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Similar to Garden warfare 2013-handouts (10)
Garden warfare 2013-handouts
- 1. 3/11/2013
Out of the Wilds and Into Your Garden Warfare in the Garden
how plants protect themselves
from pests and invasions
C.M. Vadheim and T. Drake
CSUDH & Madrona Marsh Preserve
Madrona Marsh Preserve
Gardening with California Native Plants in Western L.A. County
March 2 & 5, 2013
Project SOUND – 2013 (our 9th year)
© Project SOUND © Project SOUND
Plants are primary producers
Why consider plant defenses?
Plants – and everything about them – are inherently
interesting
Understanding how plants interact with other living things
may improve your gardening
Plants and animals are more similar than we think – at least
at the cellular level Photosynthesis:
stored energy,
May suggest novel medicines, pesticides and other useful
other (biomass)
prodcucts
http://www.bostonbakesforbreastcancer.org/summer-sun-radiation-and-chemo/
http://www.glogster.com/beckeyy/food-web/g-6mp96eehhgdfvco22h8bna0
That means they are ‘food’ to many organisms
© Project SOUND © Project SOUND
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But plants aren’t merely generous benefactors After all, plants have to live too…
or faithful servants….
Capturing energy needed for life
(photosynthesis)
Obtaining water: roots
Obtaining nutrient chemicals
(primarily through the roots)
Reproducing: seed or vegetative
Protecting themselves from
anything that impacts the above:
Abiotic factors: temperature,
weather, soils etc.
Biotic factors: living things
http://thebillfold.com/2012/04/reader-mail-how-to-be-a-generous-person/
CA Goldenrod - Solidago californica
© Project SOUND © Project SOUND
Plants are far more Types of defenses
complex than most
Physical barriers (preformed or
of us realize induced)
Waxy cuticle
They interact with many types of
Trichomes/leaf hairs
organisms – for better or worse
Tough epidermis
They are at least as complex as Sticky gums & resins
higher animals Prickles, barbs and thorns
Dense growth habit
They were not set on this planet
Hard covering to protect seeds
for our use alone
http://img.ehowcdn.com/article-
new/ehow/images/a08/4f/it/avoid-leggy-seedling-
800x800.jpg
Etc.
They often behave more like
Defense chemicals
plant warriors than like shrinking
Preformed: always ready
violets
Induced: produced only when
needed (usually when stimulated
by an attack)
© Project SOUND © Project SOUND
http://gorillaartfare.com/character-design/two-little-kittens/
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Phytochemicals: the basis of plant chemical warfare Phytochemicals The distribution of phytochemicals within
plants is often tissue/organ specific
Phytochemicals: non-nutritive These molecules tend to be concentrated
plant metabolites that are in outer cell layers of plant organs,
essential for the survival and suggesting that they may indeed act as
proper functioning of growth and deterrents to pathogens and pests.
reproduction in plants These compounds are of two types:
Often involved in protection Constitutive chemicals: made during
against herbivores, pests and normal growth and development
micro-organisms (or other (preformed antimicrobial compounds, or
environmental stresses) “phytoanticipins”)
Sometimes used by animals that http://plantpathology.uark.edu/4844.htm
Induced chemicals: absent from healthy
eat them: plants, accumulating only in response to
pathogen attack or stress (‘phytoalexins’)
http://naturallyjodi.blogspot.com/2012/08/medical-news- As defense chemicals
2012.html#!/2012/08/medical-news-2012.html
As human plant-based medicines,
Phytochemicals are sometimes flavorings and other uses Whether a given compound has a defensive function is the
called secondary metabolites subject of much current interest & research
© Project SOUND © Project SOUND
Competition between plants: it’s a fact of life, Southern CA Walnut – Juglans californica
particularly in our mediterranean climate
Light
Water
Soil nutrients
Access to services of
beneficial organisms
Plants sometimes have to ‘fight
dirty’ to best their competitors:
allelopathy
http://primarybestsc.blogspot.com/2012/10/plants-competition.html
http://the-gist.org/2012/09/allelopathy-when-plants-attack/
http://biology.csusb.edu/PlantGuideFolder/JuglansCalif/JuglansCalifPage.htm
© Project SOUND © Project SOUND
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S. CA Walnut: not for Allelopathy: one type of chemical warfare
every yard
Term from allelon ("of each other“) and pathos ("to suffer“).
