Light exposure affects organic weed control

Weed Science Society of America, 11/16/2012


The popularity of organic foods and products continues to climb, creating greater demand for organic agriculture. Effective natural alternatives to synthetic chemical weed and pest management are needed to meet organic standards. Essential oils, such as clove oil, offer an avenue to explore.

The journal Weed Science reports on a study of the impact of clove oil on purple sprouting broccoli and common lambsquarters. These plants were grown from seeds in greenhouse and outdoor conditions and exposed to varying concentrations of clove oil and degrees of light intensity.

Clove oil is an excellent option for organic farming because of its strong fungicidal, insecticidal, and herbicidal properties. It is available as a commercial herbicide.

In this study, the three major constituents of clove bud oil, eugenol, β-caryophyllene, and α-humulene, were examined for their individual effects on plants. Only eugenol showed a significant impact on the plants, damaging their cellular membranes.

Light intensity can also affect the efficacy of clove oil with plants. Solar intensity can create a thicker layer of epicuticular wax on leaves, acting as a protective barrier. In this study, electrolyte leakage from leaf discs sprayed with clove oil decreased as light intensity increased. Therefore, plants’ exposure to light before they are sprayed with clove oil could play a role in how well the oil controls the plants.

Read the full story, titled “Phytotoxic Activity of Clove Oil, Its Constituents, and Its Modification by Light Intensity in Broccoli and Common Lambsquarters (Chenopodium album).”




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