Weed identification and common weeds associated with sugarcane Calvin Odero Everglades REC Belle...
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Transcript of Weed identification and common weeds associated with sugarcane Calvin Odero Everglades REC Belle...
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