Sebastian updates integrated pest management approach; staff reports reduced herbicide use

City of Sebastian staff presented an update Tuesday on the city’s Integrated Pest Management plan, outlining how inspections, mechanical and biological methods and limited chemical applications are used to control invasive and nuisance plants in parks, ponds and stormwater canals.

The presentation matters because invasive aquatic and shoreline plants can reduce stormwater capacity, impede flow, damage infrastructure and spread into the Indian River Lagoon and other water bodies if not managed, City Engineer and Special Projects Director Karen Miller said.

Miller described the IPM cycle as “inspection, monitoring, identification, planning, implementing strategies, record keeping, and evaluating,” and said the city separates plans for parks and for stormwater conveyance. She said the program emphasizes nonchemical options first — biological controls, cultural plantings and mechanical removal — and treats with herbicide only as a last resort following product directions and EPA guidance.

Miller told the Natural Resource Board that the city created an IPM subcommittee in 2020, held two public workshops and ultimately adopted separate plans for parks and stormwater. She said staff and a contractor conduct joint inspections so identifications can be confirmed, and staff now use GIS-based work orders to map catch basins, ditches and treatment locations and record equipment, crew, time and estimated cubic yards of removed material.

"The goals of the program are to reduce the amount of pollutants entering service and groundwater, minimizing effects on native plants, animals, and habitats," Miller said.

Miller gave examples of nonchemical measures: air potato beetles and community removal events for air potato vine, native shoreline plantings and buffers (Riverview Park, Tula Pond, Garden Club Park), and mechanical cutting and dredging where appropriate. She noted the city received an urban forestry grant for invasive removal around a Highlands-area retention pond.

On chemical control, Miller said the city maintains separate approved lists for land-based and water-based herbicides, follows EPA and product instructions and logs each application by species, location and quantity. She said applications are limited by product directions and weather conditions and that contractors do not spray when winds or heavy rain make application inappropriate.

Board members asked how the city monitors contractors. Miller said staff perform spot checks, have attended contractor trainings and, in response to resident complaints, “we actually videotape them while they are applying,” adding that the contractor holds contracts with the South Florida Water Management District and works across the state.

Board member concerns included whether chemical applications occur during the wet season and whether hurricanes or storm events increase the spread of invasives. Miller said applications do occur in the wet season on a case-by-case basis but are weather-dependent and subject to time-between-application limits; she also said wet weather and interconnected stormwater conveyances can spread surface algae and other species and that resilient plants such as spatterdock may require mechanical removal.

Miller said the city’s monthly application logs show a decline in chemical herbicide use in recent years after higher use during the moratorium period that ended in 2020–2021, and staff will continue to tabulate applications to track seasonal patterns.

The presentation ended with Miller offering printed copies of both the parks and stormwater IPM plans to board members and continuing staff monitoring of contractor activity and GIS-based recordkeeping.