Proper location: consider Refers to the chemical inhibition of one species by another.
Size: moderate for tree
Allelopathy has generally come to mean the deleterious effect
Light: full sun/part shade
http://biology.csusb.edu/PlantGuideFolder/JuglansCalif/JuglansCalifPage.htm
that one plant has on another through the production of
Soils: clay soils best
chemical retardants
Water regime:
The "inhibitory" chemical is released into the environment where it
Tolerates seasonal flooding affects development and growth of neighboring plants.
No or very occasional deep water
in summer (hot gardens) Process is often more complex:
Allelopathy: Allelopathic plants are also capable of stimulatory effects
Leaves produce chemicals toxic The chemical producing plant may also inhibit itself with the same
to other plants chemicals that inhibit its neighbors
Can’t grow plants under walnuts The process may involve other organisms [soil microbes]
http://www.phytoimages.siu.edu/imgs/paraman1/r/Juglandaceae_Juglans_
nigra_4178.html
© Project SOUND © Project SOUND
Plants release allelochemicals in several Naphthoquinones
different ways
Often responsible for colored barks, root
barks and heartwoods
http://kremerpigments.com/shopus/index.php?cat=0104&lang=EN
Example: Juglone (C.I. Natural Brown 7)
G&product=37300&sidFEE4B14F27014E7795A5F1BD0DD62743=
Above ground 63e5300d98a56f6479a23d579380ca6a
Leaves release volatiles In leaves, roots, husks, and bark of plants in the
Juglandaceae family
Leaching from leaves
Is toxic or growth-stunting to many types of
Leaching from plant litter or
plants and insect herbivores - inhibits key
on decomposition
enzymes needed for metabolic function.
Below ground Awareness of walnut toxicity dates back at
least to Roman times
From above-ground leachates Used as:
Root exudates an herbicide
Decomposing roots a dye for cloth and inks
a coloring agent for foods and cosmetics (hair
dyes).
Folk medicine – ground/extract green hulls
http://pubs.ext.vt.edu/430/430-021/430-021.html
© Project SOUND © Project SOUND
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Juglone is an effective toxin because it affects The toxin is stored in a non-toxic form (so
basic processes required for life it doesn’t harm the walnut tree)
Juglone exists within wlanut tree cells in a
The active agent inhibiting growth of non-toxic form called hydrojuglone.
other plants was suggested by Massey
in 1925; confirmed by Davis in 1928. Hydrojuglone is colorless and generally
nontoxic, but is immediately converted to
Juglone disrupts oxygen and food use in juglone by oxidation.
both plants and animals, a respiration http://www.biologie.uni-hamburg.de/b-online/ge20/02b.gif
Upon continual contact with oxidative
poison. Juglone is like cyanide in its conditions, or tissue drying, juglone is tied
http://www.bgshoppingmall.com/Brand-Names/abbyson-
living.php
effect on people, animals, and plants up and decomposed.
Juglone is so toxic only minute amounts
When you cut open a green walnut husk, it
can sicken, sedate, or kill people and
quickly turns brown when exposed to air.
So how do walnut animals. The concentration difference This is caused by the clear, non-toxic
trees survive? of juglone between that needed for hydrojuglone being quickly converted into
sedation, and that causing death, is the toxic, dark brown juglone in the
small. presence of oxygen.
© Project SOUND © Project SOUND
Why do Juglans species make juglone? At
Allelochemicals: many modes of action least part of the story involves seedlings
Allelopathic chemicals can be Juglone in the husk protect the seed from being
present in any part of the plant - eaten. The juglone also leaches into the
leaves, flowers, roots, fruits, or surrounding soil
stems.
