Controlling an Invasive Shrub, Japanese Barberry (Berberis thunbergiiDC), using Directed Heating with Propane Torches

Abstract

ABSTRACT: Japanese barberry (Berberis thunbergii DC) is a non-native shrub currently found in 31 states and four Canadian provinces. We examined the effectiveness of directed heating using 400,000 BTU backpack propane torches to control Japanese barberry infestations at two study areas in southern Connecticut. Each study area had eight 50-m × 50-m plots. Treatment combinations included a pre-leafout or post-leafout initial treatment with propane torches to reduce the size of established clumps and an early (late June), mid (early July), or late (late July) follow-up treatment to kill sprouts that developed from surviving root crowns. All treatment combinations were equally effective and reduced barberry abundance (a surrogate for cover) from 31% prior to treatment to only 0.5% the following autumn (i.e., a 98% reduction). All treatment combinations were also equally effective in reducing the size of surviving barberry to an average of only 11 cm compared with 74 cm for untreated clumps. Estimated labor co...