Juglone in Pecan Leaves Can Harm Plants | Gardener's Path

You may know that many plants don’t grow well – or at all – under walnut trees. This fact has been observed and documented since the first century AD.

But what about pecan trees? Do they have the same effect?

They are members of the same family as walnuts (Juglandaceae), although that doesn’t necessarily mean that they have the same chemical properties.

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Think about the Solanaceae family. Edible plants like tomatoes, eggplants, peppers, and potatoes, and the highly toxic deadly nightshade, are all in the same family.

But yes, pecans can also inhibit the growth of other plants in the vicinity to the extent that you should avoid planting certain species under or near pecan trees.

They die because they are being poisoned!

Both pecans and walnuts produce a family of closely related toxic chemicals. The parent compound is called juglone – or 5-hydroxy-1,4-napthoquinone to be precise.

And there is a reason to be technical.

Focus on the quinone in that name. Quinone is a highly reactive compound that can be dangerous in the presence of oxygen.

So dangerous, in fact, that small amounts can kill a person.

Juglone acts like cyanide and is poisonous to animals, plants, and microbes.

But don’t worry! The leaves, nuts, and roots do not contain high enough concentrations to kill us.

Producing a chemical that inhibits the growth of another plant is known as allelopathy – the poisoning of one plant by another.

The idea is that both pecans and walnuts will have less competition from other plants if they produce a