If juglone leaks back into a walnut root, it is
They can also be found in the quickly made non-toxic again and stored.
surrounding soil. Annual plants, garden vegetables, fruit trees, and
some broad-leaf perennials can be severely
Target species are affected by
damaged when juglone is in the soil. These are a
these toxins in many different ways: seedling’s biggest competitors
Inhibited shoot/root growth http://www.hiltonpond.org/images/WalnutBlackS Most grasses seem immune from juglone
Inhibited nutrient uptake eedling01.jpg
problems.
Altered symbiotic relationship
[mycorrhyzae] - destroying the Select mycorrhizal fungi and soil microbes have
plant's usable source of a nutrient. been shown to be highly adapted to walnut tree
control zones and the presence of juglone.
http://www.sustland.umn.edu/implement/images/trees_turf_4.gif
© Project SOUND © Project SOUND
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Other native trees/large shrubs with
allelopathic properties Dealing with allelopathy in the garden
Rake up leaves & other parts containing the chemicals(s)
Oaks – Quercus spp.
Leaves, twigs, fruit husks, and wood chips from walnut trees
Cottonwoods – Populus spp. should be well aged or completely composted before adding
Manzanitas – Arctostaphylos spp. to a garden or landscape, if at all
CA Sycamore – Platanus racemosa Walnut stumps should be ground-down or removed from a
CA Bay Laurel - Umbellularia site
californica Plant tolerant species under/near:
http://farm1.static.flickr.com/29/101896704_625b8ccece.jpg
False Indigo - Amorpha fruticosa Solanaceae, annuals are particularly susceptible
Grasses are usually not
Eucalyptus Soil microorganisms ingest allelochemicals as energy sources,
Tree of Heaven and metabolic decomposition can render the chemicals non-
toxic to plants. When soils are well drained and aerated, a
healthy population of aerobic microorganisms can accelerate
this progress.
© Project SOUND © Project SOUND
But making Juglone is expensive: is Pros/cons of preformed defense
allelopathy the only explantion? chemicals (or precursor forms of them)
Juglone precursors appear to be Positive
translocated from older tissue to
younger tissue over time. Always ready
Mechanism often involves basic
The immediate precursors of mechanisms – effective against a
juglone are found in high wide range of living things
concentrations within buds,
flowers, fruit, and in the phloem
http://enhancedbc.tfrec.wsu.edu/CA_walnut.html (vascular system). Negative
May not ever be needed – a waste of
Juglone is also effective for energy & other resources
protection from leaf, root and Not specific – so may not work as well
stem pests, like insects, diseases, against some threats
nematodes, and grazing animals.
May be deleterious to the plant itself
http://c0365781.cdn2.cloudfiles.rackspacecloud.com/datas/5598254/
http://www.graftedwalnuts.co.uk/pest.ihtml original/799px-155mmMustardGasShells.jpg
© Project SOUND © Project SOUND
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Southern Goldenrod – Solidago spectabilis var. confinis Other good native Goldenrods
http://www.jcsemple.uwaterloo.ca/goldenrod_figs.htm Solidago californica Euthamia (Solidago) occidentalis
© Project SOUND © Project SOUND
The genus Solidago: the Goldenrods Southern Goldenrod is an herbaceous perennial
~ 100 perennial species Size:
2-3 ft tall
Most grow in meadows, pastures, along
2+ ft wide, spreading
roads & ditches in North America
Unfairly blamed for hay fever in late Growth form:
summer/fall - Ragweed (Ambrosia sp.), Stout looking herbaceous
blooming at the same time but wind- perennial
pollinated, is the usual culprit. Fall/winter deciduous; dies
back to basal rosette
Easily recognized by their golden
flowering stalks with hundreds of small Foliage:
flowers; plants & flowers make nice Leaves lance-shaped – mostly
yellow & green dyes. basal
Their alternate leaves are linear to Leaves fleshy, bright to pale
CA Goldenrod - Solidago californica lanceolate. Their margins are usually green
finely to sharply serrated.
Goldenrods have been used in Roots: spreads via rhizomes
British gardens for > 200 years
© Project SOUND © Project SOUND
© 2003 Christopher L. Christie
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The genus Solidago: the Goldenrods Outside of their native range, Goldenrods
Propagation by wind- can be invasive. Why?
disseminated seed or
underground rhizomes (form
patches that are vegetative
clones of a single plant).
