Willsull.net
Agroforest Syst (2007) 71:185–193DOI 10.1007/s10457-007-9071-8
A review of suitable companion crops for black walnut
Robert Scott Æ William C. Sullivan
Received: 9 May 2006 / Accepted: 16 May 2007 / Published online: 21 June 2007
! Springer Science+Business Media B.V. 2007
Black walnut (Juglans nigra L.) is a
temperate tree grown for nuts and wood, but it isallelopathic to certain plants and animals. We com-
Black walnut (Juglans nigra L.) has a mixed
piled reports of valuable black walnut companion
reputation. On the one hand, it is a valuable tree
crops which may be grown in the short term
crop with beautiful heartwood and delicious nuts. On
(<15 years after planting walnut trees), medium term
the other hand, it is known to produce allelopathic
(15–30 years), and long term (>30 years). There are
chemicals that inhibit the growth of other plants
many black walnut companion cropping systems for
(Willis ). There have been dozens of studies in
the short and medium term, but there are few for the
recent years on black walnut multi-cropping systems,
long term. Companion crops for black walnut serve
but the dominant narrative has remained roughly the
multiple functions, including nitrogen fixation, added
same: black walnut is a long term tree crop,
yields, the development of straight walnut stems, and
allelopathic in general, which at best can be expected
added protection from forest pests such as deer. Black
to permit the co-existence of one additional farm
walnut polyculture is a viable alternative worthy of
yield chosen from a small pool of tolerant species.
further development and implementation.
This paper aims to shift that narrative, to one ofmultiple potential yields, which can recover stand
Allelopathy ! Juglans nigra ! Juglone !
establishment costs and add revenue streams up to the
Permaculture ! Polyculture
day of the timber harvest.
Black walnut is bred for various products (Reid
et al. The maroon-black heartwood is the mostvaluable black walnut yield, which is made intofurniture, veneer, and gunstocks. This lucrative
commodity was once raised as a ‘‘retirement crop'':
Department of Educational Policy Studies, University of
farmers would sell an old black walnut stand to fund
Illinois at Urbana - Champaign, 360 Education Bldg.,
their retirement. The nuts of the tree are edible, and
1610 S. 6th St., Champaign, IL 61821, USA
black walnut has been described as ‘‘the most
e-mail:
[email protected]
dependable nut plant for Illinois'' (Meador et al.
). Nut crops can be produced by young trees, but
Department of Natural Resources and Environmental
yields are influenced by site, tree variety, and
Sciences, University of Illinois, 1101 W. Peabody, Room
management practices. The market for black walnuts
350, MC-635, Urbana, IL 61801, USAe-mail:
[email protected]
is not as well developed as that for carpathian walnuts
Agroforest Syst (2007) 71:185–193
(J. regia L.). Black walnut sap may be processed into
that there is a veritable ‘‘guild'' of species which will
a sweet syrup comparable to maple syrup (Matta et al.
live with the walnut forest in all stages of its
), but the sap is more dilute in black walnuts.
development. In this paper, we briefly introduce the
Black walnut syrup is novel, but trivial in economic
buildup of juglone during the establishment of black
terms. The most valuable commercial yield of the
walnut plantings, and describe reports of added yields
black walnut, its heartwood, is not ready for harvest
of food and wood, nitrogen fixation, and tree
until decades after stand establishment. If black
protection which may be attained in the short and
walnut production is going to produce value in the
medium term. In doing so, we show that a black
short term, additional crop species are required,
walnut polyculture is not only possible, but econom-
especially species that can produce economic value
ically viable as well.
during the first 20 years after establishment of theblack walnut stand. The major barrier to black walnutpolyculture is its reputation as an allelopath.
Spatial and temporal buildup of juglone
Black walnut and other members of the family
Juglandaceae have long been known to produce an
Several factors influence the accumulation of juglone
allelopathic compound known as ‘‘juglone'' which
in a growing area, including rhizosphere interactions,
inhibits the growth of several other species of plant
uptake by soil organisms, adsorption of juglone to
(Davis ; Willis ). Roots, leaves, and hulls
soil particles, and movement in the soil solution.
