The farmworkers go at a furious pace, kicking up clouds of dust as they crouch down to grab several tomatoes at a time, put them in plastic buckets and hurry them over to be weighed.
The workers are all identified by numbers on this ranch in a dusty valley of Mexico's Baja California peninsula, where the work day starts at 6:00 am and lasts between nine and 14 hours.
"Number 10!" "Number 24!" "Five!" they call out as they dump their 20-kilogram (45-pound) buckets, racing to reach their daily quota.
They have to pick a minimum of 700 kilograms to earn a day's pay of 120 pesos ($7.80).
Each extra bucket earns them a small bonus. The best manage to pick three tonnes, enough to fill one of the trucks that transport the tomatoes to wholesalers in the United States.
Across the border, a truckload sells for $2,000. The Mexican day laborer gets $16, if he can fill a whole truck.
In the strawberry fields nearby, workers go home with as little as $2 in their pockets on a bad day.
The harsh conditions that the region's day laborers long endured in silence came into focus last month when 30,000 of them went on strike, holding protests that ended in clashes with police and hundreds of arrests.
But, unable to make ends meet, they have been forced to return to work as negotiations continue with their employers and the government.
- 'Like animals' -
"That's our life. You have to work to eat. You can't live on nothing. We're used to this from the age of 14 or 15," said Paulino Jose, who at 72 is still working and has no plans to retire.
Jose was part of a wave of rural Mexicans who migrated from the poor southern states of Oaxaca and Guerrero in the 1980s seeking a better future in San Quintin, the heart Baja California's agriculture industry.
Today, about 80,000 of Mexico's two million day laborers work in the region.
For many, the backbreaking work in punishing heat, farming strawberries, tomatoes and other red fruits for export to the United States, is the only world they know.
Maria and Cresencio, both aged 35, started working in the fields at seven years old.
They grew up there, fell in love there and continue toiling there every day to scrape out enough to feed their three children, aged two, four and eight, who usually stay home alone.
"Where else could I work? I barely know my own name. If you asked me to write my name, I wouldn't know how. Can you imagine? We're like animals here. We don't know anything," Maria told AFP.
They are paid by the day, migrate with the seasons and have no contract, health insurance or pension.
- Powerless to protest -
After the strike in March, employers agreed to a 15 percent raise.
Workers say it isn't nearly enough. Ranchers say they can't afford more.
"Maybe this isn't as fair as it should be, but we don't want to say to the workers, 'Yes, I'll pay you 300 pesos,'" said Luis Rodriguez, who handles public relations for the Los Pinos ranch, the largest in San Quintin.
"What for, if the next day I'm going to send him and his family packing?"
A thousand families live at Los Pinos, a tomato and cucumber ranch, in free housing with communal bathrooms and kitchens.
Their rooms measure less than 10 square meters (110 square feet) and house up to two adults and five children.
Authorities have almost managed to eradicate child labor in San Quintin.
But across Mexico, at least 31 minors aged eight to 17 have died since 2007 while working in the fields, according to rights group Tlachinollan.
It has reported incidents of overseers sexually abusing their workers, as well.
Activists also condemn the stores where many ranches sell their workers' items on credit, allowing them to rack up debts they then struggle to repay.
"It's modern slavery. They're trapped," said Antonieta Barron, an economist at the National Autonomous University of Mexico who has researched day laborers' work conditions.
"They can escape and they won't be chased. But the boss wields that power of employment however he likes, and no one protests."