1. Weeds Commonly Found in Sugarcane
Curtis Rainbolt
EREC-Belle Glade

2. 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

3. 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.

4. Impact of Weeds Economic Ecosystems Reduced yields of crops
Reduced quality of turf
Ecosystems
Crowd out native species
Reduced habitat quality for all species
Both plants and animals

5. How Do Weed Cause Harm?
Competition for:
Light
Nutrients
Water
Space

6. Identification

7. 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

8. Diagnostic Grass Structure
Primary leaf structures used to ID grass
ligule
auricle
collar
sheath

9. Vegetative Characteristics
Blade
Midrib
Ligule
Collar
Sheath
Auricle

10. Auricle Variations

11. Ligule Variations

12. Sheath Variations

13. Steps 1 to Grass ID Overall characteristics
Relative length and width of first leaf
Seed characteristics

14. Step 2 to Grass ID
Stem Type
Round
Flat
Triangular

15. Step 3 to Grass ID
Ligule Type
Absent
Hairy
Membranous

16. Step 4 to Grass ID Blade Type Hairy or not (glabrous)
Midrib prominence and color
Margin characteristics
Presence of auricles

17. Step 5 to Grass ID Sheath margins Split with overlapping margins
United
Margin with hairs or not

18. Step 6 to Grass ID Root systems Perennial with creeping rhizomes
Annual

19. 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.

20. Purple vs Yellow Nutsedge Leaf Characteristics
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)

21. Purple vs Yellow Nutsedge

22. Purple vs Yellow Nutsedge

23. 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

24. 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

25. Diagnostic Broadleaf Structure
Cotyledon
Leaf
midvein
margin
shape
arrangement

26. Steps 1 & 2 in Broadleaf ID
Overall appearance
Shape of cotyledons

27. Steps 3 & 4 in Broadleaf ID Leaf shape Leaf arrangement Root system
opposite
alternate
whorled
Root system

28. Common Sugarcane Weeds

29. 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

30. Fall panicum (Panicum dichotomiflorum)

31. 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?

32. Wild Oats (Sorghum almum)

33. 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

34. Broadleaf panicum

35. 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)

36. Alexandergrass (Brachiaria plantaginea)

37. Alexandergrass vs Broadleaf panicum

38. 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

39. Guineagrass (Panicum maximum)

40. 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

41. Napiergrass (Pennisetum pupureum)

42. 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

43. Paragrass (Brachiaria mutica)

44. Bermudagrass (Cynodon dactylon)
Very common
Easy to identify
Small leaves
Rhizomes and stolons
Matt forming
Ligule fringe of short hairs (hard to see)

45. Bermudagrass (Cynodon dactylon)

46. Goosegrass (Elusine indica)
Found in many fields
Low growing
Very white, flattened stems
Looks like it has been stepped on
Probably not competitive

47. Goosegrass (Elusine indica)

48. 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

49. 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.

50. Spiny pigweed (Amaranthus spinosus)
Most common pigweed species
Stickerweed
Large, upright growth habit, entire leaves
Very evident spines located at nodes

51. Spiny pigweed (Amaranthus spinosus)

52. 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

53. Alligatorweed (Alternanthera philoxeroides)

54. 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

55. Common lambsquarters (Chenopodium album)

56. Common purslane (Portulaca oleracea)
Very common
Probably not competitive
Prostrate growing
Succulent
Leaves small, smooth, opposite or alternate
Small, yellow flowers
Red stems

57. Common purslane (Portulaca oleracea)

58. 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

59. Common ragweed (Ambrosia artemisiifolia)

60. 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

61. Ragweed parthenium (Parthenium hysterophorus)

62. 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

63. Dayflower (Commelina spp.)

64. 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

65. American black nightshade (Solanum americanum)

66. 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)

67. 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

68. Sources of Weed ID Information
Web Picture/Taxonomic Sites
Aquatic, Wetland and Invasive Plant Particulars and Photographs (U. of Florida)
Excellent pictures and information
Weed Identification and Control in Southern Turfgrasses (U. of Georgia)
Pictures, descriptions

69. 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!

70. 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

71. 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

72. 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

73. 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.)