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Controlling landscape pests – without chemicals

When it comes to landscaping there's one word that seems to evoke strong feelings from opposite sides of the subject: pesticides. It seems that there are very few people who are neutral about pesticides. Generally, you're for them or against them. But as with most things in life, it's not really that simple.

For example, not even the strongest opponent of pesticides will relish the idea of shrubs, plants and trees – particularly fruit trees – being infested with bugs. On the other hand, randomly spraying killer chemicals on plants won't seem like the ideal solution even to the most ardent entomophobe. (Yes, entomophobia is the clinical name for the morbid fear of insects!)

Today, I'll discuss ways to control insects in your landscape, and ways to avoid injuring yourself, your plants, your animals and the environment.

First, it must be said that pesticides are potentially very dangerous, and not solely to insects.

Pesticides are the number two cause of household poisonings in the U.S. About 2 million people and countless companion animals are affected each year by common household pesticides such as fly spray, roach bait, and insect repellents. More than half of those who die from pesticide-related poisoning are children, according to an article at http://www.homesafetycouncil.org/encyclopedia_d09_lawn.asp There's a direct link to the entire article at my web site, www.landsteward.org Find this column under the heading "The Plant Man" and click on the link.

The people at the Home Safety Council say that a respirator should be worn whenever pesticides or other chemicals are mixed and/or applied. Good respiratory health depends on breathing air that is clean, odorless and leaves no taste. However, there are many dangerous contaminates that are invisible and tasteless. So when in doubt wear a respirator to protect your respiratory system.

The safest route, of course, is to control pests in ways that use little or no chemicals at all. If you're interested in this alternative you might want to investigate a program called Integrated Pest Management (IPM). Try your favorite search engine, such as Google, or you can go to a long and very useful article from the Oregon State University Extension Service located at http://eesc.orst.edu/agcomwebfile/edmat/html/ec/ec1532/ec1532.html#anchor187772 (As always, there's a link from this column at my web site to save you keying in that long address!)

First things first: Before you even THINK of reaching for the pesticide, be sure that the problem really is caused by insects. Most plant problems in gardens and landscaping are due to a nonliving factor such as poor growing conditions, temperature extremes, poor water management, soil compaction, or mechanical injury, according to the researchers at OSU..

It is important to remember that many organisms do no damage, and many others are beneficial. Make sure the organism you identify actually is the one doing the damage and not just one that happens to be present.

That is a very important point to bear in mind, because you might be seeing the insects that are present in order to feed on the organisms that ARE causing the damage! Eliminate them and you have eradicated an excellent – and completely natural – way to control damage-causing organisms.

There are approximately 100,000 species of insects in North America and only about 10 percent could be described as harmful. The majority of insects are neutral (from the point of view of your landscape), but around 20 percent could be described as truly beneficial, particularly those that like to chomp on the real villains such as aphids and termites.

So it makes sense not to eliminate the "good guys" from your plants. But it isn't necessarily a good idea to eradicate ALL the "bad guys"either. Why? Because once they are all gone, there's no reason for the bugs that feed on them to stay around. They leave or die out... and the "bad guys" soon return in full force.

So the phrase is pest control, not pest elimination.

The OSU site I mentioned above has numerous ideas for controlling pests with a variety of methods including plant collars and cages, sticky barriers and metal barriers that help to prevent pests from reaching the plants.

When the insects have already infested your plants, two non-chemical treatments that are very effective. Dislodge the bugs by spraying them directly with water. Use a clean spray bottle rather than a garden hose that could damage delicate plants. Remember to look on the underside of leaves.

You can also take your hand-held vacuum outside, too. Just suck the little critters off the leaves. Vacuuming works best with insects such as white-flies and spider mites that congregate in groups and do not scatter when disturbed. Empty the vacuum bag into a plastic baggie, freeze and discard.

Most plants can survive quite well despite a little insect damage. However, it's important to select healthy plants that will be strong enough to thrive even when hosting a few pests. Let me know, via e-mail, if you need some specific plant ideas for your landscape. The less you need to rely on chemicals, the better for all concerned!

The Plant Man is here to help. Send your questions about trees, shrubs and landscaping to [email protected]ndsteward.org and for resources and additional information, including archived columns, visit www.landsteward.org often.



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