HUAJUAPAN DE LEON, MEXICO -- In Peshastin many fruit growers are asking: Where are the illegal Mexican fruit pickers of yesteryear? Here, those workers have been asking themselves whether the new U.S. immigration law means that growers cannot hire them if they go to the Yakima Valley of Washington.

After a recent telephone call from relatives in Peshastin, three men in the Vasquez family and two family friends from the brown-green countryside near this dusty city of 60,000 plan to make the trip as soon as each receives the money from a relation there.

Martin Vasquez, cousin to them all and foreman at Dave Parsons' orchards in Peshastin, said those five men qualify to apply for U.S. residency under a provision in the new law for seasonal agricultural workers (SAWs) who worked in U.S. fields last year. But Martin said four other relatives should not come: They don't qualify.

If the same wait-and-see approach has been common all over Mexico, the labor shortage some U.S. farmers are complaining about may be real. Even more, the shortage may not go away soon if, after waiting later than usual to go, other families like the Vasquezes send mainly persons who qualify under the SAW program.

Mexican experts in immigration said there may be only a fraction as many Mexicans who qualify as U.S. officials assumed when the law was drafted.

Still, so few people have even begun the complex process of seeking to qualify that it is clear that most undocumented Mexican farm workers crossing the border for this harvest season are doing so illegally. The dismal state of Mexico's economy provides strong incentive for some to do so but makes the trip more difficult to afford.

The three Vasquez men intend to cross the frontier illegally, too.

"We think getting the permit is going to take a lot of time," Martin's distant cousin Ismael said, "so our plan is to go the way we did before." That method is to take a bus to a Mexican city on the U.S. border and then to pay a guide, known as a "coyote," to lead them across an unguarded spot into the United States. Once in the United States, they hope to take a bus or plane to Seattle and go from there to Peshastin.

Moises Vasquez, another cousin, said they hear that this year the "coyote" will cost $200. That is twice as many dollars as last year, but in the fourth year of constant devaluations of the Mexican currency, it is four times as many pesos.

The regional minimum wage in this the second-largest city in the state of Oaxaca, is about $2.25 a day. So an industrious Mexican peasant can earn in one hour of picking applies in Peshastin as much as he can earn here in a week.

Ismael said they will worry about getting temporary residency cards after they arrive in Washington state. The SAW program to legalize undocumented aliens who spent part of last year harvesting perishable crops in the United States is apart from the provision that gives permanent U.S. residency to undocumented aliens who can prove they have lived in the United States since Jan. 1, 1982.

The rub, said Gustavo Verduzco, a sociologist at the prestigious Colegio de Mexico in Mexico City, is that his surveys show that only one out of five Mexicans who cross illegally to work temporarily in the United States does so every year.

Thus, Verduzco said, there may be far fewer seasonal agricultural workers who both qualify and want to go back than was assumed when U.S. growers won the legislative battle to create the program as a way of assuring their labor supply. "Half went once and never went back," he said. "The other half went back at some point in their lives, but only 20 percent go and come regularly."

No one knows how many people qualify under the SAW program. The U.S. Immigration and Naturalization Service made plans to process 800,000 such workers in the United States and 200,000 abroad, according to Michael Tominski, INS director for Latin America. They had estimated that 90 to 95 percent of those people are Mexican citizens.

But Manuel Garcia y Griego, a specialist in U.S.-Mexican relations at the Colegio de Mexico, figures that only about 320,000 Mexicans qualify under the SAW program. "We're going to find out who's right, aren't we now?" he said.

Many people in the United States and Mexico, in and out of government, are confused about the effects of the Immigration Reform and Control Act enacted last Nov. 6. That is partly because the new law is so complex and partly because it is so new that its assumptions are untested.

Martin Vasquez's recent phone call from Washington state finally gave the Vasquez clan an understanding of how the law applies to them. "People were a little confused before," Ismael Vasquez said. "But basically, now we know that if you went last year, you can go, and if you did not, you cannot."

That is not entirely correct. Another provision of the law would give entry visas to new temporary agricultural workers for a season. Under that program, known as H2A, U.S. farmers can get approval from three U.S. agencies to bring in specific numbers of aliens for a single season. Employers must pay transportation costs.

But would-be workers cannot initiate the process, and they cannot regularize their status after entering the United States illegally.

To judge by what is happening with the SAW program, U.S. employers and Mexican farm workers may take so long to figure out how it will work as to have little effect on this year's harvest.

