Machinery that chops and cuts herbaceous and woody plant materials and organic sediments and allows them to sink to the bottom, or facilitates the harvest of floating debris.

Considerations:

(Refer to floating island and tussocks to understand origin and impacts.)

Water uses and functions

• Applied when other control methods are not feasible or when expedited control is required
  • Control floating masses of peat, or muck that cannot be controlled with herbicides
  • Control floating islands or tussocks in emergency situations
• Flood control
  • Shred jams in flood control structures
  • Unplug jams in outfall canals, streams, rivers, or other conveyances
• Transportation / navigation
  • Shred plant masses or organic material jammed against bridges
  • Shred plant masses or organic material blocking established navigation channels
• Control drifting floating islands or tussocks in urgent or preemptive situations
  • Prevent potential damage to public and private property i.e. docks, bridges, etc.
  • Recreation and safety – prevent blockages to trails and public boat ramps

Fish and wildlife

• Avoid shredding during wildlife nesting or fish bedding periods if possible
• Prevent plant masses from covering valuable fish and wildlife habitat
• Non-selective – controls plants and animals that cannot escape its path

Control feasibility

• Shredding generally proceeds faster and is less expensive that harvesting
• Expenses are generally high
  • Acquisition cost of machinery
  • High maintenance
  • Operating costs – depends on plant type and suspended organic composition
    • herbaceous vs. woody plants vs. trees up to 10 inches in diameter
    • no suspended organic material to peat up to four feet thick
• Minimize adverse impacts to extent possible when shredding floating islands or tussocks
  • More difficult in emergency than urgent or preventive situations
  • Turbidity
    • Shred from interior of floating island or tussock toward outside
    • Leave edge for containment barrier
    • Allow as much shredded material to sink or decompose prior to harvesting barrier
  • Sediment accumulation
    • Shred floating islands where they arise – return organic material to point of origin
    • Shred as finely as possible to enhance decomposition
  • Try to avoid:
    • repeated shredding in same area
    • shredding on residential shoreline or public beaches
    • in canals or established navigation channels
  • Harvest floating shredded material where feasible – refer to harvesting considerations
    • Most material sinks to bottom while some remains at surface
    • Gasses build up during decomposition and may resurface organic material
    • Allowing shredded material to remain at surface as long as possible
    • Exposure to air enhances decomposition and compacts organics
    • Reshred material or harvest when vegetation grows over exposed organics
  • Push or guide floating islands to lower use or value area if possible prior to shredding

Other considerations

• Avoid shredding notches or irregular areas in fixed-in-place tussocks or floating islands
• Wind or water currents will catch edge breaking new material loose

Examples of Feasible Control:

• Emergency shredding of floating islands blocking structures or outfalls alleviated flooding in Marion Creek, and Lakes Hancock, Miccosukee, Apopka and Runnymeade
• Emergency shredding of floating tussocks prevented damage to bridges over the Withlacoochee and St Johns Rivers
• Shredding drifting islands in Orange Lake and Tsala Apopka prevented boaters from being stranded and prevented from returning to public boat ramps
• Shredding and harvesting drifting floating islands in Lakes Pierce and Apopka prevented further damage to boat docks and boat ramps
• Shredding reopened navigation channels overgrown by floating tussocks in tributary creeks of the St Johns River and Lake Lafayette
• Shredders chopped up about 1,000 acres of floating islands and tussocks to facilitate dredging operations on Lake Panasoffkee