By Bob Bowen
Broadcast: March 22, 2005
I'm Gwen Outen with the VOA Special English Agriculture Report.
Agricultural scientists are continually looking for new ways to improve crops, control insects and reduce the need for chemicals.
It is a never-ending search. It often results in finding a solution for one problem while making another problem worse.
Sometimes, however, farmers can solve several problems at the same time. They can do this by carefully choosing the crops they plant in the same field.
In the early nineteen nineties the magazine Organic Gardening, from the Rodale Institute, published some studies on this subject.
There was advice from a scientist named Kimberly Stoner, an insect expert at the Connecticut Agricultural Experiment Station. She said farmers can keep flea beetles out of broccoli fields by planting clover in the same field.
Flea beetles cannot find broccoli when it is surrounded by clover. So the insect flies away in search of broccoli that is growing in a field without clover.
Another method of protecting the main crop is to plant it in the same field with some plants that insects do not like.
For example, the Colorado potato beetle does not like tansy because of the strong smell of this herb. So researchers at the Rodale Institute planted tansy in several potato fields.
The population of Colorado potato beetles was reduced anywhere from sixty to one hundred percent. The reduction depended on the amount of tansy planted. Studies done later in a laboratory showed that tansy produces a natural chemical that keeps the potato beetle at a distance.
In fact, some insects like weeds more than they like crop plants. Scientists did some research at the Subtropical Cotton Insects Research Station in Texas. They planted ragweed and pigweed in a field of bell peppers.
Leaf miner insects can destroy a bell pepper crop. But, when given a choice of bell peppers or ragweed and pigweed, the insects chose the weeds.
In another experiment, researchers in India planted cabbage and mustard greens in the same field. They were attempting to control diamondback moths and leafwebbers. In three separate tests, the insects chose the mustard greens instead of the main crop, the cabbage.
Next week, we will discuss how some plants help each other through their root systems. And we will discuss how some plants attract helpful insects that feed on harmful insects.
This VOA Special English Agriculture Report was written by Bob Bowen. I'm Gwen Outen.