A genetically altered plant that excretes pesticide will be tested in cotton fields around the nation this summer, a major step toward getting the first such plants onto the market.
The Environmental Protection Agency approved yesterday large-scale field tests of Monsanto Co.'s cotton plant on about 60 acres in 11 states. Approval came despite concerns that the large green caterpillar so destructive to the plant could become resistant to the pesticide.
Other genetically engineered plants have been tested in the open and are moving toward commercial markets. Calgene Inc. of Davis, Calif., is working on a tomato that does not get mushy. And Crop Genetics International Corp., a Hanover-based company, is developing a vaccine for corn seed.
St. Louis-based Monsanto could be one of the first companies to get such a product to market, but that won't happen before 1995, said Jim Altemus, Monsanto's plant biotechnology information manager.
To make the cotton plant, Monsanto researchers injected plant cells with a gene from the bacterium Bacillus thuringiensis (Bt), which is widely used as a pesticide.
When bollworms come along to chew up the new cotton plant, they will get a taste of a toxin that kills them.
If the new plant works, it could help farmers reduce their use of pesticides and limit damage from the bollworm, which cost cotton farmers $193 million in 1990.
The new plant will be tested in Alabama, Arizona, Arkansas, California, Georgia, Hawaii, Louisiana, Mississippi, North Carolina, South Carolina and Texas.
The use of the altered plant is controversial. Questions remain about whether pests will become resistant to the plant and, therefore, to Bt, which is used on many plants.
Maryland uses the pesticide on oak trees, for instance, because it is the safest one available for protection against gypsy moths.
Monsanto thinks there is only a slim chance that the bollworm will become resistant to Bt. Mr. Altemus said the company might take some measures to reduce the risk, such as using two strains of Bt in the plants and mixing the seed of genetically altered plants with other seed so that a farmer will not grow only altered plants in one field.