tree occurs on average in a 50 to 60 foot radius from the trunk, but can be up to 80 feet. The area affected extends outward each year as a tree enlarges. Young trees two to eight feet high can have a root diameter twice the height of the top of the tree, with susceptible plants dead within the root zone and dying at the margins.

Not all plants are sensitive to juglone. Many trees, vines, shrubs, groundcovers, annuals and perennials will grow in close proximity to a walnut tree. Certain cultivars of "resistant" species are reported to do poorly. Black walnut has been recommended for pastures on hillsides in the Ohio Valley and Appalachian mountain regions. Trees hold the soil, prevent erosion and provide shade for cattle. The beneficial effect of black walnut on pastures in encouraging the growth of Kentucky bluegrass (Poa pratensis L.) and other grasses appears to be valid as long as there is sufficient sunlight and water.

Gardeners should carefully consider the planting site for black walnut, butternut, or persian walnut seedlings grafted to black walnut rootstock, if other garden or landscape plants are to be grown within the root zone of mature trees. Persian walnut seedlings or trees grafted onto Persian walnut rootstocks do not appear to have a toxic effect on other plants.

Horses may be affected by black walnut chips or sawdust when they are used for bedding material. Close association with walnut trees while pollen is being shed (typically in May) also produce allergic symptoms in both horses and humans. The juglone toxin occurs in the leaves, bark and wood of walnut, but these contain lower concentrations than in the roots. Juglone is poorly soluble in water and does not move very far in the soil.

Walnut leaves can be composted because the toxin breaks down when exposed to air, water and bacteria. The toxic effect can be degraded in two to four weeks. In soil, breakdown may take up to two months. Black walnut leaves may be composted separately, and the finished compost tested for toxicity by planting tomato seedlings in it. Sawdust mulch, fresh sawdust or chips from street tree prunings from black walnut are not suggested for plants sensitive to juglone, such as blueberry or other plants that are sensitive to juglone. However, composting of bark for a minimum of six months provides a safe mulch even for plants sensitive to juglone.

Plants Observed Growing Under or Near Black Walnut*
Trees
Japanese Maples, Acer palmatum and its cultivars
Southern Catalpa, Catalpa bignonioides
Eastern Redbud, Cercis canadensis
Canadian Hemlock, Tsuga canadensis
Vines and Shrubs
Clematis 'Red Cardinal'
February Daphne, Daphne mezereum
Euonymus species
Weeping Forsythia, Forsythia suspensa
Rose of Sharon, Hibiscus syriacus
Tartarian Honeysuckle, Lonicera tatarica, and most other Lonicera species
Virginia Creeper, Parthenocissus quinquefolia
** Pinxterbloom, Rhododendron periclymenoides
**'Gibraltar' and 'Balzac', Rhododendron Exbury hybrids
Multiflora Rose, Rosa multiflora
Black Raspberry, Rubus occidentalis
Arborvitaes, Thuja species
** Koreanspice Viburnum, Viburnum carlesii, and most other Viburnum species
Annuals
Pot-marigold, Calendula officinalis 'Nonstop'
Begonia, fibrous cultivars
Morning Glory, Ipomoea 'Heavenly Blue'
Pansy Viola
Zinnia species
Vegetables
Squashes, Melons, Beans, Carrots, Corn
Fruit Trees
Peach, Nectarine, Cherry, Plum
Prunus species Pear-Pyrus species
Herbaceous Perennials
Bugleweed, Ajuga reptans
Hollyhock, Alcea rosea
American Wood Anemone, Anemone quinquefolia
Jack-in-the-Pulpit, Arisaema triphyllum
European Wild Ginger, Asarum europaeum
Astilbe species
Bellflower, Campanula latifolia
**Chrysanthemum species (some)
Glory-of-the-Snow, Chionodoxa luciliae
Spring Beauty, Claytonia virginica
Crocus species
Dutchman's Breeches, Dicentra cucullaria
Leopard's-Bane, Doronicum species
Crested Wood Fern, Dryopteris cristata
Spanish Bluebell, Endymion hispanicus
Winter Aconite, Eranthis hyemalis
Snowdrop, Galanthus nivalis
Sweet Woodruff, Galium odoratum
Herb Robert, Geranium robertianum
Cranesbill, Geranium sanguineum
Grasses (most) Gramineae family
Jerusalem Artichoke, Helianthus tuberosus
Common Daylily, Hemerocallis 'Pluie de Feu'
Coral Bells, Heuchera x brizoides
Orange Hawkweed, Hieracium aurantiacum
Plantain-lily, Hosta fortunei 'Glauca'
Hosta lancifolia
Hosta marginata
Hosta undulata 'Variegata'
Common Hyacinth, Hyacinthus Orientalis 'City of Haarlem'
Virginia Waterleaf, Hydrophyllum virginianum
Siberian Iris, Iris sibirica
Balm, Monarda didyma
Wild Bergamot, M. fistulosa
Grape Hyacinth, Muscari botryoides
Sweet Cicely, Myrrhis odorata 'Yellow Cheerfulness,' 'Geranium,' 'Tete a Tete,' 'Sundial,' and 'February Gold'
Sundrops, Oenothera fruticosa
Senstitive Fern, Onoclea sensibilis
Cinnamon Fern, Osmunda cinnamomea
Peony, **Paeonia species (some)
Summer Phlox, Phlox paniculata
Mayapple, Podophyllum peltatum
Jacob's-Ladder, Polemonium reptans
Great Solomon's-Seal, Polygonatum commutatum
Polyanthus Primrose, Primula x polyantha
Lungwort, Pulmonaria species
Bloodroot, Sanguinaria canadensis
Siberian Squill, Scilla sibirica
Goldmoss Stonecrop, Sedum acre
Showy Sedum, Sedum spectabile
Lamb's-Ear, Stachys byzantina
Spiderwort, Tradescantia virginiana
Nodding Trillium, Trillium cernuum
White Wake-Robin, Trillium grandiflorum
Tulipa Darwin 'White Valcano' and 'Cum Laude,' Parrot 'Blue Parrot,' Greigii 'Toronto'
Big Merrybells, Uvularia grandiflora
Canada Violet, Viola canadensis
Horned Violet, Viola cornuta
Woolly Blue Violet, Viola sororia
*These are based upon observations and not from clinical tests.
**Cultivars of some species may do poorly.

