In vitro suppression of Sclerotinia minor by a seaweed extract from Durvillaea potatorum and Ascophyllum nodosum

Abstract

Five in vitro bioassays demonstrated a capacity for an undiluted seaweed extract, made from a combination of Durvillaea potatorum and Ascophyllum nodosum, to suppress the growth of Sclerotinia minor by 18-100 %. Inundation in the seaweed extract significantly (p ≤ 0.05) suppressed growth of sclerotia by 90 %, and reduced disease severity in lettuce seedlings. A control buffered to the same pH (8.8) as the seaweed extract also significantly (p ≤ 0.05) suppressed the growth of sclerotia, but only by 22 %. This suggests that pH only partially explains the suppressive effect of the extract against S. minor, and undiscovered modes of action exist.