The administration and the chemical industry, arguing that the Environmental Protection Agency's new leadership needs time to organize, urged Congress yesterday to approve a simple extension of the nation's basic pesticide control law.

But congressmen from Florida and New York, where recent cases of pesticide contamination have caused alarm, joined representatives of an environmental and labor coalition in calling for major amendments to the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).

These contending voices set the tone for what is shaping up as a combative rerun of last year's ill-starred congressional effort to rewrite FIFRA. Much of that debate occurred before the EPA became engulfed in controversy over charges of mismanagement, favoritism to business and conflict of interest that led to the wholesale dismissal of the agency's top appointees.

Last year the National Agricultural Chemicals Association and the Chemical Specialties Manufacturers Association pushed Congress to change the law to limit the release of scientific data and curb state powers to regulate chemicals.

Their problems haven't gone away, they told a House Agriculture subcommittee yesterday, but said that opening FIFRA to amendments while the guard is changing at the EPA wouldn't make much sense.

Subcommittee Chairman George E. Brown Jr. (D-Calif.) received general support from other members yesterday when he suggested that the easiest approach would be to extend FIFRA as is for two years, then confront thornier issues.

Edwin L. Johnson, director of EPA's Office of Pesticide Programs, and the major agricultural and domestic pesticide producers quickly warmed to Brown's suggestion. They argued that the new EPA officials must have more time to decide what legislative changes are needed.

But the environmental witnesses pounced on the idea just as quickly, saying that the EPA's problems are well known--documented in large part by a voluminous study by Brown's staff last winter--and that public-health protection can't wait.

"A simple reauthorization of FIFRA will not accomplish anything, except a continuation of problems they now have at EPA," said Maureen Hinkle of the National Audubon Society. "The committee report gave an Alice-in-Wonderland trip into the Office of Pesticide Programs."

When she said that a two-year extension, as Brown proposed, "would be shoving these problems under the rug at the worst possible time," Hinkle drew a scolding denial from Rep. Pat Roberts (R-Kan.).

Albert H. Meyerhoff of San Francisco, a staff attorney for the Natural Resources Defense Council, charged that "a national scandal" has developed at the EPA, which he said has allowed hundreds of pesticides to go on sale without the required tests for cancer, birth defects and genetic mutations.

Meyerhoff said the recent subcommittee report revealed that the EPA had failed to fulfill a 1978 congressional directive to conduct safety reviews and re-register all pesticides on the market before 1977.

"The time is ripe," he said, "for fundamental reform in this critically important statute."

Reps. Thomas J. Downey (D-N.Y.) and Bill McCullom (D-Fla.) agreed. Downey protested that FIFRA had not protected homes on Long Island from contamination by aldrin, which is used to fight termites. McCullom said laxity in dealing with Temik has created serious water contamination in Florida.