Submitted to: Weed Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/20/2006
Publication Date: 7/20/2006
Citation: Boyd, N., Brennan, E.B. 2006. Burning Nettle, Common Purslane, and Rye Response to a Clove Oil Herbicide. Weed Technology. 20:646-650. Interpretive Summary: Few herbicides are approved for use in certified organic production systems. Weed management in organic vegetable production systems can be difficult and expensive because it may require extensive cultivation and hand weeding. Clove oil is an essential oil that functions as a contact herbicide that may provide an additional weed management tool on organic farms. This study evaluated the effect of clove oil and various concentrations and spray volumes on burning nettle, purselane and rye. Rye was not effectively controlled by clove oil. Clove oil controlled broadleaf weeds at high concentrations but its cost makes use prohibitive even in high value vegetable production systems.
Technical Abstract: Weed management is often difficult and expensive in organic production systems. Clove oil is an essential oil that functions as a contact herbicide that may provide an additional weed management tool on organic farms. Burning nettle, purslane and rye responses to a clove oil mixture applied at spray volumes of 281 L/ha (with clove oil concentrations of 6.4, 12.8, 25.6, 51.2 and 102.4 L a.i./ha) and 468 L/ha (with clove oil concentrations of 10.7, 21.3, 42.6, 85.3 and 170.6 L a.i./ha) were examined. Log-logistic curves were fitted to the nettle and purslane data to determine the dose required to reduce weed dry weight by 50 (GR50) and 90% (GR90). A three parameter Gaussian curve was fitted to the rye data. The GR50 and GR90 were largely unaffected by spray volume. Nettle dry weight was reduced by 90% with 12 to 61 L clove oil/ha whereas 21 to 38 L clove oil/ha were required to reduce purslane biomass to the same level. Rye was not effectively controlled by clove oil. Clove oil controls broadleaf weeds at high concentrations but its cost makes use prohibitive even in high value vegetable production systems.