Many plants produce allelochemicals, which are secondary metabolites such as terpenoids, hydroxylated aromatic compounds, and phenolics. These compounds are produced through various metabolic pathways and affect the growth of other plants. Allelochemicals often act as germination or growth inhibitors for surrounding plants, providing a competitive advantage for the plant that produces them.
Various organic mulches have been identified to possess allelopathic properties, including pine bark, shredded wood chips, black walnut wood chips, red maple leaves, and shredded cypress. Previous research has identified the presence of phenolic compounds—such as catechin, quinic acid, gallic acid, protocatechuic acid, and chlorogenic acid—responsible for the allelopathic nature of eucalyptus hardwood.
Pine bark mulch, in particular, possesses allelopathic properties due to the presence of monoterpenes, pinenes, camphene, and carene. These compounds can inhibit the germination and growth of weed seeds. Therefore, allelochemicals have the potential to act as natural herbicides or biopesticides and can be used for weed management in ornamental crop production.
Using natural products instead of synthetic chemicals could be beneficial due to their ability to readily decompose, with no risk of volatilization or drift. Additionally, many allelochemicals may have different modes of action than chemical herbicides, providing alternative sites of action for weed control.
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