Fifteen years after he led the most successful farm strike and boycott in United States history, Cesar Chavez last night called on an emotional Law School Forum crowd to boycott table grapes in protest of unfair government and landowner practices.

"Today the growers are like a punch-drunk boxer who doesn't know he is past his prime," Chavez told an overflow crowd in Ames Courtroom, which showered him with three standing ovations during the program.

Chavez, who heads the United Farm Workers, called for "the overthrow of a system that treats farm workers like they are not important human beings."

He described in stark terms the living conditions among Chicano farm workers in California and the Southwest, decrying their "poverty and indignity." He cited high child mortality rates and extremely low life expectancies for farm workers as evidence that the migrant farm system is unjust.

Calling for an end to hunger, sexual harassment, and environmental poisoning of farm workers, Chavez said, "We have allowed ourselves to become victims in a democratic society."

Chavez sharply criticized California Governor George Deukmejian, whom he accused of "letting the growers get away with everything." Chavez said that migrant farm workers, under Deukmejian, have suffered the loss of political rights, the blockage of millions of dollars in lost wages, and rampant union- busting.

Chavez, who began organizing farm workers in 1962, founded the United Farm Workers four years later. In 1973 he called on a worldwide boycott of grapes, head lettuce, and Gallo wines, protesting growers' refusal to allow union organizing.

The boycott, which ended successfully in 1975, was supported by 17 million American adults, according to a Harris Poll. Chavez has directed a total of 27 boycotts during his tenure as UFW president, each of which he served "successful."

"Deep in my heart. I know I would never be happy if I didn't try to organize the farm workers," Chavez said.

"I couldn't understand how they [the growers] could exploit farm workers when there are so many of us and so few of them," he added. "I have tried to organize, educate, and empower the Chicano people."

Chavez forecasted a bright future for the farm workers, predicting that the descendants of migrant workers will dominate the California farm belt politically "in 20 or 30 years."

"As long as the union exists, farm workers will benefit from our existence," he said. "And we will exist forever."

Chavez, in the most emotional moment of his speech, added that "We are more than an in stitution-we are on the cutting edge of a people's cause. And you can not stamp out a people's cause."

Chavez called on all his old supporters to back the present boycott, and also asked for the help of the "new crop' of concerned citizens. He has been in Boston for the past three days to gather support of the boycott.

"There is a conservative trend in this land," he said. "Yet we have hope and encouragement.