I have read recently, in issue 305/2011 of the Journal of the American Medical Association *, that researchers from the National Institute of Environmental Sciences and the Parkinson’s Institute and Clinical Center in California are associating the use of pesticide substances rotenone and paraquat with an increased risk of developing Parkinson disease. My first thought about the results of this research was that, once again, some chemical substances prove to be harmful to people. The incrimination of chemistry was in this particular situation only half true.
Rotenone is an odouless chemical substance that occurs naturally in the roots and stems of various plants. Although rotenone has high acute toxicity via the oral and inhalation routes of exposure and low acute toxicity via the dermal route of exposure *, due to the fact that it bio-degrades rapidly under warm conditions, in many countries its correct use – even for fishing (poisoning of water and collection of dead fish) – was until recently considered safe *. However, since 2008 the Federal Health Department of Canada has issued a re-evaluation note concerning the use of rotenone. According to this, the sale and use of domestic and commercial class rotenone products will be banned in the country after year 2012 *.
Paraquat is one of the most widely used herbicides in the world. It is used for the protection of crops especially due to its fast and effective action *. In Denmark the sale and use of this herbicide is constricted since 1994 *, but in December of 2003 paraquat use was approved by the European Union. This decision was questioned by many governments, among them the Swedish, since many independant studies have shown that paraquat contains some extremely toxic substances *.
Chemicals or not, the above mentioned substances and many more are disputable and severe concern about their use is expressed. As far as crops are concerned researches and agronomists are the most qualified people to give information and directions. But if you have a garden or balcony and gardening is your hobby, there are many alternatives to pesticides that could protect your plants and pose lower health risks for you and your family.
The use of essential oils is one of them. In 1997 Catherine Regnault-Roger of the Pau et des Pays de l’Adour university in France wrote: “aromatic plants and their essential oils are among the most efficient botanicals. Their activities are manifold. They induce fumigant and topical toxicity as well as antifeedant or repellent effects. They are toxic to adults but also inhibit reproduction. Although mechanisms depend on phytochemical patterns and are not yet well known, this widespread range of activities is more and more being considered for both industrial and household uses. Essential oils are presently regarded as a new class of ecological products for controlling insect pests *.”
In the book “Agricultural Application in Green Chemistry” which was published in 2004 by the American Chemical Society, researcher Murray B. Isman reports: “recent investigations indicate that some chemical constituents of these oils interfere with the octopaminergic nervous system in insects. As this target site is not shared with mammals, most essential oil chemicals are relatively non-toxic to laboratory animals and fish in toxicological tests and meet the criteria for “reduced risk” pesticides.” And he concludes: “though well received by consumers for use against home and garden pests, these “green pesticides” can also prove effective in agricultural situations, particularly for organic food production.”* The article “Plant essential oils for pest and disease management” written by the same author is also very interesting and you may read it here .
According to a research that was carried out in India and published in 2008 “the use of eucalyptus oil as a natural pesticide is of immense significance in view of the environmental and toxicological implications of the indiscriminate use of synthetic pesticides and overcoming/reducing the problem of increasing pest resistance.” *
The essential oils that stand out for their insect repellant attributes are peppermint, spearmint, eucalyptus, juniper, lavender, rosemary, lemongrass, lemon, cinnamon, patchouli, thyme, neem and garlic (which should be used with care because it also kills beneficial insects and microbes). You can prepare an effective pesticide by adding 15-20 drops in total of the aforementioned essential oils in 120 ml water. Essential oils evaporate fast and bio-degrade rapidly under sunlight *. Therefore, you may need to spray the plants more frequently than when using a commercial pesticide, approximately every 3-4 days.
Another method to protect your plants without using pesticides is biological control. That is, releasing in your garden or balcony bugs that are natural enemies of the ones you want to get rid off. A typical example is the ladybird beetle which not only brings good luck to a home but also can eat up to 24 insects a day (aphids, mealy bugs and scale mites) *. This method has significantly evolved the last few years because it is a natural, safe and effective alternative to pesticides. I was surprised by the fact that 8 companies in Australia raise and sell “good bugs”. You can find more information about biological control in the Austalian Association of Beneficial Arthropod Producers’ site.
Enlightening books about the topic: