For decades now, I have tried to be as responsible as possible when it comes to the use of chemicals. In my work with trees, I have found for the most part that chemicals seldom solve any tree problems but frequently can create more problems than they solve.
Insecticides are a good example. Toxic sprays such as Orthene® and the like kill all of the beneficial insects as well as the targeted pests. That doesn’t even take into consideration what happens to the poor person applying the chemicals. (The man I first learned to climb from died of stomach cancer at the age of 66 after a lifetime of using a variety of chemical insecticides including DDT.)
For decades, pyrethrins have been touted as the safe alternative for the environment. Originally made from chrysanthemums, the pyrethrins are supposed to be safe for everyone except the targeted insect. Of course pyrethrins are now artificially synthesized (called pyrethroids) and show up in so many products, I’ve lost count. The next time you’re in a hardware store, look to see how many of the insecticides have the suffix “thrin.” It’s become the most popular insecticide everywhere.
Farmers looking for safer alternatives have turned to pyrethrins in greater and greater numbers to where organophosphates have been overtaken by pyrethrins.
Because these chemicals have been labeled “safe” and “organic” or “natural,” no one has been looking for pyrethrins in the environment (until now.) When scientists recently went looking for five pyrethroids in a 10 county area of Central California, they found one or more of the chemicals in 75% of the samples they took. Of these samples, they found the levels toxic to crustaceans living in the sediment.
Not confined to farm field run off, toxic levels of pyrethroids have also been found in city waterways as well. More and more, people are using pyrethroids on their lawns and gardens and the run off is polluting our rivers and streams. Indeed, the highest concentrations were found in suburban creek sediments – 10 to 15 times as high as sediments adjacent to farmland. Researchers conclude that much of the contamination comes from lawn care products.
Pyrethroids are as harmful to aquatic life as DDT. They poison by wreaking havoc on the nervous system. Since the nervous systems of crustaceans and many soft-bodied aquatic animals closely resembles that of insects, non-targeted animals are vulnerable to pyrethroids.
In my opinion, it is best to use a variety of alternatives to insecticides whenever possible. The release of beneficial insects helps bring the balance back to nature. The use of simple sprays where ever possible works relatively well. The first line of defense should be the least possible toxic when combating insect infestations. One needs to make the determination of what the threshold of damage is before jumping on the insecticide wagon. Most insect damage in healthy plants is far below the threshold of lasting harm. Educate your clients in what the damage threshold is before agreeing to spray everything in sight.
On small shrubs and tree, some insect populations can be kept in check by the homeowner with simple cultural techniques that prevent plant stress.
“Mechanical” sprays such as soaps or oils will smother the targeted insect without leaving behind toxic residues.
Bringing a tree or shrub into better heath by improving its growing environment will allow the tree to survive minor insect damage without the need for spraying.
Think before you spray. Use a simple jet of plain water from the garden hose. You might be surprised at how well it can work when used repeatedly.