Effects of 2,4-D with and without wiper-applied glyphosate on leafy spurge (Euphorbia esula) shoot, shoot regrowth, and root biomass

Abstract

Pot studies outdoors under natural environmental conditions were conducted to determine leafy spurge biomass reduction resulting from broadcast application of 2,4-D (2,244 g ae ha^-1) with and without wiper-applied glyphosate. Glyphosate (575 g ae L^-1) was applied at 0, 33, 50, and 75% diluted concentrate with a wiper 24 hrs after 2,4-D was broadcast applied. Injury estimates and shoot biomass did not differ between plants treated with 2,4-D-only or the addition of wiper-applied glyphosate 21 days after treatment. Shoot regrowth biomass of plants treated with 2,4-D-only was approximately 560% greater compared to nontreated plants three months after treatment. Plants treated with wiper-applied glyphosate had shoot regrowth biomass of less than 10% compared to the nontreated plants 3 months after treatment. Root biomass of 2,4-D-only treated plants (160% of nontreated plants) followed a similar pattern of shoot regrowth biomass. Root biomass of plants treated with wiper-applied glyphosate exhibited approximately 50% reductions compared to nontreated plants. The concentrations of glyphosate tested reduced all vegetative metrics equally; therefore, all labeled concentrations should be effective. The results of the experiment show that broadcast-applied 2,4-D is more effective at reducing leafy spurge biomass with the addition of wiper-applied glyphosate.