Pesticides, herbicides, chemicals and toxins all seem to be the primary way for dealing with weeds. Unfortunately, or fortunately for families going the organic route many of these if not all of these options are not suitable for organic farming.
So what does this mean for the organic farmer? It means that they rely on combinations of mulches, tillage, hand labor, bio control, rotation, and cover crops for weed management, which are significantly more expensive, and one main reasons for the higher cost of organic foods.
So scientists have put their heads together try to find natural ways to deter pests so that these farmers can continue to produce organic foods at a lower cost.
We have all heard that essential oils, vinegar and fire kill off weeds, but in recent news manuka oil has taken the spot light for the best natural weed killer when used in combination with other essential oils. Commercial essential oils used alone must be applied at high concentrations up to 50–500 L of active ingredient per hectare. The cost of theses oils and the numerous applications needed are extremely expensive.
However, when manuka oil is combined with lemon grass, pine, or citrus oil it causes the weeds to loose their photosynthetic ability. This leads to bleaching, dramatic growth reduction which ultimately means plant death.
But thats not all Manuka oil does, in soil, manuka oil inhibits the growth of weeds by more than 75% displaying both pre-emergence and post-emergence herbicidal activity. It’s active ingredient, leptospermone, allows it to be stable in soil for up to 7 days and it is this soil activity that makes it superior to all other currently available essential oils commercialized for organic weed control.
This study by O’Sullivan et al. 2015 has shown that manuka oil is the first natural weed control product that has soil activity, is systemic, and when mixed with other essential oils, enhances their activity. When tested it enhanced the level of potency of lemongrass oil by 25 %, and clove oil plus cinnamon oil by 21.3 %, when tank-mixed with manuka oil versus manuka oil alone.
This research helps by providing alternatives options to synthetic pesticides. Reducing the risks to human health and the environment and allowing for effective weed control solutions with biological or natural sourced products. These solutions will improve productivity, increase yield potential/profitability, and improve the long-term competitive position of organic crop production.
So next time your experimenting with a natural pesticide for your garden try adding a few drops of manuka oil to the solution and see what happens. Just don’t get it on the plants you want to keep.
O’Sullivan, J., Grohs, R., Riddle, R., & Van Acker, R. (2015). Improved herbicide efficacy for organically grown vegetables. Organic Agriculture,5(4), 315-322. doi:10.1007/s13165-015-0107-5