Black Walnut Toxicity

From the Department of Horticulture – Michigan State Universityblack-walnut-tree

The black walnut (Juglans nigra) contains the phytotoxin juglone which can cause stunting, death, or wilting in many plants when they are planted nearby. Juglone (the substance produced by the tress) is present on the roots, leaves, fruits, and branches of the plant. Other species of the walnut family also contain juglone (the substance produced by the tree) but on lesser concentrations. They are, in descending order of concentration: English Walnut (Juglans regia), butternut (J.cineraria), hickory (Carya ovata), and pecan (C. illinoinensis).

The average limit of the toxic zone from a mature tree is 50 to 60 feet, but plants as far away as 80 feet have also been injured. The use of black walnut sawdust, leaves, crushed husks as mulch or in compost can also have toxic results, especially on very susceptible plants such as the tomato.  While some plants are susceptible to juglone, others are not and can even thrive in the area of black walnuts.

The following lists plants which have been shown to be not susceptible and those susceptible to black walnut toxin.

Plants Resistant to Walnut Toxicity (* Stocked at RSF)

Trees

Acer negundo (Box Elder)
Acer nigrum (Black Maple)
Acer palmatum (Japanese Maple)*
Acer palmatum-Dissectum (Japanese Maple)*
Acer rubrum (Red Maple)
Acer saccharum (Sugar Maple)
Aesculus glabra (Ohio Buckeye)*
Ailanthus glandulosa (Tree of Heaven)
Asimina triloba (Papaw)
Betula lenta (Black Birch)
Betula nigra (River Birch)*
Caraya sp. (Hickory)
Catalpa bignonoides (Common Catalpa)*
Celtis occidentalis (Common Hackberry)
Cercis canadensis (Redbud) *
Cornus Florida (Flowering Dogwood)*
Crataegus spp. (Hawthorn)
Cydonia oblonga (Quince)
Fagus grandifolia (Beech)
Gleditsia triacanthos (Honey Locust)
Halesia carolina (Carolina Silverbell)*
Juniperus virginiana (Red Cedar)
Koelreuteria paniculata (Goldenrain-tree)
Liquidamber styraciflua (Sweetgum)
Liriodendron tulipifera (Tulip tree)
Nyssa sylvatica (Black Gum)
Oleaceae spp. (Autumn olive)
Picea abies (Norway Spruce)*
Pinus jeffreyi (Jeffrey Pine) *
Pinus virginiana(Scrub Pine)
Plantanus occidentalis (Sycamore)
Prunus serotina (Black Cherry)
Pyrus calleryana (Callery Pear)
Pyrus coronaria (American Crab)*
Querus alba (White Oak)
Querus borealis (Red Oak)
Quercus imbricaria (Shingle Oak)
Quercus rubra (Northern Red Oak)
Querus ventutina (Black Oak)
Rhus hirta (Staghorn Sumac)
Robinia pseudoacacia (Black Locust)
Sassafrass variifolium (Sassafrass)
Tilia platyphyllas (Bigleaf Linden)
Tsuga canadensis (Canadian Hemlock)*
Ulmus americana (American Elm)
Viburnum prunifolium (Black Haw)

Shrubs& Vines

Berberis canadensis (American Barberry)
Benzoin aestivale (Spicebush)
Celastrus scandens (Climbing Bittersweet)
Clematis terniflora (Sweet Autumn Clematis)
Clematis virginiana (Virgin’s Bower)
Cornus alternifolia (Alternate-leaved Dogwood)
Corylus Americana (Hazelnut)
Euonymus europaea (European spindletree)
Euonymus hamiltonianus (Yeddo Euonymus)
Forsythia spp.
Hydrangea arborescens (Wild Hydrangea)
Hypericum prolificum (Shrubby St.John’s wort)
Kerria japonica (Kerria)
Kerria japonica ‘Pleniflora’ (Double-flower kerria)
Lonicera maackia (Amur honeysuckle)*
Lonicera tatarica (Tatarian honeysuckle)
Lonicera xylosteum (European fly honeysuckle)
Psedera quinquefolia (Virginia Creeper)
Rhus glabra (Smooth Sumac)
Rhus copallina (Dwarf Sumac)
Rhus toxicodendron (Poison Ivy)
Ribes spp. (Currant)
Rosa spp. (Wild Rose)
Sambucus canadensis (Common or American Elderberry)
Smilax spp. (greenbrier)
Thuja occidentalis (American arborvitae)
Viburnum acerifolium (Maple-leaved Viburnum)
Viburnum lantana (Wayfaring-tree Viburnum)
Vitis spp. (Wild Grape)