contain large quantities of harmless hydrojuglone,
Living black walnut trees exude juglone into the
which may be oxidized to juglone (Segura-Aguilar
rhizosphere (Bertin et al. which likely explains
et al. ), then transferred to neighboring plants
reports that allelopathy can continue after walnut tree
primarily as a root exudate in the rhizosphere of the
removal, especially if the stumps are not killed
black walnut trees (Bertin et al. In susceptible
(Piedrahita ). A species of Pseudomonas has
plants, juglone interferes with respiration and photo-
been identified that can metabolize juglone (Schmidt
synthesis (Hejl et al. ). Affected plants turn
) potentially providing a juglone sink, but it is
brown, wilt, and die. Most vegetable crops are
unlikely that these bacteria prevent plant exposure to
vulnerable to juglone toxicity (Crist and Sherf
the juglone. Juglone in solution may also be adsorbed
), as are some fruit tree species and all members
to soil particles or organic matter (Willis Soil
of the plant family Ericaceae (Brooks ). In the
moisture regime seems to augment the effects of
animal kingdom black walnut hulls are responsible
juglone exposure. A study with white pine (Pinus
for triggering lamnitis, an often fatal hoof condition
strobus L.) suggests that poorly drained soils may
in horses (Thomsen et al. which may harm fish
exacerbate the effects of juglone toxicity: pines
(Radix et al. ) and repel ants and flies (Walker
growing near black walnut on a well drained soil
). Common midwest crops which are susceptible
grew tall, while pines growing near black walnut on a
to the presence of black walnut include corn and
poorly drained soil died (Fisher ). Though
soybeans (Jose and Gillespie Hejl and Koster
juglone accumulation is dynamic, any area planted
), wheat and alfalfa (Bertin et al.
with black walnuts may potentially show symptoms
What types of crops can be raised in black walnut
of allelopathy.
plantations in the midwestern United States? Lists of
How many years after planting black walnut do
‘‘compatible'' and ‘‘incompatible'' species are avail-
toxic juglone effects appear? Various estimates
able in extension publications (Crist and Sherf ;
include 12–25 years (Rietveld ; Rink
Funt and Martin Baughman and Vogt
15–20 years (Dawson et al. ); or 12–15 years
but they often contradict each other (Gordon ;
(Beineke ). A high-intensity planting of black
Anonymous ), and are not clearly supported by
walnut (5.5 m · 5.5 m) interplanted with juglone-
scientific literature. Still, this is the most wide-
sensitive Alder trees (Alnus glutinosa [L.] Gaertn.)
ranging information available on the subject, and it
resulted in toxic effects linked to juglone after only
has been generated by experienced and professional
5 years (Bohanek and Groninger Plantations
growers. Our detailed assessment of extension liter-
designed for nut harvesting and other agroforestry
ature and of the published scientific literature shows
practices such as pasture may be spaced closely
Agroforest Syst (2007) 71:185–193
within rows and widely between rows. For instance,
aboveground competition for light, probably juglone
60 · 300 spacing gives 242 trees per acre while
(Jose and Gillespie The concentration of
creating a space between rows in which juglone
juglone in the soil, varies as a function of the
accumulates less quickly (Baughman and Vogt
distance from the rows. In one study, juglone
). Given the caveat that different spacings will
decreased in concentration by 80% at a distance of
produce different rates of juglone accumulation in the
4.25 m from a row of 10 year old black walnut trees
area between the walnut trees, we have designated
(Jose and Gillespie When juglone was added
three periods of juglone accumulation at 15 year
to hydroponically grown corn and soy in the same
intervals (see Table
concentration found in the alley cropping study, therewere significant inhibitory effects on plant growth(Jose and Gillespie Later work isolated the
Short term: multicropping during stand
mechanisms by which juglone disrupts corn and soy
growth (Hejl and Koster Annual crops may beviable between rows of black walnut for up to 5–
Immediately after black walnut seedlings are planted,
10 years, but probably not longer.
the area between the rows may be planted with
An interplanting of trees may help produce straight
juglone-sensitive crops, but after 10–15 years the
black walnut trunks while adding a short to medium
juglone and shade will put constraints on what may
term yield of non-walnut timber. European Black
be grown. In the first few years of growth, Black
Alder (Alnus glutinosa L.), was planted simulta-
Walnut will grow a deep taproot and put on 12@–18@
neously with Black Walnut as a nitrogen fixing nurse
of top growth (30–40 under intensive culture) annually
crop with an added yield of harvestable pole wood, in
(Rink ). Full sun is available for roughly 5–
an Illinois-based study (Bohanek and Groninger
7 years, and it would not be unlikely to see juglone
). The Alder trees would be completely killed
affecting sensitive species by the tenth year. Our
by the level of juglone released by a 20-year-old
research suggests that it is prudent to treat the 10–
Black Walnut, so wood harvests must commence
15 year old black walnut stand as a transition period
between 5 years and 15 years after establishment. The
to a more shady and allelopathic medium term.
