Allelopathic Effects of Organic Mulch for Controlling Weeds in Ornamental Production
Many plants produce allelochemicals, which are secondary metabolites
such as terpenoids, hydroxylated aromatic compounds, and phenolics that are
produced through various metabolic pathways that effect the growth of other
plants. These chemicals often act as germination or growth inhibitors for
surrounding plants, providing a competitive advantage for the plant that
produces the allelochemical. Various organic mulches have been identified that
possess allelopathic properties such as pine bark, shredded wood chips, black
walnut wood chips, red maple leaves and shredded cypress. Previous research has
identified the presence of phenolic compounds – catechin, quinic acid, gallic
acid, protocatechuic acid, and chlorogenic acid; that were responsible for allelopathic
nature of eucalyptus hardwood. Pine bark mulch possesses allelopathic
properties due to the presence of monoterpenes, pinenes, camphene, and carene
that can inhibit 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 because of their ability to readily decompose and there is no risk
of volatilization or drift. In addition, many allelochemicals may have different
modes of action than chemical herbicides, thus providing alternative sites of
action for weed control. This can help in tackling herbicide resistance issues
that are becoming ever more prevalent in weedy populations. Research conducted
at Michigan State University by Dr. Debalina Saha’s team has found that pine
bark and hardwood mulch extracts can provide excellent liverwort control in
container production within greenhouse conditions till 10 weeks. Hence, the allelopathic
potential of organic mulches can be a promising option for biopesticidal
control of weeds.
Debalina Saha
Assistant Professor, Michigan State UniversityDebalina Saha is an Assistant Professor of ornamental weed management in the Department of Horticulture at Michigan State University. She has an appointment in research, teaching, and extension. Debalina provides statewide weed identification and management recommendations for ornamental plant production in greenhouses, nurseries, landscapes, and Christmas tree production. The primary goal of her research program is to improve upon current weed control practices and develop new effective methods of weed control using an integrated approach that involves both chemical and non-chemical strategies.
