Peronospora hyoscyami f. sp. tabacina: Variabilidad de la sensibilidad a fungicidas sistémicos. III

a study under laboratory conditions was conducted during 2002-2003 and 2003-2004 tobacco crop seasons in order to determine the sensitivity of p. hyoscyami f. sp. tabacina to systemic fungicides metalaxyl, iprovalicarb, azoxystrobin and dimetomorph. in that way isolates from several tobacco growing regions in the provinces of holguín, ciego de ávila, cienfuegos, matanzas, la habana and pinar del río were collected. the floating leaf discs was utilized and it was demonstrated a moderate resistance to metalaxyl in the isolates lp0303 (dl50 = 21,27), lp0304 (dl50 = 3,57) and lp0305 (dl50 = 2,19). the rest of the isolates were sensitive to metalaxyl, while all tested isolated were sensitive to dimetomoph, iprovalicarb and azoxystrobin.