Organic pesticides have been praised to the heavens for many years by proponents of the organic cultivation method, but there are increasing doubts over their safety and efficacy. For many, 'organic' equates to 'better', 'healthier' and 'safer', but ultimately, all pesticides are poison, even those derived from natural sources.
Organic pesticides have been praised to the heavens for many years by proponents of the organic cultivation method, but there are increasing doubts over their safety and efficacy. For many, ‘organic’ equates to ‘better’, ‘healthier’ and ‘safer’, but ultimately, all pesticides are poison, even those derived from natural sources.
The best pesticide is no pesticide
With the correct degree of care and attention to detail, it should be possible to maintain a grow without resorting to pesticide use at all—keeping plants tidy and well-maintained, keeping the grow room or surrounding environment clean and tidy, and ensuring optimum conditions to promote healthy plants will all go a long way towards keeping an organic garden free from infestations.
However, there are times when even the most fastidious gardener may become overwhelmed by spider mites or whitefly, and in these cases, it is important to have an awareness of the effects and possible consequences of the various pesticides available, so that the most appropriate one can be used.
Environmental Impact Quotients for common pesticides
A look at the Environmental Impact Quotients (EIQs) for some popular insecticides, both organic and synthetic, yields some surprising results. Many of the best-known organic insecticides have high EIQs, as high or even higher than their synthetic counterparts: rotenone is derived from plant sources and has a EIQ of 29.43; sabadilla (derived from the Schoencaulon officinale lily) has an even higher EIQ of 39.41.
To compare, synthetic insecticides such as Carbaryl and Malathion have EIQs of 22.73 and 23.83 respectively. This does not mean that synthetic chemicals are generally less harmful than organics; indeed, some of the most dangerous synthetic organophosphates, such as fipronil and disulfoton, have EIQs of 88.25 and 101.83 respectively.
Some organic pesticides are highly toxic
However, the belief that a pesticide is better purely through virtue of being organic is clearly erroneous, if not dangerous. Many organic insecticides are powerful neurotoxins, causing slow, painful deaths in the species worst affected. Humans are often moderately affected, but populations of birds, fish and beneficial insects such as bees can be wiped out if exposed.
Some infestations are more effectively treated by synthetics: the number of applications required to provide the necessary protection is often fewer with synthetics, and the half-life and resultant by-products are fewer and less contaminating than with certain organic insecticides such as rotenone.
Organic pesticides may contribute to CCD
In fact, rotenone’s severe toxicity to fish, birds and bees has led to it being banned in many countries including the U.S. and Canada. Rotenone, sabadilla and many other organically-derived insecticides such as pyrethrins have been implicated in colony collapse disorder (CCD)—the mass honeybee deaths that have been occurring worldwide over the last few years.
However, although some organic pesticides may be more environmentally harmful than their synthetic counterparts, there are several which rank very low on the EIQ scale, and which have no known ill-effects on humans or beneficial insects.
What are the safest organic pesticides?
Insecticidal soap is one of the safest organic chemicals. Harmless to bees, humans and domestic animals, these potassium-based fatty acids break down the cell membranes of soft-bodied pest insects such as aphids, spider mites and whitefly. While not toxic to humans, these soaps can cause mild irritation and may also cause plants to develop ‘spots’ or burned-looking patches with heavy use.
Neem oil is another relatively safe organic pesticide. The pungent, bitter oil acts mostly as a repellent, but can also break down various species of insect larvae. It is non-toxic to humans and honeybees, but can cause mild toxicity in cats and dogs.
Finally, Bacillus thuringiensis, also known as BT, is a microbial insecticide—a bacteria that paralyses the digestive system of many undesirable species. BT is potentially the most important tool in the organic gardener’s armoury when it comes to insecticides: there are various strains of the bacteria which can be bio-engineered to only attack certain species, and there are no known long-term effects on the health of any non-targeted species.
Genetically engineered pesticides
Geneticists are already working on incorporating engineered strains of BT into the DNA of valuable crop plants, so that the plant will manufacture its own insecticide as it grows. These modified plants will then seed, and their offspring will also have the introduced bio-defense mechanism in their genetic material.
While this could negate the need for pesticides once and for all, there are various questions currently being raised as to whether this could ever be seen to constitute organic farming, as there is a necessary degree of genetic modification at work. However, provided that the modifications can be proven to be safe, there would be few other ethical reasons to dismiss such future-thinking technology.
The goal is to produce healthy, safe and effective cannabis without causing harm to any part of the ecosystem, and the techniques by which to do so are improving with every day. If managing one’s own organic garden, it is highly advisable to stay up-to-date with current research, as our understanding of the processes involved is changing constantly.