Detection of F. solani (strain F19, panel (A)) and F. oxysporum (strain C1, panel (B)) in American ginseng root tissues using polymerase chain reaction (PCR). Gel lanes show the presence of PCR products from left to right: (I-P), phloem of part I; (I-X), xylem of part I; (II-PA), phloem under PDA plugs of part II; (II-P), area adjacent to PDA plugs of part II; (II-X), xylem of part II; (III-PF), phloem under Fusarium culture plug of part III; (III-P), adjacent Fusarium culture plugs of part III; (III-X), xylem of part III; (F), positive control (Fusarium spp.), (C), negative control (no DNA template), and (M), DNA ladder.