Curtis Rainbolt EREC-Belle Glade Weeds Commonly Found in Sugarcane.
-
Upload
jewel-adams -
Category
Documents
-
view
218 -
download
2
Transcript of Curtis Rainbolt EREC-Belle Glade Weeds Commonly Found in Sugarcane.
What Are Weeds?
➔Plant out place➔ Using this definition, almost any plant can be a
weed➔ Melaleuca--native tree in Australia, but weed in south
Florida➔ Corn--crop when it is planted, but weed when
volunteer plants come up the next year➔ Most “weeds” are non-cultivated native or non-native
plants
Why Weed ID?
➔Weeds are prominent pests in crops➔ Control methods almost always required
➔ Mechanical➔ Cultural➔ Chemical (herbicides)
➔Also important pests of natural areas➔ Invasive weeds
➔ Brazilian pepper, old world climbing fern, Australian pine, etc.
Impact of Weeds
➔Economic➔ Reduced yields of crops➔ Reduced quality of turf
➔Ecosystems➔ Crowd out native species➔ Reduced habitat quality for all species
➔ Both plants and animals
Vegetative parts of grasses often used to aid in identification:➔ 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
Diagnostic Grass Structure
➔ Primary leaf structures used to ID grass
➔ ligule➔ auricle➔ collar➔ sheath
Steps 1 to Grass ID
• Overall characteristics– Relative length and
width of first leaf– Seed characteristics
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
Differences between grasses and sedges:• Sedges have a solid, triangular in cross
section, stem. Leaves are arranged in threes (extend in three directions).
• Grass stems may be round or flattened.
Purple vs Yellow NutsedgeLeaf Characteristics
• Purple– A - boat shaped tip– B - without constriction at tip– C - midrib groove continues to
leaf tip
• Yellow– D - sharp or needle like tip– E - Constriction 1/2 to 1 1/2
inches from tip– F - Midrib groove absent or
barely visible beyond constriction point (E)
Vegetative parts of broadleaf weeds often used to aid in identification:
• cotyledons - seed leaves
• first true leaf
• older leaves
• midvein
• leaf apex
• margin
• terminal bud
Dicots: Broadleaved plants
– 1. Two cotyledons
– 2. Primary root often persists to become a strong tap root with smaller secondary roots.
– 3. Leaves are usually net veined and are usually broad at the base with a petiole or stalk usually present
Steps 3 & 4 in Broadleaf ID
• Leaf shape
• Leaf arrangement– opposite– alternate– whorled
• Root system
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
Wild oats (Sorghum almum)
• Not really an oat– Closely related to johnsongrass
• No rhizomes• Large, membranous ligule• Robust plant
– Can look like sugarcane seedling when small– Do we identify it correctly early?
Broadleaf panicum
• Panicum adspersum (Urochloa adspersa)– Relatively prostrate growth
• Wide leaves with wavy margins• Round stems• Usually dark green in color• Very similar to alexandergrass
Alexandergrass (Brachiaria plantaginea)
– Relatively prostrate growth• Somewhat wide leaves with straight margins• Round stems• Usually light green in color• Very similar to broadleaf panicum
– leaves narrower (usually)– margins straight rather than wavy (usually)
Guineagrass (Panicum maximum)
• Very problematic if you have it– Small plants have narrow leaves
• Stems, sometimes leaves very hairy
– Becomes very large– Highly branched seedhead– Round stem– Can look similar to Sorghum almum
• Sorhum almum shouldn’t be hairy
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
Bermudagrass (Cynodon dactylon)
• Very common – Easy to identify
• Small leaves• Rhizomes and stolons• Matt forming• Ligule fringe of short hairs (hard to see)
Goosegrass (Elusine 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
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.
Spiny pigweed (Amaranthus spinosus)
• Most common pigweed species– Stickerweed
• Large, upright growth habit, entire leaves
• Very evident spines located at nodes
Alligatorweed (Alternanthera philoxeroides)
• Common in many areas of the EAA– Prefers wet areas– Often spread by cultivation– Low growing
• Hollow stems when growing in wet spots• Opposite leaves• Small white blooms
Common lambsquarters (Chenopodium album)
• Common some years– Usually during the cooler months (Dec, Jan)– Can be difficult to control
• Waxy leaf surface– Small “dots” of wax are useful for ID– Gives leaves a white-gray color
• Alternate leaves• Medium size lobes on leaves
Common purslane(Portulaca oleracea)
• Very common– Probably not competitive– Prostrate growing– Succulent– Leaves small, smooth, opposite or alternate– Small, yellow flowers– Red stems
Common ragweed(Ambrosia artemisiifolia)
• Often found on ditch banks and field edges– Deeply dissected leaves– Many hairs on upper and lower surfaces– Long seedhead at top of plant
• Yellow flowers
– Similar in appearance to ragweed parthenium• Different flower type
Ragweed parthenium(Parthenium hysterophorus)
• Primarily ditchbanks– Less common than common ragweed– Leaves less deeply dissected
• Divisions don’t go all the way to the stem
– White flowers• Single, not multiples
Dayflower (Commelina spp.)
• Common in open areas, field edges– Small, probably not competitive– Prostrate growth habit– Parallel veins on leaves
• Actually a monocot, not a dicot
– Blue flowers
American black nightshade(Solanum americanum)
• Occasional weed in EAA– Problematic in vegetables (tomato, pepper)
• Same family (Solanaceae)• Resistant to paraquat in some areas
– Alternate leaves• Usually entire to somewhat lobed
– Purple fruit– Seems quite competitive
Sources of Weed ID Information
• Picture books:– Wildflower books
• Good for plants with prominent flowers
– Area-specific books• Many exist
– Varying quality of information
– Southern Weed Science Society ID Guide• Excellent resource
– Very thorough (almost to many plants)
Sources of Weed ID Information
– “Simple” keys– Many for specific crops or areas
– Helpful in crops where common weeds are limited– Not so helpful in natural/disturbed areas
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
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!
So You’re Stumped!• If you need help:
– Actual plants are best• Store in plastic bag with damp paper towel
– 8-10 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
So You’re Stumped!
• 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
So You’re Stumped!
• 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