In the 1960s, the US military launched a program called Operation Trail Dust. A tactical maneuver against the Vietcong, the effort involved the destruction of South Vietnamese forests and farmland using so-called rainbow herbicides: Agents Green, Pink, Purple, Blue, White, and, most famously, Orange, manufactured by Monsanto and Dow Chemical. “These rainbow colors,” Thu Van Tran explains, “and the semantic treachery of their nomenclature have stained my mental space.” For her drawings from the 2012– series “Rainbow Herbicides”—four of which (all works cited, 2019) appeared in her recent show “