Pesticides
The quotations in this blog are from the text book Environmental Chemistry (3rd ed.) by Colin Baird and Michael Cann, published in 2005 by W.H. Freeman and Company, New York.
"All chemical pesticides share a common property of blocking a vital metabolic process in the organism to which they are toxic." (p. 307). That is how synthetic chemical pesticides work. The term pesticide refers to herbicides, fungicides, insecticides, etc.
It is both a great good to have pesticides, and a great health risk to health and the environment. "...even with extensive use of pesticides, about one-third of the world's total crop yield is destroyed by pests or weeds during growth, harvesting, and storage." (p.309). So it is a good thing scientists have developed pesticides in order for us to enjoy all the wonderful foods we do.
However, these inventions come with dire side effects. "Unfortunately, inorganic and metal-containing organic pesticides are usually quite toxic to humans and other mammals, especially at the dosage levels that are required to be effective pesticides...In addition, toxic metals and semimetals, such as the arsenic commonly used in such pesticides, are not biodegradable..." (p. 310). So since pesticides contain chemicals that are toxic to humans and other organisms AND the persist in the environment, it seems wise to avoid directly using pesticides in our daily lives.
There are natural pesticides available, containing ingredients derived from chrystanthemums (pyrethroids) and bean roots (rotenone). These natural pesticides biodegrade in sunlight. Yet, they are not benign. "...pyrethrins and rotenone, which are natural substances, have about the same acute toxicity as some synthetic ones, such as malathion, even though they are often marketed as safer, natural pesticides. Unfortunately, there is some evidence that chronic exposure to rotenone can contribute to the onset of Parkinson's disease." (p. 343). So again, it seems that even natural pesticides are best avoided.
Biodegradable products are kind of a half baked invention themselves. The chemicals the product turns into through decomposition have likely not been tested for toxicity and persistence in the environment.
In light of all these negative side effects and uncertainty, it's best to simply avoid using pesticides until a truly non-toxic remedy is found. This attitude can be called the precautionary principal, defined at the 1992 Rio Conference on Environment and Development as such, "Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation." (p. 335). Pesticides cause damage to the ecosystem directly through toxicity and indirectly through their decomposition or persistence in the environment. So, we can turn to organic gardening, which seeks to enhance the ecosystem's natural defences instead.
Preventative methods that keep your plants as healthy as they can be, and therefore stronger and better able to naturally fend for themselves include:
- choosing plants that suit the situation/modifying the situation to suit the plants (native plants are perfectly suited to the natural environment),
- feeding with organic fertilizers which naturally contain micro-nutrients and encourage beneficial microbes in the soil,
- consistent watering in amounts and methods the plant naturally likes,
- having a source of water in the garden for good bugs and birds, and
- leaving some leaves all winter, incorporating rotting logs, rocks and a patch of long grass to provide homes for beneficial bugs, like ground beetles and native bees.
While avoiding pesticides, we can become more tolerant of bugs. Pest bugs attract their natural predators, which will diminish the pests. In turn, bugs will attract song birds and hummingbirds etc.
Think of Rachel Carson and her book Silent Spring!