Weed Management in
FL Sugarcane
Curtis Rainbolt
Everglades REC, Belle Glade, FL
Outline
• General sugarcane information
• Sugarcane production
– Planting
– Harvest
• Weed management
– Factors that influence management
– Chemical
– Mechanical
– Cultural
FL Sugar
• Approximately
400,000 acres
of sugarcane
• Grown by FL
Crystals, US
Sugar, and
Sugar Cane
Growers
Cooperative of
FL
Sugarcane Biology
• Sugarcane is a giant perennial grass
(Poaceae)
• Tribe: Adropogoneae
• Commercial clones are typically
hybrids of Saccharum officinarum L.
and a combination of S. barberi, S.
robustum, S. sinese, and
spontaneum
Growing Season
• Planted September to December
• Grows for approximately one year
between harvests
• Harvest season runs from October
through March
• Cane that will be replanted
(successively) is harvested first
Sugarcane Growth
• Grows rapidly in the summer period
of warm temperatures and high
rainfall
• Matures, ripens, and is easily
harvested during the cool, dry
winters
• The lake provides a winter warming
effect
Soils
• About 90% is grown
on muck soils
• ~ 70 to 90%
organic matter and
do not require N
fertilizer
• Remainder is grown
on sand soils (1-3%
OM)
Planting
• Propagated with vegetative cuttings
• Planted by both hand and machine
• 5 ft row spacing
Sugarcane Harvest
• Most sugarcane in FL is burned prior
to harvest to remove leaf material
• Yields range from 20 to over 100
tons/acre
• Yields typically decrease with each
ratoon crop
• The average is around 45 tons/acre
Green Cane Harvest
• As the population of S. FL grows, air
quality becomes a larger issue
• Many sugarcane producing countries
are phasing out burning
• The impact of GCH on the FL
production system is unknown
• GCH results in a heavy residue layer
(5-15 tons/acre)
Weed Management
Overview
• Most growers utilize an integrated
approach (primarily chemical and
mechanical)
• Sugarcane is relatively competitive
and somewhat forgiving
• South FL environment is ideal for
many tropical and sub-tropical weed
species
Factors that influence
weed management
• Virtually a monoculture crop
• Row spacing
• Crop age
• Minor use crop
• High organic matter soils
• Corporate mentality (sugarcane
prices) and tradition
Monoculture
• Crop rotation is a valuable tool for
weed management
• The majority sugarcane is replanted
every 3 years
• Only a small percentage of the fields
are rotated to vegetables or left
fallow
Row spacing
• Sugarcane is planted on 5 ft rows
• Although a competitive crop, grows
slowly at temperatures below 70 F
• Results in bare ground following
planting and harvest until ~March
• Cultivars vary in their canopy
architecture
Crop Age
• Yields typically decrease each year
• Influences the crop value and the
amount growers are willing to spend
for weed control
• Additionally, some growers do not
apply herbicides to plant cane
• Weed pressure typically increases
Minor use crop
• Although a major crop in south
Florida, sugarcane is a minor use
crop in the US and worldwide
• Consequently, there are a limited
number of registered herbicides
• Little incentive for new product
research in current ag chemical
industry climate
Muck Soils
• High organic matter (70-90%) has
considerable effect on duration of
weed control with PRE herbicides
• Despite high use rates, control can
last less than 4-6 weeks
• High rates increase likelihood of crop
injury
• Results in a reluctance to use PRE
herbicides
Corporate Mentality and
Tradition
• Weed control decisions are often
made by accountants
• Results in a fixed budget and plan for
weed control
• Goal is often quantity of acres
treated rather than quality
• Traditional reliance and overuse of on
tillage
Application timing
Envoke + Asulox applied
to 4-5 inch tall crabgrass
and fall panicum
applied 13 days later
applied 20 days later
Chemical Weed Control
• Both PRE and POST herbicides are
used
• PRE treatments are typically POST to
the crop
• Most herbicide applications are
banded over the row
• Mainly older chemistries
• Short residual with PRE herbicides
PRE herbicides
• Atrazine is the backbone of most
weed control programs
– Used both PRE and POST
– Applied at 3-4 lbs per acre, and 1 to 2
times per season
– Typically last 3-5 weeks
• Heavy reliance on triazine herbicides
POST Herbicides
• Asulam is used extensively for grass
weed control
• Because of cost it is often applied
late to insure only 1 application
before canopy closure
• Trifloxysulfuron, halosulfuron for
nutsedge control
• 2,4-D for broadleaf weed control
Mechanical Weed Control
• Varies depending on plant cane or
ratoon cane
• Plant cane-scratchers are used over
the top of the cane and tines are
removed as the can gets larger
• Ratoon cane-disk cultivators are used
for weed control in row middles
Cultural Weed Control
• Selection of cultivars that have quick
canopy closure
• Seed cane from clean fields
• Control of weeds on field borders and
ditch banks