This is the VOA Special English Agriculture Report.
Since nineteen-forty-five, farmers have used pesticides, poisons made from chemicals, to kill insects that damage crops. One serious problem with pesticide use is that people get sick. Every year about five-hundred-thousand people are poisoned by pesticides. About ten-thousand people die.
Some scientists are working to develop other ways to keep insects and disease organisms from harming crops. One method is to choose plants that show a natural resistance to certain insects. Then these plants are used to produce new plants. The new plants will have more resistance than the parent plants. For example, corn or maize plants grown to have more Vitamin A than normal plants can fight off insects that feed on their leaves.
However, if levels of Vitamin A get too high, humans and animals that eat the maize may get sick. So it is important to study this kind of insect control very carefully.
Some plants produce natural poisons against insects. For example, potato plants produce poisons everywhere in the plant, including sometimes in the potato itself. These poisons kill insects. But they can also kill people. People should never eat potatoes that have turned green after being left in the sun.
Another method is to plant crops when the harmful insects are not present. In this way the plants grow before the insect population gets too large to damage them. Grains such as wheat and barley are planted in this way to protect them from an insect known as the Hessian fly.
Water also can be used to limit harmful insect populations. One method is to add a lot of water to alfalfa plants growing in a field. Other smaller plants grow and limit insects like aphids. Limiting water in certain situations can have the same effect.
Turning over the soil, called plowing or tilling, is a way to keep small organisms that cause disease from attacking the plant. Like the other methods, this must be done with care. Plowing can cause soil to be blown away by wind and water. The loss of soil from plowing has become a major environmental problem around the world.
You can get more information about pest management from the group, Volunteers in Technical Assistance. You can contact VITA through the Internet at its world wide web address w-w-w dot v-i-t-a dot o-r-g.(www.vita.org)
This Development Report was written by Gary Garriott.