San Diego Gas & Electric
DRG’s Century plant eradication pilot uses chemical applications in place of costly off-cycle pruning to kill the pesky plant, which poses a safety risk to San Diego Gas & Electric distribution and transmission systems.
DRG’s Century plant eradication pilot uses chemical applications in place of costly off-cycle pruning to kill the pesky plant, which poses a safety risk to San Diego Gas & Electric distribution and transmission systems.
The Challenge
The unpredictable Century plants (Agave americana) are fast-growing plant species often used in landscaping by homeowners unaware they will someday sprout a 30-plus foot flower stalk. Often found in large clumps that flower during different annual cycles, these plants provide little warning before shooting up their end-of-life flower stalks in a matter of weeks. The implications of this are, at best, minimum clearance violations, reliability threats, and potential catastrophic wildfire ignition sources.
SDG&E currently uses a costly off-cycle inspection program, reviewing each of the estimated 24,000 known plants in their system during the spring flowering season. Spread over thousands of properties, this program accounts for tens of thousands of dollars in annual inspection costs alone. Pruning and mechanical removal of the plants is hazardous due to their caustic sap that causes chemical burns if in contact with skin.
To reduce annual spend, and improve safety, Davey Resource Group, Inc. (DRG) proposed a chemical eradication program to permanently reduce the number of century plants in SDG&E territory.
The Solution
Phase 1 of the pilot took place in September 2020. During this phase, DRG identified 272 plants in 25 locations on SDG&E-owned properties that were remote and not visible to the public. DRG sprayed the century plants with an herbicide mixture that quickly killed the plants by targeting the roots.
DRG used ResourceKeeper to document the treatment, allowing for easier follow-up inspections and county-required herbicide reporting.
The Results
Within weeks after the herbicide application, all plants were not only killed, but the natural desiccation process helped with any necessary cleanup. The once large plants that can weigh hundreds of pounds were reduced to a small pile of dried material that not only is much safer to remove, but also a fraction of the biomass of a live plant. Where possible, it is planned to leave the material on-site to provide habitat for small mammals and reptiles. DRG is preparing to take the pilot into a second phase, which is expected to take less than a month from start to finish to treat over 700 plants.
Without the necessity of regulated off-cycle inspection and follow-up pruning for these century plants, SDG&E can use the time and budget on other wildfire mitigation and reliability efforts.
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