AbstractOpen‐top chambers were used to determine the relationships between a hexachloroethane (HC) obscurant, zinc deposition, and foliar injury of tree species indigenous to military training facilities. Eight eastern U.S. tree species were exposed four times to three exposure regimens (0x, 1x, 2x) of the obscurant, measured as Zn, during the 1990 growing season. Plots received ambient or charcoal‐filtered air for comparison purposes. Black locust (Robinia pseudoacaciaL.) and black cherry (Prunus serotinaEhrh.) were the most sensitive species, exhibiting significant (p<0.05) necrotic leaf spot, chlorotic mottle, and marginal necrosis of leaves at the 2x levels throughout the season. Defoliation was also greater (p<0.05) in exposed vs. unexposed plots. Sugar maple (Acer saccharumMarsh.) injury was different among exposure regimens (p<0.05) only near the end of the season. Sweet gum (LiquidambarstyracifluaL.), eastern white pine (Pinus strobusL.), loblolly pine (Pinus taedaL.), and Virginia pine (Pinus virginianaMill.) were asymptomatic. Charcoal filtration did not affect severity of symptoms. Zinc deposition was positively correlated (p<0.05) with most of the symptoms on black locust and black cherry. The HC obscurant in the concentrations used in this study adversely affected these spec
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