Weed Management in FL Sugarcane Curtis Rainbolt Everglades REC, Belle Glade, FL

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Weed Management in FL Sugarcane Curtis
RainboltEverglades REC, Belle Glade, FL
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Outline

• General sugarcane information
• Sugarcane production
• Planting
• Harvest
• Weed management
• Factors that influence management
• Chemical
• Mechanical
• Cultural

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FL Sugar

• Approximately 400,000 acres of sugarcane
• Grown by FL Crystals, US Sugar, and Sugar Cane
  Growers Cooperative of FL

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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

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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

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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

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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)

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Planting

• Propagated with vegetative cuttings
• Planted by both hand and machine
• 5 ft row spacing

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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

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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)

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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

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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

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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

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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

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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

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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

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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

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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

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Application timing
Envoke Asulox applied to 4-5 inch tall
crabgrass and fall panicum
applied 13 days later
applied 20 days later
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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

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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

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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

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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

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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

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