permaculture

["Dominic & Helen Dring" <thedrings@telefonica.net>]

Rob and/or anyone else in the know,
Rob Scott wrote of the antirespiritory quality of juglone.
I live on an irrigated smallholding in Andalucia, Spain.  We have a number
of walnut trees.  My son (11 years) has asthma.  His asthma has not improved
(and often seems worse) since moving here from smoggy southern England.  The
air here appears beautifully clean.  We know he has a strong allergy to cats
and horses (brief contact with either sets off a bad ashma attack) but he
doesn't often have direct contact.  I don't  know what type of walnut we
have, whether it is Black Walnut (the nuts turn black when old and exude a
black stain when fresh nuts are punctured).  Could there be any connection
between our trees and my sons breathing?  Does anyone have any other ideas
for causes or cures?
Apologies for my babble and thanks in anticipation of any responses.
Dominic Dring
Finca Mamaita
Cortes de la Frontera
Andalucia
SPAIN

----- Original Message -----
From: <robscott@freeshell.org>
To: <permaculture@lists.ibiblio.org>
Sent: Tuesday, February 15, 2005 10:02 PM
Subject: [permaculture] Black Walnut Guild


>
> In response to the disparaging comments about Black Walnut, I'm posting my
> research on Black Walnut ecology and companion planting. A list of
> productive species for Black Walnut understory appears at the bottom.
>
> Rob Scott
> Urbana Permaculture Project
> Urbana, IL
>
> Black Walnuts (Juglans nigra) and Hackberry (Celtis occidentalis) occur
> together naturally, both are reported to be allelopathic, for separate but
> overlapping sets of plants. In warmer climates, the closely related
> Sugarberry (Celtis laevigata) would be a more fruitful associate.
>
> Why is Black Walnut toxic?
>
> Black Walnuts produce a toxin called "juglone" in all parts of the tree.
> It is an antirespiratory compound with a phenolic ring. It probably
> evolved to deter insect pests, not plants or humans. Fishermen have used
> ground up walnut hulls to attract fish to the surface of the water; the
> juglone slows fish respiration and the fish come to the surface to
> breathe. Juglone in leaf litter degrades in about 2 days, so raked up leaf
> mulch is not toxic. Walnut tree roots constantly release juglone, and this
> is why nearby plants often die.
>
> What companion plants help Black Walnut grow?
>
> Control experiments in Illinois found that Autumn Olive (Elaeagnus sp.)
> work better as a symbiont for promoting Black Walnut growth than Black
> Locust (Robinia pseudoacacia). Both fix nitrogen, but the Autumn Olive
> doesn't compete with the Black Walnut as much and seems to reduce deer
> browse. The net effect of Black Locust was to set back Black Walnut by
> shading. Degraded sites will yield different results as Black Locust
> better restores depleted soils.
>
> What naturally grows under Black Walnut?
>
> Redbud (Cercis canadensis), Pawpaw (Asimina triloba), and Spicebush
> (Calycanthus occidentalis) grow as understory shrubs under Black Walnut
> naturally in Central Illinois. Ground level  wildflowers are no less
> abundant under Black Walnuts than in other natural forest communities.
>
> Does Black Walnut create a lot of shade?
>
> Black Walnuts let through a lot of sunlight. Shade is "dappled" even after
> leaves have fully emerged. Bud break in Black Walnut occurs in late
> spring, allowing sun penetration to the forest floor for a few months
> before leafing out. A rust fungus commonly causes anthracnose in Black
> Walnut leading to early leaf-drop and dormancy in the fall, adding another
> month of full sun penetration. Understory shrubs have been shown to reduce
> anthracnose infection by breaking the ground-to-leaf cycle.
>
> What productive plants can grow under Black Walnut?
>
> (in no particular order)
> American Black Currant - Ribes americanum
> European Currant - Ribes nigra, Ribes rubrum, Ribes alba
> Missouri Gooseberry - Ribes missouriensis
> American Elderberry - Sambucus canadensis
> Black Raspberry - Rubus ideaus
> Siberian Pea Shrub - Caragana arboescens
> Mulberries - Morus nigra, Morus alba
> Alpine Strawberries - Fragaria vesca
> Goldenseal - Hydrastis canadensis
> Wild Ginger - Asarum canadense
> Pawpaw - Asimina triloba
> Redbud - Cercis canadensis - legume
> Bamboo - Phyllostachys spp.
> "Rose of Sharon" Hibiscus - Hibiscus Syriacus
> Lamb's Quarters - Chenopodium alba
> Catnip - Nepata cataria
> Daylily - Hemerocallis sp
> Sunchokes - Helianthus tuberosa
>
> This is a good way to control the spread of sunchokes, and the tubers are
> of fine size and quality even when shade grown. Dandelions, Violets and
> Creeping Charlie have also grown naturally in Illinois Black Walnut
> Guilds. Toby Hemenway mentions Woldberry (Lycium spp) in Gaia's Garden for
> growing near Walnut, but it doesn't grow well in Illinois.
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