Herbaceous Plants

Achillea millefolium (Common yarrow)
Agrostis alba (Redtop)
Ambrosia spp. (Ragweed)
Andropogon virginicus (Broomsedge)
Anemone spp. (Thimbleweed)
Antennaria spp. (Pussy’s Toes)
Arisaema triphyllum (Jack-in-the-Pulpit)
Asarum virginicum (Wild Ginger)
Asclepias syriaca (Common milkweed)
Asplenium platyneuron (Ebony Spleenwort)
Aster spp. (Aster)
Athryium thelypteroides (Silvery Spleenwort)
Bidens spp. (Beggar-ticks)
Brassica spp. (Mustard)
Campanula americana (Tall Bellflower)
Carex spp. (Sedges)
Cassia marilandica (Wild Senna)
Cassia nictitans (Wild Sensitive Plant)
Cerastium vulgatum (Mouse-ear Chickweed)
Chrysanthemum leucanthemum (Ox-eye Daisy)
Chyrsanthemum spp. (Shasta daisy)
Cichorium intybus (Chicory)
Cirsium spp. (Thistle)
Claytonia spp. (Spring Beauty)
Collinsonia canadensis (Rich-weed)
Commelina communis (Virginia Day flower)
Convolvulus arvensis (Field Bindweed)
Crocus spp.
Cuphea petiola (Clammy Cuphea)
Cuscuta spp. (Dodder)
Daucus carota (Wild carrot)
Dentaria spp. (Toothwort)
Desmodium spp. (Tick Trefoil)
Dianthus armeria (Deptford Pink)
Elephantopus spp. (Elephant’s Foot)
Equisetum arvense (Common horsetail)
Erigeron annuus (Daisy Fleabane)
Erigeron philadelphicus (Philadelphia Fleabane)
Eupatorium coelestinum (Mist-flower)
Eupatorium purpureum (Joe-Pye Weed)
Galium spp. (Bedstraw)
Geranium spp. (Wild Geranium)
Geum spp. (Avens)
Hedeoma pulegioides (Pennyroyal)
Helenium spp. (Sneezeweed)
Helianthus spp. (Sunflower)
Hemerocallis spp. (Daylily)
Heuchera spp. (Alumroot)
Hieracium spp. (Hawkweed)
Hypericum spp. (St. John’s-wort)
Impatiens spp. (Jewelweed)
Iris spp.
Lactuca spp. (Wild Lettuce)
Leonurus cardiaca (Motherwort)
Lespedeza spp. (Bush Clover)
Liriope spp.
Lobelia inflata (Indian Tobacco)
Lobelia siphilitica (Great Lobelia)
Lobelia spicata (Spiked Lobelia)
Lycopodium complanatum var. flabelliforme (Ground pine)
Malva rotundifolia (Common Mallow)
Malus spp. (Crabapple) *
Melilotus spp. (Sweet Clover)
Menispermum canadense (Moonseed)
Mentha piperita (Peppermint)
Monarda fistulosa (Wild Bergamot)
Monarda punctata (Horsemint)
Muhlenbergia schreberi (Nimblewill)
Muscari sp. (Grape Hyacinth or Bluebells)
Nepeta hederacea (Gill-over-the-ground)
Oenothera spp. (Evening Primrose)
Oxalis spp. (Wood Sorrel)
Pachysandra spp.
Phleum pratense (Timothy)
Physalis spp. (Ground cherry)
Pilea pumila (Clearweed)
Plantago major (Common Plantain)
Plantago lanceolata (English Plantain)
Podophyllum peltatum (Mayapple)
Polimoniaceae spp. (Phlox)
Polygala sanguinea (Milkwort)
Potentilla canadensis (Common Cinquefoil)
Prenanthes spp. (Rattlesnake-root)
Prunella vulgaris (Heal-all)
Pycnanthemum spp. (Mountain mint)
Ranunculus spp. (Crowfoot)
Rudbeckia hirta (Brown-eyed Susan)
Rumex spp. (Dock)
Scilla siberica (Blue Squill or Siberian Squill)
Sedum ternatum (Stonecrop)
Senecio aureus (Golden Ragwort)
Smilacina racemosa (False Spikenard)
Solidago spp. (Goldenrod)
Spiranthes gracilis (Slender Ladies Tresses)
Taraxacum spp. (Dandelion)
Trifolium hybrifolium (Alsike Clover)
Trifolium pratense (Red Clover)
Trifolium repens (White Clover
Trifolium spp. (Hop Clover)
Trillium spp.
Uvularia perfoliata (Bellwort)
Verbascum blattaria (Moth Mullein)
Viola spp. (Violet)
Verbascum thapsus (Common Mullein)
Vernonia spp. (Ironweed)
Veronica officinalis (Common Speedwell)
Woodsia obtusa (Obtuse Woodsia)

Fruits

Rubus occidentalis (Black Raspberry)

Vegetables/Crops

Allium cepa (Onions)
Beta vulgaris (Beets)
Dioscorea villosa (Wild Yam)
Glycine max (Soybean)
Pastinaca sativa (Parsnips)
Phaseolus spp. (Lima beans)
Phaseolus spp. (Snap beans)
Triticum aestivum (Wheat)
Zea mays (Corn)

Grasses

Arrhenatherum elatius (Tall Oatgrass)
Bromus spp. (Brome grass)
Dactylis glomerata (Orchardgrass)
Holcus mollis “Variegatus” (Velvet grass)
Panicum clandestinum (Deer Tongue Grass)
Poa compressa (Canada Bluegrass)
Poa pratensis (Kentucky Bluegrass)