Plants That Do Not Grow Within 50 Feet of Drip Line of Black Walnut
Herbaceous Perennials
Colorado Columbine, Aquilegia caerulea
Wild Columbine, Aquilegia canadensis
Asparagus, Asparagus offinalis
*Chrysanthemum Chrysanthumum species (some)
Baptisia australis
Hydrangea species
Lilies, Lilium species (particularly the Asian hybrids)
Alfalfa, Medicago sativa
Buttercup, Narcissus 'John Evelyn,' 'Unsurpassable' 'King Alfred' and 'Ice Follies'
Peonies, *Paeonia species (some)
Rhubarb, Rheum rhabarbarum
Trees
Silver Maple, Acer saccharinum
European Alder, Alnus glutinosa
White Birches, Betula species
Northern Hackberry, Celtis occidentalis
Apples and Crabapples, Malus species
Norway Spruce, Picea abies
Mugo Pine, Pinus mugo
Red Pine, Pinus resinosa
Eastern White Pine, Pinus strobus
Basswood, Tilia heterophylla
Shrubs
Red Chokeberry, Aronia arbutifolia
Hydrangea species
Mountain Laurels, Kalmia species
Privet, Ligustrum species
Amur Honeysuckle, Lonicera maackii
Brush Cinquefoil, Potentilla species
Rhododendrons and Azaleas, **Rhododendron species (most)
Blackberry, Rubus allegheniensis
Lilacs, Syringa species and cultivars
Yew, Taxus species
Blueberry, Vaccinium corymbosum
*Viburnum plicatum tomentosum 'Mariesii'
Annuals and Vegetables Transplants
Cabbage, Brassica oleracea capitata
Peppers, Capsicum species (some)
Tomatoes, Lycopersicon esculentum
Flowering Tobacco, Nicotiana alata
Petunia species and cultivars
Eggplant, Solanum melongena
Potato, Solanum tuberosum
double-flowered cole vegetables
*Cultivars of some species may survive but will do poorly.

The authors express their appreciation to Drs. M. Scott Biggs, Department of Horticulture and Crop Science, and Harry Hoitink, Department of Plant Pathology, for their review and additional comments.



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All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.

TDD No. 800-589-8292 (Ohio only) or 614-292-1868


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Brenda,
Thank you so much for posting this list! I am going to print it out and save it.
This is just what I wanted to know: They say that walnut leaves and even bark are safe to compost. I did not know this. However, I suspect it takes longer than they say to get rid of root toxicity.
I did not know that the butternuts also contain the juglone chemical.
I have noticed that walnut trees come up and kill apples fast, so you do have to control walnuts to grow apples.

That list names basswood and blackberry as being juglone intolerant, which is definitely untrue. I've got both of those thriving within the dripline of black walnuts. I've never been able to find a list that didn't have errors.

peace

oskar if you look at the list of things that grow near walnuts they have blackberry listed there..

some items are on both lists of things that are and are not tolerant..

there are some things that tolerante Juglone under certain conditions as well..some things will only tolerate Juglone if they have certain companions with them, but that is a different study

Having fertile soil will go a long way to improve the chance to have anything growing near walnut.

I've written a post about walnut guild:
http://designerecosystems.com/2014/10/28/the-best-permaculture-walnut-guild-and-how-to-produce-more-food-from-a-smaller-area/

On thing I think is wrong, is to recommend growing tomatoes near walnut. The plant will struggle, and there is a difference between "growing" and giving reasonable yields.

So how far away should black walnut trees be from a fruit food forest???

@Danielle Venegas

It depends... Make sure your garden is well irrigated and fertilized, then the distance will lower as teh walnut will not "send" roots far away.

Also think about the area between the black walnut as a place where you will plant different fruit trees (mulberry, seabery, gumi...). Maybe use this area to plant more nitrogen fixers, so you will not have to put as much nitrogen fixers in the area where you want fruit trees susceptible to juglone.

Wojciech Majda wrote:@Danielle Venegas

It depends... Make sure your garden is well irrigated and fertilized, then the distance will lower as teh walnut will not "send" roots far away.

Also think about the area between the black walnut as a place where you will plant different fruit trees (mulberry, seabery, gumi...). Maybe use this area to plant more nitrogen fixers, so you will not have to put as much nitrogen fixers in the area where you want fruit trees susceptible to juglone.

I knew my walnut trees couldn't be with the fruit trees so I planted them on the other side of the driveway. I'd say they are about 100 feet from the nearest fruit tree. Too little??

That should be fine Danielle.