Abstract: A disc mower-conditioner having a disc cutterbar provided with transversely spaced rotatable cutter units operable to sever standing crop material by impact action and a flexible curtain extending around the perimeter of the disc cutterbar is disclosed wherein a transverse deflector panel is supported by the mower-conditioner frame between the disc cutterbar and the flexible curtain to restrict the movement of the forward transverse portion of the flexible curtain toward the cutterbar. The deflector panel is pivotally mounted for fore-and-aft movement about a generally transverse axis and has sufficient mass to resist movement of the curtain induced by an air flow created by rotation of the disc cutters. The deflector panel includes a lower curved portion to facilitate the passage of crop material therebeneath for presentation to the disc cutterbar.