authors claim that the alder sale could pay for the cost
Studies on short term companion plants for black
of establishing the Black Walnut stand if the alders
walnut have therefore included juglone-tolerant trees
are harvested in well-timed thinnings between 4 years
and livestock, pasture and forage, and all sorts of
and 19 years after stand establishment (Bohanek and
annual produce for the period just after the trees are
There is evidence that short term planting of
Typical midwest annual crops may be planted
livestock forage or pasture in black walnut planta-
between widely spaced rows of black walnut seed-
tions do not restrict livestock growth, and that
lings. Good walnut sites may also be good soybean
livestock manures may benefit the adolescent walnut
and wheat sites, though shade has been reported to
trees. A pine-walnut plantation with annual ryegrass
affect these crops after 7 years, even with the rows
(Lolium multiflorum Lam.) and cereal rye (Secale
spaced 40 feet apart (Burde ). Corn has been
cereale L.) between the rows as heifer pasture,
raised between rows of black walnut, but it has also
produced approximately 80% of the forage produced
been demonstrated that after 10 years corn produc-
in a control plot without trees, but beef heifer average
tivity is reduced by something other than the
daily weight gain was equal for both treatments
Table 1 Three phases of black walnut stand development
Wood, nuts, sap, shade
Agroforest Syst (2007) 71:185–193
(Kallenbach et al. This suggests that beef
candidates for interplanting with black walnut in the
producers likely would not sacrifice livestock pro-
first few years, and a clever application of this fact
duction when they graze animals under 6–7 year old
could set the stage for a second phase of yields during
pine and walnut trees compared to open pasture.
the medium term.
After chicken manure was applied as a fertilizer to ayoung (3-year-old) Black Walnut plantation in Mis-souri, total height and leaf nitrogen concentrationsincreased during the summer, suggesting that poultry
Medium term: farming amongst mature trees
manure is valuable as a fertilizer during establish-ment of young walnut plantations (Ponder et al.
There are several medium term crops that can provide
). In addition to being a suitable environment for
valuable functions such as nitrogen fixation, and add
poultry, a modular or free-range chicken pasture
yields such as wood 15–30 years after stand estab-
might also benefit young black walnut trees.
lishment (see Table Species living in the black
Young black walnut plantations have been used to
walnut stand during this period must be tolerant of
grow forage for farm animals to eat off site, and
juglone and shade. Even with widely spaced rows,
shade (not juglone) seems to be the main issue
shade is considerable after 15 years. The woody
limiting productivity. Fescue (Festuca arundinacea
species listed below might best be planted simulta-
Schreb.) grown in 7–8 year old black walnut stands
neously with the black walnuts, so that they grow up
produced significantly more forage in medium den-
with the black walnut and develop straight stems,
sity stands (7.3 m between rows) versus low or high
while receiving enough sunlight to produce yields
density stands (14.6 m and 1.8 m between rows,
such as fruit or bolewood. Animal species such as
respectively) (Buergler et al. ). A comparison of
heifers and hens benefit from partial shade available
overall forage yields in fescue fields planted with
in the adolescent walnut stand. Most medium term
black walnut and honey locust (Gleditisia triacanthos
species could also be raised in the short term, but the
L.) showed that forage production decreased more
available reports focus on older stands.
dramatically under high density Honey Locust than
Several soft fruit species are compatible with black
under high density Black Walnut (Buergler et al.
walnut, and can make good use of the transitional
medium term phase of the walnut stand. A 1951
There are a handful of vegetable crops that are
paper summarized 12 years of surveying plant species
reportedly tolerant of juglone, including onions
found growing within and around black walnut trees
(Allium cepa L.) (MacDaniels and Pinnow
in five US states (Brooks ). This is the most
parsnips (Pastinaca sativa L.) (MacDaniels 1974),
methodical survey of naturally occurring black wal-
Jerusalem artichokes (Helianthus tuberosum L.)
nut compatible plants to date. Brooks reported that
(Ross ), sugar beet (Beta vulgaris L.) (Piedrahita
black raspberry (Rubus occidentalis L.) grew under
) and certain species of bean (Phaseolus spp.)
black walnut canopy whereas blackberry (Rubus
(MacDaniels and Pinnow The yields of these
fruticosus L.) only grew outside the crown area;
crops might not be harmed by juglone, but the
currants (Ribes spp.), elderberry (Sambucus canad-
increasingly shady conditions cast by the canopy will
ensis L.), and wild grapes (Vitis spp.) were common
make these annuals less viable in the medium term.
