Ward, Jeffery; Williams, Scott. 2011. Controlling an Invasive Shrub, Japanese Barberry (Berberis Thunbergii DC) Using Directed Heating with Propane Torches. Natural Areas Journal (Vol. 31 Issue 2, p156-162)
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 x 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 costs using propane torches for both initial and follow-up treatment was 2.5 hr/ha for every 1% pretreatment abundance (e.g., 25 hr for a 1-ha stand with 10% abundance). Because timing of initial treatments (pre-leafout vs. post-leafout) and follow-up treatment (early, mid, late) were equally effective in reducing Japanese barberry abundance and height of surviving stems, initial treatments can be completed from March-June and follow-up treatments can be completed from June-August in southern New England. For habitat restoration projects on properties where herbicide use is restricted, directed heating with propane torches provides a non-chemical alternative that can effectively control invasive Japanese barberry.
Keywords: Invasive Shrub; Mortality; Non-Chemical Control; Propane Torch
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