Goldenrod is a companion plant,
CA Goldenrod - Solidago californica
playing host to beneficial
insects, repelling some pests
Goldenrods are important
habitat plants for a wide range
of native insects, butterflies,
birds, etc.
© Project SOUND © Project SOUND
http://www.calflora.net/bloomingplants/southerngoldenrod.html
http://www.calflora.net/bloomingplants/southerngoldenrod.html
Teasing out whether the effect is due to allelopathy: Bioassays often used to test for allelopathy
can be difficult Competing processes: competition for
Light
Water
Nutrients
Associated animal species may be the
culprit:
Pollinators, mycorrhyzae, other
beneficial species
Above or below-ground pests – Solidago http://www.biosci.ohio-state.edu/~plantbio/osu_pcmb/pcmb_lab_resources/images/pcmb300lamb/allelopathyExperiment.jpg
may be tolerant
Example: testing the effects of plant tissue extracts (or specific
Vast number of chemicals produced; chemicals) on the germination of seeds.
many not toxic (at least to other plants)
Issues in relating laboratory bioassays to allelopathic
Nature of the chemicals themselves: interactions in the field; allelopathy in the laboratory is not
highly changeable (oxygen; pH; exposure always demonstrated in the field – and vice versa
to other chemicals)
http://plantecology.dbs.umt.edu/People/collaborators.html
© 2003 Christopher L. Christie © Project SOUND © Project SOUND
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Why are U.S. Goldenrods so invasive in The answer is not exactly straightforward
China? Could it be due to allelpathy?
Solidgo canadensis does influence soil
levels of possible allelochemicals
(total phenolics, total flavones and
Extracts were made from 12.5 g of dried total saponins)
leaf tissue placed in 500 ml of distilled
water. The chemical content and possible
allelopathic effects were greater in
Dilutions of each extract, ranging from S. canadensis from China than
0% to 100% in 10% increments were those from the USA as demonstrated
made. in a field survey and a common garden
experiment.
Filter paper was placed in 90 mm petri http://www.sciencedirect.com/science/article/pii/S0929139311000849
plates with 20 seeds of the target Suggests that S. canadensis has
species (lettuce & radish). But is the effect direct? evolved to be more competitive – and
possibly more allelopathic - in the
Five trials were run for each dilution for
introduced range
each goldenrod species tested.
http://posieinthevase.blogspot.com/
Allelopathy might significantly
increase competitiveness for this
© Project SOUND
invasive species. © Project SOUND
Plants have complex relationships with Roots and the rhizosphere: life within the soil
other living things
Beneficial effect
of mycorrhyzae
http://www.sciencedirect.com/science/article/pii/S1360138510001007 http://ars.els-cdn.com/content/image/1-s2.0-S1360138512000799-gr2.jpg
© Project SOUND © Project SOUND
http://www.cottoncrc.org.au/industry/Tools/Symptoms_Identification_Tool/Cotton_Symptoms/Allelopathy
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A novel, non-native plant species (like Goldenrod)
Goldenrods brought ‘novel weapons’ with them can have many effects on the environment
S. canadensis altered the indigenous
mycorrhizal fungal spore composition
and reduced the mycorrhizal
colonization of native plants one year
after invasion.
The alien Goldenrod inhibited the
colonization of native species and
changed the indigenous mycorrhizal
fungi by exuding allelochemicals.
Experimental results suggest that
http://openi.nlm.nih.gov/detailedresult.php?img=2972720_pone.0015418.g001&query=the
&fields=all&favor=none&it=none&sub=none&uniq=0&sp=none&req=4&simCollection=305
invasive S. canadensis may acquire
8081_1471-5945-11-5-6&npos=74&prt=3
spreading advantage in non-native
habitat by using “novel weapons” to
inhibit not only local plants but also
soilborne pathogens and beneficial
microbes.