under black walnut canopy, whereas blueberry (Vac-
Managing a black walnut stand in the short term,
cinium spp.) and other ericaceous plants were never
there are at least a few years when the juglone effect
observed near black walnut (Brooks Mulberry
is negligible, before soil juglone concentrations
(Morus spp.) and pawpaw (Asimina triloba [L.]
increase while ground-level sunlight availability
Dunal) trees were also found to be tolerant of black
decreases. Sun-loving juglone-intolerant crops may
walnut whereas apples (Malus spp.) and pears (Pyrus
be leveraged so long as they are not required to return
spp.) were not (Schneiderhan ; Brooks
top yields into the medium term. For this reason,
One grower has claimed multiple sightings of Amer-
annual crops may be the smartest way to leverage
ican Persimmons (Diospyros virginiana L.) growing
some quick revenue from the young black walnut
and producing fruit under black walnut canopy
stand. All temperate climate plants are potential
Agroforest Syst (2007) 71:185–193
Table 2 Short term, medium term, and long term yields which are possible in the presence of black walnut trees
Short term: <15 years
Juglone-intolerant field crops
Grain, produce, forage
Burde Jose and Gillespie
Alfalfa (Medicago sativa)
Cereal rye (Secale cereale)
Kallenbach et al.
Fescue (Festuca arundinacea)
Buergler et al.
Ryegrass (Lolium multiflorum)
Kallenbach et al.
Jerusalem artichokes (Helianthus tuberosum)
Lima bean (Phaseolus lunatus)
MacDaniels and Pinnow
Onion (Allium cepa)
MacDaniels and Pinnow
Parsnips (Pastinaca sativa)
MacDaniels and Pinnow
Sugar beet (Beta vulgaris)
Piedrahita .
Wax bean (Phaseolus vulgaris)
MacDaniels and Pinnow
Cattle (Bos taurus L.)
Kallenbach et al.
Chicken (Gallus gallus)
Meat, eggs, manure
Medium Term: 15–30 years
Fescue (Festuca arundinacea)
Funt and Martin .
Kentucky Bluegrass (Poa pratensis)
Orton and Jenny Brooks
Piedrahita ; Funt and Martin .
Red Clover (Trifolium pratense)
Timothy (Phleum pratense)
MacDaniels and Pinnow Boes .
White clover (Trifolium repens)
Piedrahita ; Boes
Black Raspberry (Rubus occidentalis)
Brooks ; MacDaniels and Pinnow
Piedrahita ; De Scisciolo et al. Fuchs .
Currant (Ribes spp.)
Brooks ; Anonymous
Elderberry (Sambucus canadensis)
Brooks ; Anonymous
Mulberry (Morus spp.)
Brooks ; Mollison .
Pawpaw (Asimina triloba)
Brooks ; Anonymous
Persimmon (Diospyros virginiana)
Autumn olive (Elaeagnus umbellata)
Black locust (Robinia pseudoacacia)
European alder (Alnus glutinosa)
Bohanek and Groninger
Russian olive (Elaeagnus angustifolia)
Black walnut (Juglans nigra)
Eastern white pine (Pinus strobus)
Red oak (Quercus rubra)
Sugar maple (Acer saccharum)
White ash (Fraxinus americana)
Long term: >30 years
Bamboo (Phyllostachys spp.)
Wood, edible shoots
(author's observation)
Black walnut (Juglans nigra)
Ginseng (Panax quinquefolium)
Apsley ; Carroll
Agroforest Syst (2007) 71:185–193
There are several nurse crops recommended for
(Brooks Boes ), though alfalfa (Medica-
black walnut growers which are planted at time of
go sativa L.) is not (MacDaniels and Pinnow
stand establishment, then harvested or killed in the
It may benefit black walnut trees to grow Kentucky
medium term. Autumn olive (Elaeagnus umbellata
blue grass and clover in the earlier part of the
Thunb.), Russian olive (Elaeagnus angustifolia L.),
medium term, before the shade becomes too dense
European alder (Alnus glutinosa (L.) Gaertn.), and
to permit profitable growth.
black locust (Robinia pseudoacacia L.) are nitrogenfixers, and eastern white pine (Pinus strobus L.), redoak (Quercus rubra L.), white ash (Fraxinus amer-icana L.), and sugar maple (Acer saccharum Marsh.)
