weed identification and common weeds associated with sugarcane calvin odero everglades rec belle...
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Weed identification and common weeds associated with sugarcane
Calvin Odero
Everglades RECBelle Glade, FL
Weed classification
• Weeds come in all growth forms• May be classified as
– Grass– Grass-like (sedge)– Broadleaf
• Forbs• Succulents• Shrubs
Monocots
Dicots
Weed classification: life cycles
Annuals- reproduce by seed only Biennial:
Life cycle completed in two years Flowering and fruiting in second year Examples: wild carrot, cudweed
Perrenials: Simple- reproduce by seed only Creeping- reproduce by seed and vegetative
propagules
Grass identification: vegetative parts
• Leaf blade, blade margin• Collar margin• Midrib• Ligule - structure which
occurs in grasses at point where the leaf sheath and blade meet
• Auricle - projections where sheath and blade meet
• Sheath margins - split with overlapping margins or united
Auricle variations
Ligule variations
Sheath variations
Steps 1 to grass ID
• Overall characteristics– Relative length and
width of first leaf– Seed characteristics
Step 2 to grass ID
• Stem Type– Round– Flat– Triangular
Step 3 to grass ID
• Ligule Type– Absent– Hairy– Membranous
Step 4 to grass ID
• Blade Type– Hairy or not (glabrous)– Midrib prominence and
color– Margin characteristics– Presence of auricles
Step 5 to grass ID
• Sheath margins– Split with overlapping
margins– United– Margin with hairs or
not
Step 6 to grass ID
• Root systems– Perennial with
creeping rhizomes– Annual
Monocots: grasses and sedges
Grasses Sedges (Grass-like)
Stems • Hollow or flattened• Occasionally solid• Nodes (jointed)
• Solid• Triangular (3-sided)• Without nodes
Leaves • Parallel veins• 2 sides
• Parallel veins• 3 sides
Flowers • Small• Inconspicuous
• Small• Inconspicuous
Example • Fall panicum • Yellow nutsedge
Yellow vs purple nutsedge
• Yellow
(Cyperus esculentus)– Leaves gradually taper
to a point– Flowers yellowish-
brown– Tubers smooth, round
shaped, at ends of rhizomes
• Purple
(Cyperus rotundas)– Leaves abruptly tapers
to a point– Flowers purple to
brown– Tubers rough, irregular
shaped, connected in chains
Purple vs yellow nutsedge
Fall panicum (Panicum dichotomiflorum)
• Most common grass in the area• Relatively easy to identify
– Stem can be hairy or smooth– Hairy when young– Ligule fringe of hairs– Round stem– Widely dispersed seedhead
Fall panicum (Panicum dichotomiflorum)
Goosegrass (Eleusine indica)
• Found in many fields• Low growing
– Very white, flattened stems
– Looks like it has been stepped on
– Probably not competitive
Crabgrass (Digitaria spp.)
• Very wide first leaf
• Initial clumping growth progressing to prostrate, tillering
• Visible membranous ligule
• Can be very hairy, or hairless, depending on species
Broadleaf panicum (Urochloa adspersa)
• Relatively prostrate growth– Wide leaves with wavy
margins– Round stems– Usually dark green in
color– Very similar to
alexandergrass
Broadleaf panicum (Urochloa adspersa)
Crowfootgrass (Dactyloctenium aegyptium)
• Plants glabrous, blade margins hairy
• Seed head like a crow foot
• Bends and roots at the lower nodes
Bermudagrass (Cynodon dactylon)
• Easy to identify• Small leaves• Rhizomes and stolons• Mat forming• Ligule fringe of short hairs (hard to see)
• Produces seed and spreads vegetatively
Bermudagrass (Cynodon dactylon)
Sorghum (Sorghum almum)
• ‘Wild oat’• Closely related to
johnsongrass– No rhizomes– Large, membranous
ligule– Robust plant
Sorghum (Sorghum almum)
Torpedograss (Panicum repens L.)
