This is the VOA Special English Agriculture Report.
Since nineteen-forty-five, farmershave used pesticides, poisons made from chemicals, to kill insectsthat damage crops. One serious problem with pesticide use is thatpeople get sick. Every year about five-hundred-thousand people arepoisoned by pesticides. About ten-thousand people die.
Some scientists are working to develop other ways to keep insectsand disease organisms from harming crops. One method is to chooseplants that show a natural resistance to certain insects. Then theseplants are used to produce new plants. The new plants will have moreresistance than the parent plants. For example, corn or maize plantsgrown to have more Vitamin A than normal plants can fight offinsects that feed on their leaves.
However, if levels of Vitamin A get too high, humans and animalsthat eat the maize may get sick. So it is important to study thiskind of insect control very carefully.
Some plants produce natural poisons against insects. For example,potato plants produce poisons everywhere in the plant, includingsometimes in the potato itself. These poisons kill insects. But theycan also kill people. People should never eat potatoes that haveturned green after being left in the sun.
Another method is to plant crops when the harmful insects are notpresent. In this way the plants grow before the insect populationgets too large to damage them. Grains such as wheat and barley areplanted in this way to protect them from an insect known as theHessian fly.
Water also can be used to limit harmful insect populations. Onemethod is to add a lot of water to alfalfa plants growing in afield. 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 tokeep small organisms that cause disease from attacking the plant.Like the other methods, this must be done with care. Plowing cancause soil to be blown away by wind and water. The loss of soil fromplowing has become a major environmental problem around the world.
You can get more information about pest management from thegroup, Volunteers in Technical Assistance. You can contact VITAthrough the Internet at its world wide web address w-w-w dot v-i-t-adot o-r-g.(www.vita.org)
This Development Report was written by Gary Garriott.