are grown for their wood (Burde ). An Illinoisstudy found that autumn olive and black locust both
Reports of valuable companion crops for mature
improve black walnut growth, which is attributed to
walnut stands are scarce. A walnut plantation is shady
their role as nitrogen fixers (Ponder et al.
and allelopathic after 30 years. A well-developed
There are also reports that autumn olive may reduce
stand of walnut trees will have long straight trunks
leaf spot and anthracnose (Kessler ) because
and a closed canopy 20–30 feet above the ground.
associated microarthropods consume the leaf litter
Viable understory flora must tolerate shade and
carrying the disease (Kessler Autumn olive is
juglone. The late leafing-out date of black walnut,
shorter than black walnut; it prevents deer from
combined with the early leaf-drop that may be
damaging walnut trunks without over topping and
triggered by anthracnose diseases, can create sunny
competing for sunlight. Black locust quickly grows
periods in spring and fall (Woeste and Beineke
tall, potentially competing with black walnut trees via
which suggests that spring ephemerals and late-
shading. Black locust can be cropped for bolewood
ripening fruits might play a useful role in the long
and the resultant nitrogen release in the root zone
term. Other productive species might find the summer
could benefit adolescent Walnut trees, whereas
shade useful, such as mushrooms or livestock, though
autumn olive would die off due to shade in the
the scarcity of literature suggest that most growers
medium term and release N without providing a wood
are going to be prepared to sell the wood once the
crop. The nurse crops grown for wood help develop
black walnut stand has reached maturity.
straight walnut stems, and in the case of European
There is scarce scientific literature on the subject
alder, can over-top the walnut trees before dying of
of full-shade cropping systems under black walnut.
juglone toxicity (Rietveld et al. ). A similar story
The presence of black walnut has been called ‘‘a good
is apparently the case for the fast-growing, but
indicator.of productive sites'' for growing American
juglone-intolerant eastern white pine (Fisher )
ginseng (Panax quinquefolium L.) (Apsley ;
and sugar maple (De Scisciolo et al. ).
Carroll Shiitake (Lentinula edodes Berk.) and
Growing forage for livestock may be one of the
Oyster (Pleurotus spp.) mushroom operations require
most profitable uses of walnut plantation land in the
shady environments such as the mature walnut grove
medium term. It is common in extension bulletins
can provide, but there are no specific reports of
to report that grasses such as Kentucky blue grass
culinary mushroom interactions with juglone. Forest
(Poa pratensis L.) and tall fescue (Festuca arun-
yields such as mushroom logs and pawpaw (Asimina
dinacea Schreb.) grow well under black walnut
triloba) may require shade to stay moist in the
(Funt and Martin ). A comparison of the
summer, but pawpaw is more productive when
heights of black walnut trees in the lower midwest
mature trees receive full sun. Similarly, temperate
found that 26 year-old black walnut trees growing
bamboo (Phyllostachys sp.) has been observed
with Kentucky blue grass had a site index 5 m
growing under the high crown of mature black
greater than trees growing within tall fescue fields
walnuts in Urbana, IL, though it seems to grow tallest
(Ares and Brauer ). There is also potential for
in the sunny edges. Phyllostachys can provide trellis
leguminous forage production: red clover (Trifolium
material, edible shoots, and even a ‘‘wood'' crop in
pratense L.) and white clover (Trifolium repens L.)
sunny positions, but its slow growth and sun
appear to be compatible with black walnut trees
requirements may disqualify it from long term walnut
Agroforest Syst (2007) 71:185–193
polyculture. There is no mention of bamboo in the
to be the least inhibitory of six species of wood chips
black walnut literature.
tested for allelochemical response (Rathinasabapathi
Livestock operations may make use of the walnut
stand as a source of shade for their animals, but there
Black walnut is not universally detrimental to
is no known benefit to the walnut trees. The
other cropping systems. Soil type and moisture
application of poultry litter to a 35 year old stand
regime have been implicated in differential juglone
of black walnuts in Missouri failed to produce
toxicity levels detected in soils (Fisher Zitzer
significant differences in nut yield or diameter growth
and Dawson For some species black walnut
(Ponder et al. Furthermore, the livestock will
may function as a friend rather than foe due to
require food that can only be grown in sunny
reduced competition with susceptible species (Brooks
locations. The shortage of literature on long-term
). Earthworms may be scarce under black walnut
black walnut polyculture suggests that the value of a
(MacDaniels and Pinnow ) but arthropods may
mature black walnut stand is enough for most
be more abundant and diverse (Summers and Lus-
growers without additional yields.
senhop ). Elevated soil pH (Brooks ) andsoil organic matter levels under black walnut havebeen attributed to the retardation of decay organisms
(Summers and Lussenhop It could be thatsome plants take up juglone from the soil (Thijs et al.