Ferns

Athryium asplenioides (Lowland Lady)
Botrychium dissectum (Dissection Grape Fern)
Botrychium dissectum var. obliquum (Common Grape Fern)
Dennstaedtia punctilobula (Hay-scented)
Dryopteris intermedia (Intermediate Shield Fern)
Dryopteris marginalis (Marginal Shield)
Onoclea sensibilis (Sensitive Fern)
Osmunda cinnamomea (Cinnamon Fern) *
Polystichum acrostichoides (Christmas)


PLANTS SUSCEPTIBLE TO WALNUT TOXICITY

Trees

Acer saccharinum (Silver Maple)
Aesculus octandra (Sweet Buckeye)
Amelanchier canadensis (Serviceberry)
Betula alba (White Birch)
Betula Lutea (Yellow Birch)
Betula nigra (River Birch)
Carpinus caroliniana (American Hornbeam)
Castanea dentata (Chestnut)
Diospyros virginiana (Persimmon)
Elaeagnus angustifolius (Russian olive)
Fraxinus americana (White Ash)
Fraxinus nigra (Black Ash)
Hamamelis virginiana (Witch-hazel)
Ilex opaca (American Holly)
Ilex verticillata (Michigan holly)*
Juglans cinerea (White walnut)
Magnolia acuminata (Cucumber Tree)
Magnolia soulangiana (Saucer Magnolia)
Malus hopa (Hopa Crabapple)*
Malus sp. (Apples)*
Morus rubra (Red Mullberry)
Pinus resinosa (Red pine)
Pinus rigida (Pitch Pine)
Pinus strobus (white pine)
Pinus sylvestis (Scotch pine)
Pinus taeda (Loblolly pine)
Picea abies (Norway Spruce)
Prunus Americana (Wild Plum)
Prunus Pennsylvanica (Fire Cherry)
Quercus stellata (Post Oak)
Quercus coccinea (Scarlet Oak)
Salix nigra (Black Willow)
Sambucus canadensis (Common Elderberry)
Thuja occidentalis (Arborvitae)
Tilia americana (Basswood)
Tilia heterophylla (White Basswood)
Ulmus fulva (Slippery Elm)
Viburnum sieboldii (Siebold Viburnum)

Shrubs & Vines

Alnus rugosa (Smooth Alder)
Aralia spinosa (Hercules’ Club)
Aristolochia macrophylla (Pipe Vine)
Aronia arbutifolia (Red chokeberry)
Azalea sp. (Azalea)
Baptisia australis (Blue False Indigo)
Ceanothus americanus (New Jersey Tea)
Chionanthus virginica (Fringe-tree)
Cornus amomum (Silky dogwood)
Euonymus americanus (Strawberry bush)
Hydrangea sp. (Hydrangea)
Kalmia latifolia (Mountian Laurel)
Larix kaempferi (Japanese larch)
Ligistrum sp. (Privet)
Lonicera canadensis (American Fly Honeysuckle)
Physocarpus opulifolius (Nine-bark)
Pinus mugo (Swiss mountain pine)
Potentilla frutiocosa (Shrubby Cinquefoil)
Prunus tomentosa (Nanking cherry)
Prunus subhirtella Pendula (Weeping Higan Cherry)
Prunus viriniana (Choke cherry)
Pyracantha sp. (Firethorn)
Rhododendron sp. (Rhododendron)*
Rhus canadensis (Fragrant Sumac)
Staphylea trifolia (Bladder Nut)
Syrina sp. (Lilac)
Viburnum dentatum (Arrow-wood)
Viburnum opulus (European Cranberrybush Viburnum)
Viburnum plictum (Double File Viburnum)
Zanthoxylum americanum (Prickly Ash)

Herbaceous Plants/Bulbs

Aquilegia caerulea (Colorado Columbine)
Aquilegia canadensis (Wild Columbine)
Chrysanthemum morifolium (Chrysanthemum)*
Habenaria lacera (Ragged fringed Orchid)
Heuchera spp. (Alumroot)
Lilium (Lily; Enchantment and other Asian (Hybrids)
Narcissus (Narcissus, Daffodil; John Evelyn, Unsurpassable, King Alfred,
Ice Follies, All trumpet and large flat cupped)*
Paeonia sp. (Peony)
Rosa chinensis (Fairy Rose)
Rosa minima (Fairy Rose)
Tulipa (Tulip; Merry Widow, West Point)

Fruits

Gaylussacia sp. (Huckleberry)
Rubus spp. (Blackberry)
Rubus odoratus (Purple Flowering Raspberry)
Vaccinium corymbosum (Highbush Blueberry)
Vaccinium sp. (Blueberry)

Vegetables/Crops

Asparagus officinalis (Asparagus)*
Beta vulgaris (Sugar Beets)
Brassica oleracea var. capitata (Cabbage)
Capsicum annuum (Pepper)
Lycopersicon esculentum (Tomato)
Medicago sativa (Alfalfa)
Solanum melongena esculentum (Eggplant)
Solanum tuberosum (Potato)
Trifolium incarnatum (Crimson clover)

 
Source: MSU Oakland County Extension – Problem Solvers OC280