Allelopathy of Leafy Spurge (Euphorbia esula)

Abstract

The allelopathic potential of leafy spurge (Euphorbia esulaL.) was investigated in the field and greenhouse. Reductions in frequency and density of quackgrass [Agropyron repens(L.) Beauv.] and common ragweed (Ambrosia artemisiifoliaL.) were noted where leafy spurge had high densities in the field. Field soil samples taken from areas of moderate and high leafy spurge densities inhibited tomatoes (Lycopersicon esculentumMill.) in the greenhouse. Growth of seedlings was inhibited up to 60% when leafy spurge leaves, roots, or litter were incorporated into soil, but surface applied leafy spurge litter had no effect. Growth inhibition was demonstrated for crabgrass [Digitaria sanguinalis(L.) Scop.] and tomato when 0.1 to 1.0% (w/w) of leafy spurge leaves or roots were added to soil. Based on these studies we postulate that leafy spurge exhibits allelopathic characteristics which may result from the incorporation of dead or decaying plant material in soil.