A forester with the singular objective of producing
) and could thus function as ‘‘buffer'' species for
black walnut wood as fast as possible will find that
intensively planting trees in protective plastic tubes,
This assessment suggests the need to de-stigmatize
applying herbicide to understory vegetation, and
juglone and recast it as a resource in need of
applying chemical fertilizers in the rows during stand
management. Just like shade, low pH soil, or a dry
establishment is the quickest route (Bendfeldt et al.
moisture regime, juglone will favor certain species
; Ponder and Jones Cutter et al. ). But
and disadvantage others. The prospect of growing
the highest intensity route also carries the highest
black walnut polycultures in the short and medium
input cost, by ruling out opportunities for multi-
term, merits further research. The logic of short-term
cropping or providing comparable functions with
gains is a major argument against tree crops in the
flora such as nitrogen fixing nurse crops.
midwest, and the potential for multiple yields in an
Black walnut could be re-cast as an ecological
ecosystem mimicking polyculture could become its
resource if its beneficial interactions were empha-
counterargument. Research in the long term
sized as often as its detrimental interactions. Black
(>30 years) is especially sparse in terms of polycul-
walnut's allelopathic chemical juglone is lethal to
tural alternatives, likely owing to the practice of
some popular flora, but the remainder of the plant
fastest-possible returns: selling the black walnut stand
kingdom may effectively receive a selective advan-
once sufficient stem diameter is achieved. For black
tage due reduced competition when grown with black
walnuts to become an investment that people protect
walnut. Additionally, black walnut is not likely to
as carefully as their retirement funds, a new gener-
attract insect pests, as the leaves have been observed
ation of research and production based on compati-
to be amongst the least popular for forest insect pests
bility and diversity may be required.
(Shields et al. which holds consistent with
The negative reputation of walnut allelopathy
their reputation as folk insect repellant (Walker
dates back to ancient Greece (Willis ). The
). Though black walnut trees can inhibit some
discovery of juglone in the 20th century, and its
plants from growing, it has never been demonstrated
identification as a causal agent in black walnut
to ‘‘ruin the soil'' as is often rumored, and to the
allelopathy, helped frame an era of research in which
contrary it appears that soil processes such as
the toxic effects were put in focus. Since 1980, there
nitrification occur unfettered in the soil with juglone
have been several papers reporting successful poly-
(Thevathasan et al. ). Black walnut wood chip
culture production methods with black walnut,
mulch is often suspected to be antagonistic to plant
including mixed stands, alley-cropping and silvopas-
growth, but a recent study found black walnut chips
ture. There now exists a lengthy list of companion
Agroforest Syst (2007) 71:185–193
species that may be grown with black walnut stands,
Davis EF (1928) The toxic principle of Juglans nigra as
adding value to the system by making use of its
identified with synthetic juglone and its toxic effects ontomato and alfalfa plants. Am J Bot 15:620
unique conditions. Though there is not a single
Dawson JO, Knowlton S, Sun SH (1981) The effect of juglone
agroforestry system for black walnut growing, a
concentration on the growth of Frankia in vitro. U.S.D.A.
collection of species compatible with black walnut
For. Serv. Res. Rep No. 81-2
gives good reason to rethink the reputation of this
De Scisciolo B, Leopold DJ, Walton DC (1990) Seasonal
patterns of juglone in soil beneath Juglans nigra (black
important tree, and ask whether the juglone could not
walnut) and influence of J. nigra on understory vegeta-
be re-cast as a resource. Our findings suggest that it
tion. J Chem Ecol 16:1111–1130
can, and that there may be multiple benefits for
Fisher RF (1978) Juglone inhibits pine growth under certain
growers who choose to do so.
moisture regimes. Soil Sci Soc Am J 42:801–803
Fuchs L (1995) Making peace with black walnuts. Am horticult
Funt RC, Martin J (1993) Black walnut toxicity to plants,
humans and horses. Ohio State University extension factsheet HYG-1148-93
Anonymous (1998) Black walnut toxicity. In: Green tips.