© Project SOUND http://www.sciencedirect.com/science/article/pii/S016953471000145X © Project SOUND
You may have noticed that the Sunflower
family is pretty successful Possible reasons for Sunflower success
The Sunflower family Ability to adapt well to variety
(Asteraceae) is one of the of environments
most diverse families in Plasticity: changes in phenotype
California. Ability to evolve quickly – change
in the genes in the population
Largest plant family
worldwide: contains ~ 1550 Make lots of seeds
genera and 24,000 species.
Work well with wide range of
Almost 200 pages of the pollinators and other beneficial
Jepson Manual are dedicated species
http://www.wildflowers-and-weeds.com/Plant_Families/Asteraceae_pics/Asteraceae.jpg
to describing the California
?? Good defenses
species alone.
Why are they so successful?
© Project SOUND © Project SOUND
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What types of invaders/competitors do Young leaves and other tissues are
plants need to worry about? attractive food
Other plants
(compete for water,
light, nutrients)
Large herbivores
Insect herbivores
Other herbivores:
mollusks
Pathogens
Fungal
http://www.sciencedirect.com/science/article/pii/S1360138509003008
Bacterial
Viral
© Project SOUND © Project SOUND
Why do plants make the chemicals found The ‘Double-whammy’ of injury
in ‘essential oils’? http://ericwongmma.com/wp-
content/uploads/2013/01/double-
whammy.jpg Tissue damage (from physical
A wide range of reasons, many injury or herbivory)
related to communication: Vascular tissue: must seal off
quickly, then re-grow or re-attach
To attract pollinators – or the if possible
spreaders of seed (usually in
Water – Xylem tissue
flowers, fruits)
Nutrients + other - Phloem tissue
To repel herbivores – insect or
Support tissue
other; either cue or toxin
Other
http://www.tantebazar.com/gardening_histology_of_plant_part_2.php
As breakdown products from
compounds used for other purposes Secondary infection
As protection against fungi, bacteria Bacterial
and viruses
Fungal
To prevent other plants from
Viral
growing too close ?
To communicate with other plants –
via soil water or air
© Project SOUND http://ipm.ncsu.edu/corn/diseases/cornfg18.gif © Project SOUND
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Insects are known to be selective in their Certain plant compounds are effective
use of plants in the sunflower family against insect herbivores
http://ipmworld.umn.edu/chapters/charlet2.htm
Long-horned Beetle http://michellebiology.blogspot.com/2012/02/54-pesticide-and-biological-control.html
Sunflower Bud Moth
The most important of these are alkaloids, terpenoids,
steroids, phenols, saponins and tannins
This suggests that Asteraceae may selectively deter some pest species
These may be an alternative source of insect control agents
© Project SOUND © Project SOUND
The most cost effective strategy is often Mint family insecticidals: mostly terpenoids
to prevent/limit herbivory
Most common : monoterpenes (1,8-cineole,
thujone, camphor, pulegone, menthone, others)
Has a pleasant odor similar to
pennyroyal, peppermint and Plant-derived insecticides may represent
camphor. alternative pest control strategies.
They may degrade more rapidly than the
Is used in flavoring agents, in synthetic insecticides
perfumery, and in May be more specific in their action
aromatherapy Have no genotoxicity.
Pulegone
Mint oil is already used as an environmentally-
Insect repellant; less toxic to
friendly insecticide for some common pests like
animals/humans than other
wasps, hornets, ants and cockroaches
Plants in both the Sunflower insect repellants
and Mint families make a range Mints also repel some birds & other large
of chemicals to prevent/limit herbivores – terpenoid’s smells repel
herbivory
© Project SOUND © Project SOUND
http://www.safesolutionsinc.com/TweetMint_Gallon.jpg
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Diterpenes: another class of bioactive
How do plant insecticidal chemicals work?
terpenoids
Feeding deterrants:
They have 20 carbon atoms Render plants unattractive or unpalatable;
Produced by plants and fungi; often play Usually small chemicals; may be aromatic
active role as hormones (Gibberelins) Often bitter or strong tasting/smelling
Examples: alkeloids, terpenopids;
Found in resins, gummy exudates, and in
the resinous high-boiling fractions
Direct toxicity:
remaining after distillation of essential
http://ars.els-cdn.com/content/image/1-s2.0-
S0367326X02001703-gr1.gif http://www.gov.mb.ca/agriculture/crops/ins
Kill insects outright; or stun them
ects/images/fae02s00a.jpg
oils.
