Driving through the Lower Rio Grande Valley in southern Texas, it is clear that whatever labor is being done on a farm -- be it driving a tractor or weeding a field -- Latinos are doing it.

This is especially true for labor-intensive crops such as citrus fruits, which require unskilled but physically demanding harvesting under a blazing sky, and the mind-numbing task of sorting produce on a conveyor.

As the United States grapples with the fallout of a failed attempt to overhaul immigration policy and set up a migrant worker program, one thing is clear: U.S. agriculture is utterly dependent on migrant labor.

If the Mexican farm laborers all went back tomorrow, the U.S. farm system would collapse, said Bobbie Brown, a crop farmer in the lower Rio Grande Valley along the Texas/Mexico border.

Of 17 workers sorting limes from 40 pound bags into 2 pound bags on a conveyor belt in Mission, Texas, all were Latino and almost none could speak English. The limes were grown in Mexico and will be distributed in U.S. grocery stores.

I'll soon go to Oklahoma and Colorado to pick watermelons. Then I'll be back here in September, one of them, who declined to give his name, told Reuters.

Crops ranging from cotton to corn are grown in the area, much of it in the cooler winter months. Fields of sugar cane and some hardy corn were growing under a blazing July sun.

William Kandel, a sociologist with the U.S. Department of Agriculture's Economic Research Service, said it was difficult to estimate the numbers of farm workers and the percentage of the labor force which came from south of the border.

Government surveys suggest that there are roughly 700,000 to 850,000 hired farm workers, on average, at any given point during the year in the United States. There are academic estimates that put the figures substantially higher at between 1 and 1.4 million, he told Reuters.

A recent National Agricultural Workers Study (NAWS) by the department of labor which surveys crop workers in the field found that 75 percent of hired hands in the sector were from Mexico and five percent were born in other foreign countries.

It also found that about half were undocumented.

IMMIGRATION REFORM SOUGHT

Texas Produce Association president John McClung said that the industry wanted a legal workforce and was on President George W. Bush's attempt to formalize the status of millions of illegal migrant workers, which was killed in June by the U.S. Senate.

We need immigration reform, not a wall, he said, in reference to a planned security fence that would run for hundreds of miles along the U.S./Mexico border.

Critics of the current system contend that their illegal status makes it easy for the farming industry to exploit many migrants.

McClung said that while some painted the industry as exploitative, the average wage for a field laborer was $9.50 an hour, not great for hard work, but higher than the minimum wage.

The industry view is that Mexico has the labor, Mexicans need the work, and Americans don't want to do these jobs. So some kind of immigration reform is required.

For obvious reasons, farmers did not admit on the record to hiring illegal workers.

One valley farmer said the vast majority of the Mexicans working the land in south Texas at least had documents but admitted that forged papers were not uncommon.

Go to most any grocery store or restaurant in America in the summertime and you will see students stocking shelves or waiting tables. But you won't see them picking crops.

But American students in search of summer work simply do not want to do the hard labor in the fields or the sorting on conveyor belts.

It's hard work in the hot sun. Americans just don't want to do it anymore, said Betty Perez, a local rancher.

Industry officials maintain that the labor shortage is worsening because the children of migrant workers are enjoying the life their parents toiled for.

Our labor situation is getting more difficult. More sons and daughters of our workers are getting educated and acquiring skills, said Jeff Brechler, a sales representative with J & D Produce Inc., a grower, packer and shipper of produce in the lower Rio Grande Valley.

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