Gordon JH (1981) Persimmons under black walnuts. Pomona
Department of Horticulture, Michigan State University
Hejl AM, Einhellig FA, Rasmussen JA (1993) Effects of jug-
Apsley D (2004) Growing American ginseng in Ohio:
lone on growth, photosynthesis, and respiration. J Chem
selecting a site. Ohio State University extension fact
Ecol 19:559–568
Hejl AM, Koster KL (2004) Juglone disrupts root plasma
Ares A, Brauer D (2004) Growth and nut production of black
membrane H(+)ATPase activity and impairs water uptake,
walnut in relation to site, tree type and stand conditions in
root respiration, and growth in soybean (Glycine max) and
south-central United States. Agrofor Syst 63:83–90
corn (Zea mays). J Chem Ecol 30:453–471
Baughman MJ, Vogt C (2002) Growing Black Walnut.
Jose S, Gillespie AR (1996) Assessing the synergistic and
University of Minnesota Extension publication. FO-00505
competitive interactions in alley cropping: lessons from
Beineke WF (1985) Black walnut plantation management.
temperate systems involving fine hardwoods and corn. In:
Purdue Cooperative Extension publication, FNR 119
Kohli RK, Arya KS, Atul K (eds) Resource inventory
Bendfeldt ES, Feldhake CM, Burger JA (2001) Establishing
proceedings fo the IUFRO-DNAES international meeting,
trees in an Appilachian silvopasture: response to shelters,
Chandigarh, India. HKT Publications, Chandigarth, India,
grass control, mulch, and fertilization. Agrofor Syst
Jose S, Gillespie AR (1998a) Allelopathy in black walnut
Bertin C, Yang X, Weston LA (2003) The role of root exudates
(Juglans nigra L.) alley cropping. I. Spatio-temporal
and allelochemicals in the rhizosphere. Plant Soil 256:
variation in soil juglone in a black walnut-corn (Zea mays
L.) alley cropping system in the midwestern USA. Plant
Boes TK (1986) Allelopathy: chemical interaction between
Soil 203:191–197
plants. Amer Nurseryman 163:67–72
Jose S, Gillespie AR (1998b) Allelopathy in black walnut
Bohanek JR, Groninger JW (2005) Productivity of European
(Juglans nigra L.) alley cropping. II. Effects of juglone on
black alder (Alnus glutinosa) interplanted with black
hydroponically grown corn (Zea mays L.) and soybean
walnut (Juglans nigra) in Illinois, USA. Agrofor Syst
(Glycine max L. Merr.) growth and physiology. Plant Soil
Brooks MG (1951) Effect of black walnut trees and their
Kallenbach RL, Kerley MS, Bishop-Hurley GJ (2006) Cumu-
products on other vegetation. West Virginia Agric Exp
lative forage production, forage quality and livestock
Station Bull 347:341–337
performance from an annual ryegrass and cereal rye
Buergler AL, Fike JH, Burger JA, Feldhake CR, McKenna JA,
mixture in a pine-walnut silvopasture. Agrofor Syst
Teutsch CD (2005) Botanical composition and forage
production in an emulated silvopasture. Agron J 97:1141–
Kessler KJ (1988) Companion planting of black walnut with
autumn olive to control walnut anthracnose. Phytopath
Burde EL (1989) Walnut Notes. USDA For Serv North Central
Kessler KJ (1990) Destruction of Gnomonia leptostyla peri-
Carroll C (2004) Growing American ginseng in Ohio: an
thecia on Juglans nigra leaves by microarthropods asso-
introduction. Ohio State University extension fact sheet
ciated with Elaeagnus umbellata litter. Mycologia
Crist CR, Sherf AF (1973) Walnut wilt. Cornell University,
MacDaniels LH, Pinnow DL (1976) Walnut toxicity, an un-
Horticulture Extension Bulletin, Ithaca, NY
solved problem. Northern Nut Growers Association An-
Cutter BE, Coggeshall MV, Phelps JE, Stokke DD (2004)
nual Report 67:114–122
Impacts of forest management activities on selected
Matta Z, Chambers E, Naughton G (2005) Consumer and
hardwood wood quality attributes: a review. Wood Fiber
descriptive sensory analysis of black walnut syrup. J Food
Agroforest Syst (2007) 71:185–193
Meador DB, McDaniel JC, Doll CC, Shurtleff MC, Randell R
Ross M (1996) Walnuts: a mixed blessing. Flower Garden
(1986) Nut growing in Illinois. (Rev. ed. 1996) University
of Illinois Extension Circular 1102
Schmidt SK (1988) Degradation of juglone by soil bacteria.
