Japanese knotweed composting feasibility study Delaware County NY

Japanese knotweed composting feasibility study, Delaware County, NY Laurence Day, Jessica Rall — Delaware County SWCD Susan Mc. Intyre — Delaware County DPW Charles Terrance — SUNY Delhi

Managing Invasive Species (e. g. Polygonum cuspidatum) • Effect of climate change on invasives = • We need a variety of Disposal Options ?

Problem: Invasives at Stream Rehab Sites Stream Rehab & Realignments � [photo of knotweed at stream site]

Drying extricated plants for burning, during a wet summer…

Delaware County Solid Waste Composting Facility, Walton Why not compost removed knotweed? Might this compromise weed-free status of the county’s compost? Biosolids composting requires sustained temperatures ≥ 55° C for 3 consecutive days.

“Sentinel Chamber” LIVE (Compost)

Knotweed sample collection site

30 Samples each of 4 Tissue Types

Wrapped in Nylon Netting “Wontons”

Compost+Wanton+Compost+…

Filled “Knotweed Sentinel”

Four Treatment Groups + Control 1. Three sentinels buried in compost for 3 days. 2. Six sentinels buried in compost for 6 days. 3. Moist heat only, 52° - 55° C for 3 days. 4. ‘Equipment blank’ placed samples in wontons & sentinels, then into growth chamber for 6 days. 5. Control Group planted directly into growth chamber at SUNY Delhi.

Nine Sentinels Buried in Compost Two Groups: 3 -days or 6 -days 55° - 63° C, mean=61. 3° C (142° F)

Moist Heat Treatment 52° - 55° C for 3 consecutive days

Inspection and Potting

Growth Chamber, Summer Conditions 27° C “days” (lights on) 19 ° C “nights” (lights off)

100% GROWTH vs. 0% GROWTH CONTROL GROUP COMPOST-BURIED GROUP

RESULTS � Both composting (≥ 3 d at >55° C) and moist heat (≥ 3 d at 52°-55° C) effectively killed all growth of roots and crowns (P<. 01). � Root and Crown samples much more likely to sprout and grow than leaf or stem samples. � Sentinels performed well, although heat softened plastics; careful removal needed.

Conclusions � Temperatures adequate to safely compost biosolids are also appear effective on Japanese knotweed vegetation. � It appears feasible to compost knotweed at the Delaware County SWM facility, not compromising “weed-free” status of compost. � Simple, inexpensive “Sentinels” proved useful to safely assess composting feasibility for invasives.

NY Biosolids Composting Locations (26 Locations in 19 Counties)

Epilogue ↗