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8/8/2019 Weed ID Slides
http://slidepdf.com/reader/full/weed-id-slides 1/25
The first step in controlling a weed is correctidentification
C065-03
Dandelion Spiny and annual sowthistle
C062-10
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Unknown weeds cannot be properly managed
No technique controls all weed species
Not all weeds cause equal damage (thresholds)
Species respond differently to control strategies Even variants within a species (ie. herbicide resistant
biotypes)
Weed Research and Info Centerhttp://wric.ucdavis.edu
Online weed ID tool
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A number ofweed booksare available
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Several available.
I use a set by XID Services-UC Davis-WSSA-WSWS
- others
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A few online(FREE) resourcesare available
UC Davis Weed Research
and Information Centerwww.wric.ucdavis.edu
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UC Integrated Pest Management Program
http://ipm.ucdavis.edu/PMG/menu.weeds.html
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Are they terrestrialor aquatic?
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Monocot seedlings have only oneseed leaf (cotyledon) and the leaveshave parallel venation
Grasses- with or without ligules andauricles. The leaf sheaths are split andwrapped around the stem
Sedges- no ligules or auricles. The leafsheaths is continuous around the stem.The stems may be triangular in crosssection
Dicot seedlings have two seed leaves(cotyledons) and the leaves havenetted venation
Parallel venation
Netted venation
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Barnyardgrass Yellow nutsedge
Grass Sedge
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Black nightshade Annual morningglory
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What is theirlifecycyle?
Are they annual,biennial, or perennial?
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Summer annuals germinate in springand summer, produce flower and fruit
in mid- to late summer and die in thefall
Winter annuals germinate in the falland winter, flower and fruit in mid- to
late spring and die in the spring andsummer
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Filaree
Winter annual
Purslane
Summer annual
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Biennials live for two growing seasons.
Seeds germinate and overwinter as a
basal rosette with a thick storage root. The stems flower and produce seed in
the summer of the second season anddie in the fall.
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Common burdock Wild carrot
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Perennials live for more than twoyears and they may be:
Simple herbaceous- reproduce only fromseeds but if the plant is injured or cut,each piece can regenerate into a new plant
Creeping herbaceous- over-winter and
produce new vegetative structures such asrhizomes, tubers, stolons, bulbs etc.
Woody plants- have woody stems
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Dandelion
Simple herbaceous
Johnsongrass
Creeping herbaceous
Poison oak
Woody pl ant
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Look at leaves
Netted or parallel veins?
Leaf shape and margin texture Presence of hairs or other structures
Look at flowers, and fruit/seeds,if present
Look at roots
Tap root, fibrous roots, rhizomes,stolons, tubers, etc
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Look forcotyledons and
subsequent leaves– their shape,texture etc can giveyou and idea
True leaf Cotyledon
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Look for auricles andligules, shape of the
sheath, hairiness of thesheath, seed heads
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Auricle: an
appendage that
grows from theedge of the collar
and may wrap
around the stem.
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Ligule: a structure
that grows from
the collar area onthe inner side of
the leaf. Ligule
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