Is Clove Oil All the Herbicide Farmers Need? Research Says 'No'

One of the most difficult parts of organic farming is, obviously, weed and pest control, as very few pesticides and herbicides are all natural. Now researchers are suggesting that herbicides that are as natural as you can get, derived straight from pure clove oil, are not good enough.

That's at least according to a new study published in the science journal HortTechnology, which details how researchers investigated the effectiveness of this organic herbicide on Vidalia sweet onion crops.

W. Carroll Johnson, III, who authored the study, explains that organic farmers are in desperate need for an effective herbicide because current popular means of natural weed control are not especially effective, and take a great deal of labor that could otherwise be reapplied to ensuring a high-yield harvest.

"Cultivation with a tine weeder and hand weeding are the primary tools currently used for weed control in organic sweet onion (Allium ceps)," the researcher explained in a statement. "However, conditions frequently arise that delay the initial cultivation; weeds that emerge during the delay are not effectively controlled by cultivation."

That's where organic herbicides including ingredients like clove oil, cinnamon oil, vinegar, and citric acid come in. Retailers claim that they can help control or at least supplement hand-weeding, ensuring that no new weeds arise.

To test the efficiency of the clove-oil derived herbicide, Johnson ran trials with sprays of various concentrations at the Vidalia Onion and Vegetable Research Center near Lyons, Georgia.

Interestingly, high concentrations of the natural herbicide proved no better at controlling weed growth than a more diluted spray. This could have in-part been because the commercial sprayer at the facility simply had difficulty maintaining a constant stream from the spray tank, which needed to be constantly shaken due to the unusual nature of this herbicide.

But even if an organic farmer takes the time to ensure his or her sprayers are functioning properly, experts do not think the difference in weed control is worth the effort.

"Given the lack of weed response and onion yields to clove oil applied in higher sprayer output volumes and the corresponding increase in clove oil cost when increasing sprayer output volume, we cannot recommend clove oil," Johnson concluded.