This is the VOA Special English Agriculture Report.
Agriculture around the world depends on chemicals that controlthe growth of unwanted plants. Poisons that generally affect onlyunwanted plants, or weeds, are called herbicides. However, manyherbicides are losing their ability to kill weeds.
Scientists have known for years that weeds develop resistance toherbicides. Now, a growing number of weeds are developing resistanceto the world’s most popular weed killer. The American companyMonsanto makes the herbicide. Its trade name is Roundup.
Roundup has been developed for use with genetically engineeredcrops. These crops are called Roundup Ready. Growers can put theherbicide directly on the crop. It kills all unwanted plants. Yet,the crop remains unharmed.
Corn, cotton and soybeans have all been genetically engineered tobe Roundup Ready. The use of these two products together greatlysimplifies crop raising for farmers in many countries. Aboutseventy-five percent of all soybeans and sixty-five percent of allcotton grown in America is Roundup Ready.
However, some experts say that herbicide-resistant weeds couldcause serious problems. Resistant weeds could quickly overgrow afield, destroying the crop. Some experts say this is alreadyhappening in areas of Delaware, Maryland, Virginia and New Jersey.
Normally, farmers grow different crops in a field from year toyear. This method is called rotation. It reduces the possibilitythat weeds or insects will become resistant to chemicals. Yet, onlyone herbicide is needed for all Roundup Ready crops.Herbicide-resistant weeds could ruin all Roundup Ready crops on afarm.
Scientists developed another kind of genetically engineered cornto resist insects. It is called B-T corn. Currently, the EnvironmentProtection Agency requires farmers who grow B-T corn to plant otherkinds of corn in nearby fields. This measure is meant to keepinsects from developing resistance to B-T corn. However, no ruleexists for Roundup Ready crops.
Experts from Monsanto say only about four kinds of weeds haveshown resistance to Roundup. This is a very small number of cases.Some other herbicides are not effective against as many as seventykinds of weeds. However, the number of resistant weeds has increasedevery year.
This VOA Special English Agriculture Report was written by MarioRitter.