The detailed regulations that U.S. agencies need to implement the law were not finished until early May. And it is just three weeks since the U.S. Embassy, 170 miles northwest of here in Mexico City, began to mail a SAW information sheet (in Spanish that is difficult by peasant standards) to people who have requested them.

Returning a request for the application is just the beginning. U.S. consular officials said it may take as little as three days to process an application, but Mexican workers may need weeks or months to gather all the documentation they need.

Under pressure from western growers and legislators, the U.S. immigration service recently began revising its regulations to try to ease the flow of Mexican farm workers. As a result, persons who believe they qualify under the SAW program can apply at a border crossing, pay a fee and enter the country. Last week, the deadline for applying in the United States for residency under the SAW program was extended retroactively to June 26.

The deadline for applying from abroad or at a U.S. port of entry is Dec. 1, 1988. The Vasquez men plan to ask their former employers for help in applying after they arrive in Washington.

Inflation, devaluation and unemployment have made it almost impossible for Mexican workers to gather enough money to go to the United States without help from a friend or relative already working there. Through just such a support system, economic progress has been achieved in the Vasquez family for nearly 30 years.

Under the old bracero -- or laborer -- program for temporary agricultural workers that ended in 1962, Antonio Vasquez and his late brother, Josefato, first cousins to Martin's father, were the first to go the United States to work in 1959.

The second year, they got to the Peshastin area. When the bracero program ended, they kept returning illegally.

Their father had five sons, but only about half an acre of sloping land up a dirt road into the grassy, cactus-dotted hills about five miles outside of town.

The rutted road and the eldest brother, who inherited the land and the thatched hut of sticks, are still there. All three Vasquez men bound for Peshastin live in houses of varying degrees of tinyness and squalor along that lane.

The family friends who were sent for -- brothers Mario and Antonio Lucero -- live a couple of miles away through the fields. Antonio said his 90-year-old grandmother says the two families "have always known each other."

A reporter found no household along that road in which anyone unrelated to one of those two families is working or has worked in the United States. Among the Vasquezes and Luceros, there is no household where someone has not.

Ismael Vasquez, who now has an adobe house and a pickup truck, has been going to Peshastin for 10 years. Manuel Brito Vasquez, who has been going for 12 years, has a concrete-block house. Antonio Lucero, who went for the first time last year, was working last week on a cement-brick addition to the family residence.

About 100 yards down an eroded hill from Ismael, his wife's sister, Eliesa Gonzalez, lives in a one-room adobe house with her nine children. She uses the money her husband, Juan Ramirez, sends from Peshastin to feed the family.

"A year ago, we planted, and nothing grew because there was no rain," she said. "This year, it's better, thanks be to God. It's raining, more or less, so we have a little more to eat than tortillas and beans."

Antonio Vasquez lives in town now, in a house he built in four stages. He thought of going to Peshastin again this year, then found out he does not qualify under the SAW program because he has not been there in six years.

He had stopped going after buying a taxi and a van. His son, Marco Antonio, intended to go to Peshastin with his cousins this year until they found out he did not qualify as a seasonal agricultural worker.

Martin's father, Tomas, lives around the corner. He did not go to Peshastin last year because Martin's mother has been ill. But after his Peshastin years, he has two neighborhood grocery stores.

Still another cousin in Martin's generation, Leonidas Vasquez, tried to go illegally for the first time this year. On his third try at crossing the border, he heard shots, got scared and went home. Such stories and widespread rumors of mass deportations, Mexican experts said, are another deterrent to workers thinking of making the journey for the first time.

Two of the five first-generation Vasquez brothers are U.S. citizens and live near Peshastin. The brother who first went north with Antonio died in an accident in Washington in 1964.

In schooling, none of that first generation of Vasquez brothers went further than the third grade. Many of their children, Martin's generation, got as far as high school. Antonio's daughter, Leticia, is an unemployed accountant.

The Vasquez family experience tends to support Garcia y Griego's findings that most Mexicans no longer cross the border to meet what they perceive as basic needs. "In most cases, it is because they want to build a house or add on to one, because the guy plans to get married and needs furniture or because his daughter is going to get married," Garcia y Griego said.

"Relatively few see themselves as needing the money to feed their families, so they may perceive themselves as having time to see what happens with the new law," he said.

The Vasquezes are cynical about the new law. "In 1970, they were also going to put in a new law, and my {American} boss said they wouldn't be hiring any illegals, but after a while, things were the same as before," Antonio Vasquez said.

"Well, we're going to see with the new law this time," he said. "There'll be a lot of losses in the harvests, and then they're going to change things. Two of us illegals still can pick as much as 10 Americans."