• Perennial with robust, creeping, sharply pointed rhizomes
• Leaf blade stiff and erect
• Hairs on upper and lower leaf surface
• Seedheads with stiff, ascending branches
• Occurs in wet areas
Guineagrass (Panicum maximum)
• Some plants are extremely hairy, while others are hairless
• Small plants have narrow leaves
• Becomes very large• Highly branched
seedhead• Round stem
Napiergrass (Pennisetum pupureum)
• Very robust plant– Forms dense clumps
in fields– Long, wide leaves with
finely toothed margin– Up to 12 feet tall– Seedhead has “bottle
brush” appearance
Paragrass (Brachiaria mutica)
• Prostrate growing, medium size grass– Long stems covered
with hairs• Short hairs on leaf
surface
– Swollen nodes– Grows in very wet
areas• Often moves out of
ditches
– Pasture grass in Africa
Dicots: broadleaf plants
• Two cotyledons• Primary root often becomes a strong tap
root with smaller secondary roots• Leaves are usually net veined and broad
at the base with a petiole or stalk
Dicots: broadleaf plants
Forbs Shrubs Succulents
Stems • Solid• Pithy
• Solid • Growth rings
• Fleshy, thick• Sharp spines
Leaves • Net-veined • Net-veined • Small, fleshy• Seldom present
Flowers • Small or large • Colored• Showy
• Small• Showy
• Showy
Example • Common lambsquarters
• Lantana • Cacti
Broadleaf identification: vegetative parts
• Cotyledons - seed leaves
• First true leaf• Older leaves• Midvein• Leaf apex• Margin• Terminal bud
Steps 1 & 2 in broadleaf ID
• Overall appearance
• Shape of cotyledons
Steps 3 & 4 in broadleaf ID
• Leaf shape
• Leaf arrangement– opposite– alternate– whorled
• Root system
Spiny amaranth (Amaranthus spinosus)
• Most common‒ Large, upright growth
habit, entire leaves‒ Very evident spines
located at nodes
Livid amaranth (Amaranthus blitum)
• Can be prostrate or erect
• Notched leaf tips
Alligatorweed (Alternanthera philoxeroides)
• Common in wet areas of the EAA‒ Often spread by
cultivation‒ Low growing
• Hollow stems when growing in wet spots
• Opposite leaves• Small white blooms
Alligatorweed (Alternanthera philoxeroides)
Common lambsquarters (Chenopodium album)
• Common during the cooler months
• Can be difficult to control due to waxy leaf surface that leaves a white-gray color
Common purslane (Portulaca oleracea)
• Prostrate, succulent• Leaves small,
smooth, opposite or alternate
• Red stems• Small, yellow flowers
Common ragweed (Ambrosia artemisiifolia)
• Deeply dissected leaves
• Many hairs on upper and lower surfaces
• Long seedhead at top of plant
• Yellow/white flowers in multiples
Ragweed parthenium (Parthenium hysterophorus)
• Less common than common ragweed‒ Common along
canals, ditch-banks, noncrop areas
• Leaves less deeply dissected‒ Divisions don’t go all
the way to the stem
• White flowers‒ Single, not multiples
American black nightshade (Solanum americanum)
• Becoming more common in EAA‒ Alternate leaves
• Usually entire to somewhat lobed
‒ Purple fruit
Dayflower (Commelina spp.)
• Common in open areas, field edges– Small, probably not
competitive– Prostrate growth habit– Parallel veins on
leaves– Actually a monocot– Blue flowers
Sources of Weed ID Information
• Web Picture/Taxonomic Sites– Aquatic, Wetland and Invasive Plant
Particulars and Photographs (U. of Florida)• Excellent pictures and information• http://aquat1.ifas.ufl.edu/photos.html
– Weed Identification and Control in Southern Turfgrasses (U. of Georgia)
• Pictures, descriptions• http://www.griffin.peachnet.edu/cssci/TURF/turf.htm
• Southern Weed Science Society ID Guide
Sources of Weed ID Information
• Web Picture/Taxonomic Sites–Many, many more sites
• Many reputable sites– Many universities– Other public agencies
• Buyer beware– Some incorrect information on the web!
If you need help
• Actual plants are best– Store in plastic bag with damp paper towel
• 8 t0 10 hours
– Press between two pieces of paper• Change paper often while drying• Will last indefinitely
– Store on truck dashboard• PLEASE DON’T!
– Bring several plants• Flowers and seeds if possible• Different growth stages if possible
If you need help
• Pictures– Overall view (growth habit)– Specific characteristics
• Ligule (grasses)• Hair characteristics• Leaf shape• Root system
– Tubers, rhizomes, stolons
• Stem shape• Seeds or flowers if available• Other characteristics we looked at earlier
If you need help
• Additional information– What type of area
• Dry or wet• Sandy or muck• Cropped area, natural area, disturbed area• History of area (previous crops, etc)
– Actual location• County, nearby town/city/landmark
Take Home
• Weed ID can be challenging– Many resources available
• Web is very helpful
– When you need help:• Provide as much information as possible
– Quality plant sample– Identify important/unique characteristics– Site information (wet vs. dry, etc.)
Weed ID manuals
Contact Information
Calvin Odero
University of Florida-IFAS
Everglades Research & Education Center
3200 E Palm Beach Road
Belle Glade, FL 33430
561-993-1509