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Black Walnut ToxicityJuglans nigra & Juglans cinerea

Occasionally, clients will call our offices with complaints that they have an area in their yard where they just can’t seem to grow anything. One of the questions we ask is “Is there a black walnut tree nearby?” Black walnut (Juglans nigra) and a related species, Butternut (Juglans cinerea) produce juglone, a substance that is poisonous to a wide variety of plants. The problem exists in all areas of the soil around the trees.

Black walnut and Butternut trees are not recommended for use in residential landscapes because of the difficulty in growing other plants nearby. They are best suited to wide-open, natural areas where their beauty and fast growth rate can be appreciated, their nuts can provide food for wildlife, and where they will not interfere with the health of other desirable plants.

They symptoms of juglone poisoning includes yellowing or browning of the leaves of affected plants, stunted, twisted growth or a failure to grow, sudden wilting and death. As Black Walnut and Butternut trees grow larger and their roots spread, sensitive plants further and further away from the main trunks of these trees will begin to decline in health and may eventually die.

Not all plants are affected by this toxicity problem. Some plants have a natural resistance to juglone and can survive near and even under these trees. Some plants do not grow deep roots, and more shallow root systems seem to be more resistant as well.

Juglone is present in all parts of black walnut and butternut trees. Care needs to be taken when disposing of the nuts, bark, and leaves of these types of trees. Do not use these materials for mulch around plants that are not tolerant of juglone.

Black Walnut fruits and foliage.

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Black Walnut form.

Identification

Black Walnut Toxicity

Black Walnut Toxicity

BarberryNew Jersey TeaWhite FringetreeDogwoodAmerican HazelnutDaphneEuonymusForsythiaWitchhazelRose of SharonSmooth HydrangeaOakleaf HydrangeaSt. John’s WortKerriaLilacMost HoneysucklesSumacRugosa RoseWillowElderberryMost Viburnums

Berberis sp.Ceanothus americanusChionanthus virginicus

Cornus sp.Corylus americanus

Daphne sp.Euonymus sp.

Forsythia sp.Hamamelis sp.

Hibiscus syriacusHydrangea arborescensHydrangea quercifolia

Hypericum perfoliatumKerria japonica

Syringa sp.Lonicera sp.

Rhus sp.Rosa rugosa

Salix sp.Sambucus sp.Viburnum sp.

Shrubs

PerennialsHollyhockJack-in-the-PulpitAsterAstilbeLady Fern & Ghost FernFeather Reed GrassTufted Hair GrassBellflowerWild SennaConeflowerSpotted Joe Pye WeedPrairie SmokeJapanese Forest GrassDaylilyCoralbellsMany HostasBottlebrush GrassSiberian IrisShasta DaisyGreat Blue LobeliaVirginia BluebellsBeebalmSensative FernCinnamon FernPeonyPhloxObedient PlantSolomon’s SealChristmas FernLungwortRudbeckiaHardy SalviaStonecropGoldenrodLamb’s EarPurple Meadow RueSpiderwortIronweed

Alcea sp.Arisaema triphyllum

Aster sp.Astilbe sp.

Athyrium sp.Calamagrostis sp.Deschampsia sp.

Campanula sp.Cassia hebecarpa

Echinacea purpureaEupatorium maculatum

Geum triflorumHakonechloa macra

Hemerocallis sp.Heuchera sp.

Hosta sp.Hystrix patula

Iris sibericaLeucanthemum sp.

Lobelia siphliticaMertensia virginica

Monarda sp.Onoclea sensibilis

Osmunda cinnamomeaPaeonia sp.

Phlox sp.Physostegia virginiana

Polygonatum sp.Polystichum sp.Pulmonaria sp.

Rudbeckia sp.Salvia sp.

Sedum sp.Solidago sp.

Stachys sp.Thalictrum dasycarpum

Tradescantia sp.Vernonia fasciculata

VinesClematisEngelmann Ivy

BittersweetHoneysuckle VineThicket Creeper

Clematis sp.Parthenocissus quinquifolia

var. EngelmannCelastrus scandens

LoniceraParthenocissus inserta

Updated 2015

Plants Observed to Grow Under Black Walnut and Butternut Trees

TreesMaplesJapanese MapleSpeckled AlderMusclewoodCommon HackberryEastern RedbudPagoda DogwoodShagbark HickoryNorthern CatalpaHawthornHoneylocustAmerican PlumOrnamental PearOakWillowElms

Acer sp.Acer palmatum

Alnus rugosaCarpinus caroliniana

Celtis occidentalisCercis canadensis

Cornus alternifoliaCarya ovataCatalpa sp.

Crataegus sp.Gledistsia sp.

Prunus americanaPyrus calleryana

Quercus sp.Salix sp.

Ulmus sp.

ConifersArborvitae/White CedarJuniperCanadian Hemlock

Thuja sp.Juniperus sp.

Tsuga Canadensis

GroundcoversBugleweedWild GingerSweet WoodruffPachysandraStonecrop

Ajuga reptansAsarum canadenseGalium odoratum

Pachysandra terminalisVinca minor