Weed Management Systems in Florida Sugarcane Calvin Odero TREC Seminar Series

Everglades Research & Education Center Weed Science Research (35%) Extension (65%) Crops ‒ Sugarcane ‒ Vegetables ‒ Bioenergy crops ‒ Rice ‒ Commercial sod

Everglades Agricultural Area 700,000 acres of land –Major crop - sugarcane –Other crops – vegetables, rice & sod 416,000 acres of sugarcane –78% on muck (organic) soils (Histosols) –22% on mineral (sandy) soils (Spodosols & Entisols) Source:

Muck soils Formed ~5,000 years –Decaying saw grass & marsh plants under flooded conditions High soil organic matter content –Up to 85% Soil depth –6 inches to over 4 feet

Muck soil subsidence Drainage of soils resulted in –Oxidation & mineralization of large quantities of organic N Microbial oxidation –50 to 75% of the subsidence Subsidence rates for EAA Histosols –0.13 to 1.71 inches/year In 1924 a 9ft post was driven into the bedrock at the EREC

Sugarcane taxonomy Giant grass (Poaceae) Tribe: Adropogoneae Saccharum officinarum L. Saccharum officinarum L. is –‘Noble cane’ with long, thick, heavy, juicy & sweet stalks Other species –S. barberi –S. robustum –S. sinese –S. spontaneum Commercial clones are typically 3-part hybrids

General agronomy Sugarcane is perennial that is harvested annually Planting season: mid-October to end-December The first year is referred to as plant cane and the successive years are ratoon or stubble crops Harvest season: mid-October to March/April –Plant cane (1 st year): months –1 st ratoon ≈ 11 months –2 nd ratoon until final year ≈ 10 to 11 months –Final ratoon (early harvest plow-out) ≈ 8 to 10 months Typically replanted every 3 to 5 years Planting Following fallow period ‒ Temporary rotation with different crops following final ratoon Successive ‒ Replanting several weeks after final ratoon

Furrowing for planting 3 or 5 furrows made in one pass GPS guided Furrows typically 4-6 inches deep 5 ft

Fertilizing before planting Fertilizer is Broadcasted or Banded in the furrow Custom blended fertilizer Primary nutrients applied ‒ P, K, Mg ‒ Cu, Zn, Mn, B ‒ N (mostly on sand soils)

Seed cane

Seed cane loading Whole stalk seed cane is loaded on wagons using a “Grab Loader”

2 to 6 crews depending on size of operation 30 to 120 A/day Hand planting sugarcane 8 or 9 people crews ‒ 4 droppers ‒ 4 choppers

Covering sugarcane after planting

Weed management in sugarcane Major cost associated with sugarcane production Successful weed control is essential Weeds can reduce sugarcane yields by competing –Moisture, nutrients & light Several weed species serve as alternate hosts –Disease & insect pests Weed control is most critical early in the season prior to sugarcane canopy closure over the row middles Weeds that mature and produce seed become –Source of seed bank replenishment –Source of re-infestation in subsequent years

Common weed species Grass & grass-like weeds Fall panicum * Guineagrass Goosegrass Bermudagrass * Almum sorghum Elephantgrass Yellow nutsedge * Purple nutsedge Broadleaf weeds Common lambsquarters * Amaranths * Common ragweed * Common purslane Alligatorweed Nightshades

Common lambsquaters Spiny amaranth American blacknightshade

Weedy and woody host plants of the sugarcane root weevil Odero et al J Ento Sci 48:81-89 Odero et al J Ento Sci 50:3-13 Coffee senna Spiny amaranth Common purslane Sugarcane

Fall panicum Bermudagrass

Weed control: crop rotation Crop rotation patterns will affect weed management –Leafy greens, sweet corn, snap bean, radishes, rice Fallow period has effectively been used to manage troublesome perennial weeds –Mechanical cultivation & herbicide application Flooding fallow fields also aids in weed control

Head lettuceSnap beansRiceSweet corn

Weed control: crop competition Crop competition for sunlight is important A good stand of sugarcane –Emerge rapidly & uniformly –Form a complete canopy –Shade the row middles early in the season Loss of sugarcane stools in ratoon crops –Rodent, insect, or harvest damage –Create open spaces in the cane canopy Maintaining maximum sugarcane populations throughout all production phases –Benefits weed control efforts

Fall panicum Bermudagrass

Weed control: cultivation Economical means of suppressing weed growth Sugarcane plants get the early advantage in the competition for light –Height differential must be established between cane plants and weeds Preemergence herbicides are most effective in establishing this height differential Only when the sugarcane plants are growing taller than competing weeds can mechanical cultivation be effective Cultivation when weeds are not present due to application of a herbicide or previous cultivations are not recommended Cultivation when weeds are not present can –Encourage germination of additional weed seeds –Remove the layer of herbicide present for soil-applied herbicides In ratoon crops, mechanical cultivators must –Cut through surface debris and thoroughly mix the soil –Row middles

Weed control: herbicides Useful and economical tools in sugarcane production Must be incorporated into an overall management plan to obtain their maximum benefit. Sugarcane must have the initial competitive advantage against weeds Application –Preemergence (PRE) –Postemergence (POST) –POST-directed Sprayer calibration is important before herbicide application

Weed control: herbicides Preemergence Atrazine Metribuzin Pendimethalin Postemergence 2,4-D Dicamba Ametryn Atrazine Metribuzin Asulam Halosulfuron Trifloxysulfuron Preplant/Preemergence/Fallow Glyphosate

Dissipation of oil-based pendimethalin Dissipation of water-based pendimethalin Odero & Shaner Weed Technol 28:82-88 Preemergence herbicides

Dissipation of atrazine DT days Dissipation of metribuzin DT days Odero & Shaner Weed Technol 28:

Broadleaf weeds 2,4-D, dicamba, atrazine, metribuzin, mesotrione Grasses Asulam, trifloxysulfuron, ametryn*, metribuzin* Sedges Halosulfuron Postemergence herbicides

Lumax A commercial premix of –Atrazine (110 g/L) –Mesotrione (30 g/L), –S-metolachlor (300 g/L) PRE or early POST –Control of fall panicum & other weed species

S-metolachlor PRE Mesotrione POST Control Premix 1x POST Premix 1x PRE

Non-crop areas Fernandez et al Weed Technol 29:

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