Mollison B (1988) Permaculture: a designers' manual. Tagari,
J Chem Ecol 14:1561–1571
Tyalgum Australia
Schneiderhan FJ (1927) The black walnut (Juglans nigra L.) as
Orton CR, Jenny G (1948) Research powers of the farm. West
a cause of the death of apple trees. Phytopath 17:529–540
Virginia Agric Exp Station Bull 334:3–35
Segura-Aguilar J, Hakman I, Rydstrom J (1992) The effect of
Piedrahita O (1984) Black walnut toxicity. Factsheet. Ministry
5OH-1,4-napthoquinone on Norway spruce seeds during
of Agriculture and Food. Ontario (84-050):1–2
germination. Plant Physiol 100:1955–1961
Ponder F, Schlesinger RC, Funk DT (1980) Autumn olive
Shields VDC, Broomell BP, Salako JOB (2003) Host selection
stimulates growth of black walnut. South Lumberman
and acceptability of selected tree species by gypsy moth
larvae, Lymantria dispar (L.). Ann Entomol Soc Am
Ponder F, Jones JE (2001) Annual applications of N, P, and K
interrupt alternate-year nut crops in black walnut. J Plant
Summers DA, Lussenhop J (1976) The response of soil
Nutr 24:661–670
arthropods to canopies of black walnut. Pedobiologia
Ponder F, Jones JE, Mueller R (2005) Using poultry litter in
black walnut nutrient management. J Plant Nutr 28:1355–
Thevathasan NV, Gordon AM, Voroney RP (1999) Juglone
(5-hydroxy-1,4 napthoquinone) and soil nitrogen trans-
Radix P, Seigle-Murandi F, Benoit-Guyot JL, Kruibok S
formation interactions under a walnut plantation in
(1992) Toxicity of walnut husk-washing waters. Water
southern Ontario, Canada. Agrofor Syst 44:151–162
Res 26:1503–1506
Thijs H, Shann JR, Weidenhamer JD (1994) The effect of
Rathinasabapathi B, Ferguson J, Gal M (2005) Evaluation of
phytotoxins on competitive outcome in a model system.
allelopathic potential of wood chips for weed supression
Ecology 75:1959–1964
in horticultural production systems. Hort Sci 40:711–713
Thomsen MEM, Davis EG, Rush BR (2000) Black walnut
Reid W, Coggeshall MV, Hunt KL (2004) Cultivar evaluation
induced laminitis. Vet Hum Toxicol 42:8–11
and development for black walnut orchards. In: Michler
Walker LC (1990) Forests: a naturalist's guide to trees and
CH, Pijut PM, Van Sambeek J, Coggeshall M, Seifert J
forest ecology. John Wiley & Sons, New York
et al (eds) Black walnut in a new century, proceedings of
Willis RJ (2000) Juglans spp., juglone and allelopathy. Alle-
the 6th Walnut Research Symposium. U.S.D.A. For. Serv.
lopathy J 7:1–55
Gen. Tech. Rep. NC-243, pp 18–24
Woeste KE, Beinke WF (2001) An efficient method for eval-
Rietveld WJ (1981) The significance of allelopathy in black
uating black walnut for resistance to walnut anthracnose
walnut cultural systems. Northern Nut Growers' Associ-
in field plots and the identification of resistant genotypes.
ation Annual Report 72:117–134
Plant Breed 120:454–456
Rietveld WJ, Schlesinger RC, Kessler KJ (1983) Allelopathic
Zitzer SF, Dawson JO (1989) Seasonal changes in nodule
effects of black walnut on European black alder coplanted
nitrogenase activity of Alnus glutinosa and Eleagnus
as a nurse species. J Chem Ecol 9:1119–1133
angustifolia. Tree Physiol 5:185–194
Rink G (1985) Black Walnut: an American Wood. U.S.D.A.
For. Serv., FS-270
Source: http://willsull.net/resources/Sullivan-papers/ScottSullivanBlackwalnut.pdf
APMIS 115: 778–83, 2007 C 2007 The Authors Printed in Denmark . All rights reserved Journal Compilation C 2007 APMIS ISSN 0903-4641 Extreme neutrophil granulocytosis in a patient with anaplastic large cell lymphoma of T-cell lineage Case report FREDERIK NEESS ENGSIG,1 MICHAEL BOE MØLLER,2 HANS K. HASSELBALCH,3
Spam Classification Documentation What is SPAM? "Unsolicited, unwanted email that was sent indiscriminately, directly or indirectly, by a senderhaving no current relationship with the recipient."Objective: 1. Develop an algorithm apart from Bayesian probabilities,i.e through Frequent item set Mining, Support Vector Machines (SVM).