Juglone- Trees and Shrubs Resistant to Juglone


Juglone in black and white walnut trees can cause some gardening problems. Don’t despair if walnut trees are killing your other plants, especially Juglan nigra varieties. Here are some ways to help your plants survive the terrors of juglone. Juglone is a toxic chemical found in the roots of walnut trees which affects the growth of other organisms and plants nearby. If you want to avoid the juglone problem altogether, choose from the list of tree and shrubs that are resistant to juglone.

"Juglone Resistant Trees and Shrubs"

Black walnut trees contain high levels of juglone

"Juglone"

Juglone is a toxic substance

Steps to help with juglone

1. Try to clean up any debris immediately as these trees may shed a massive leaf or two intermittently throughout the growing season. Don’t wait until fall foliage drops to pick them up. Any contact that the parts of the tree make with the soil, will affect the plants growing nearby. You should also gather the nuts as soon as they fall as the toxins in the husks increase as the nuts ripen.

2. Try to make sure that your soil contains a lot of organic matter to improve its health, aeration, and drainage. Micro-organisms in compost may also consume some of the leached juglone for energy and somewhat neutralizes the substance. You can also regularly add a top layer of compost to increase your soil’s organic matter, Make sure that you do not use walnut debris in any form as a mulch until it has thoroughly decomposed in a hot compost pile.

3. Avoid plants like apple trees, mountain laurels, rhododendrons, blueberries, and white birches that can die from the effects of juglone. Instead, you should learn which plants are resistant to juglone.

Trees and shrubs resistant to Juglone:

Trees

American arborvitae, Thuja occidentalis

American holly, Ilex opaca

Carolina silverberry, Halesia carolina

Dogwood, Cornus species

Eastern redbud, Cercis species

Golden raintree, Koelreuteria paniculata

Hawthorn, Crataegus species

Japanese maple, Acer palmatum

River birch,Betula nigra

Serviceberry, Amelanchier x grandiflora

Shrubs

Blackhaw viburnum, viburnum prunifolium

Daphne, Daphne species

Forsythia, Forsythia species

Juniper, Juniperus species

Lilac, Syringa species

Ninebark, Physocarpus opulifolius

Rose of sharon, Hibiscus syriacus

Spicebush, Lindera benzoin

Wild hydrangea, Hydrangea arborescens

Witch hazel, Hamamelis species

 

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