significantly so that they are eaten by their
Diterpenes display a broad range of predators
activities against insects Usually function as neurotoxins
Examples:
Important defense chemicals in
Asteraceae, Salvia, many others
monoterpenes Other, more subtle methods:
© Project SOUND © Project SOUND
http://www.cyberlipid.org/images/pict295.gif
How do plant insecticidal chemicals work? California/Big Gum Plant
A few more subtle means Grindelia camporum var. bracteosa
Modifying plant food absorption
Modify either the food itself, the gut wall or gut flora
Often larger size
Example: Tannins – make food undigestable
Disrupting the endocrinologic balance of insects
Affects reproduction
Acting as insect growth regulators, disrupting the normal
process of morphogenesis
May ultimately kill
Usually affects reproduction
Behaviour modifying agents
Usually influence the feeding and ovipositing (egg-laying) behavior
of insects
© Project SOUND
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Asteraceae species do much to protect
CA Gum Plant their young leaves & flowers
Erect herbaceous perennial to 4
ft tall by 4 ft wide
Grows in clay or sandy soil:
Dry stream banks, washes
Rocky fields & plains
Sandy or alkali bottomlands
Along road sides
Grows where it gets full sun
Is stress deciduous – looses
leaves during dry periods
© Project SOUND
Gumplants make an interesting array of chemicals Protecting developing leaves and flowers
Grindelia species are used as food plants
Active compounds: resin flavanoids by the larvae of some Lepidoptera species
and diterpenes of the grindelane type. including Flower Moths, other herbivores
The resin produced in multicellular Grindelane diterpenoids make up most of
glands on the surfaces of stems, the resin (to 20% of the dry weight).
leaves, and involucres - density of Grindelic acid, camporic acid,
resin glands highest on the immature 17-carboxygrindelic acid
involucre bracts and lowest on the many other diterpenoids
stems.
The diterpenoids appear to have insect
The resin is composed of grindelic repellant/insecticidal & antibiotic activity
acid and several of its derivatives.
These labdane diterpenes are similar Used as a traditional medicine (until 1960)
to the resin acids that constitute wide range of ailments: asthma, bronchitis;
Balsamic scent – fairly strong
rosin, a principal product of the naval antispasmodic , urinary tract disinfectant;
topical preparations to soothe burns, insect
stores industry
bites, skin rashes, poison ivy rash.
© Project SOUND © Project SOUND
http://www.ag.arizona.edu/~spmcl/Research/newcrops.htm
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Labdane terpinoids: typical preformed Have you ever noticed how birds know
compounds affecting a wide range of pests when the fruits are ripe?
Stored where likely to be needed
Resin ducts of trichomes of leaves
In special plastids in epidermal or other near-
surface cells
A variety of biological activities:
Antibacterial, antifungal, antiprotozoal
Found in many plant Anti-inflammatory activities and modulation of
parts (above/below- immune cell functions – may induce long-term
ground) immunity
Significant effects on basic cell processes:
Interfere with biochemical pathways of cell
death and the cell cycle phases
May explain why they affect wide range of cell
types in pests (insects, microbes) and in humans http://www.gardenguides.com/633-barren-bushes-treat-
hungry-birds.html
© Project SOUND © Project SOUND
Many fruit-berry plants use critters to Toyon/California Christmas Berry –
spread their seeds Heteromeles arbutifolia
Berries attract the critter
Critter eats the fruit –yum!
Critter moves around while
seeds pass through the
digestive tract
Seed are deposited – with
a load of fertilizer – in a
new place away from the
parent plant
Cedar Waxwing gobbling up Toyon fruits
How do the birds know the
fruits are ripe?
http://www.ibabuzz.com/garybogue/2009/04/15/cedar-waxwings-they-will-eat-no-toyon-berry-
before-its-time/ © Project SOUND
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