The Left hates Wal-Mart. Why? Because it’s big, avoids unions and makes a tidy profit. The working poor, among others, love Wal-Mart because it saves them a bundle on food and everything else.

Wal-Mart is also teaching Third World farmers how to grow better food.

Perched on less than an acre of land off an unpaved road in a hardscrabble rural area, farmer Gumercindo Ajanel would hardly seem like a Wal-Mart regular. But in fact, he’s working for the American retail giant.

On a recent morning, he proudly displayed fresh-picked cilantro and parsley he ships to the chain’s local stores. A company agronomist taught him to grow greens that are hygienic and visually appealing. Best of all, he said, Wal-Mart buys frequently and pays promptly. “That helps a lot,” said Ajanel, who employs 30 farmhands in this area about 35 miles northeast of the capital, Guatemala City.

Ajanel, 35, is a rare success story in a nation where nearly three-quarters of the population is rural and largely poor, yet being squeezed by modern economic forces. Supermarkets are rapidly displacing informal channels through which peasants traditionally sold their harvests. Growers used to hawking dusty potatoes out of the back of a truck are finding shoppers defecting to chains whose produce is clean, uniform in size and often lower in price.

Okay: cleaner, cheaper and better food. Must be something wrong, right?

Consumers are thrilled at the savings and convenience. But the trend worries some agricultural economists and development experts. Now simply growing a good crop is not enough to ensure the survival of many small-scale farms; they must get their products onto supermarket shelves.

Consumers = everybody who eats.

In Guatemala, Wal-Mart this week unveiled a program aimed at linking more mom-and-pop growers to its supply chain. In partnership with the U.S. Agency for International Development and two nonprofit groups, the company plans to train 600 farmers over the next three years to supply produce for its local stores.

It’s good public relations for Wal-Mart, but company officials say it also helps the bottom line. Most of the fruits and vegetables the retailer sells in its 457 Central American stores are produced locally. But supply glitches have resulted in temporary shortages of products such as lettuce.

Wal-Mart wants to diversify its supplier base to keep its shelves stocked as it expands. It’s also looking to give small farmers a crack at producing niche items such as herbs that big growers can’t be bothered with and that are too expensive to import.

“It helps us ensure a supply of specialties,” said Ignacio Perez Lizaur, chief executive of Wal-Mart Centroamerica. “It does, ultimately, make business sense.”

The success or failure of this and similar efforts may determine whether thousands of farm families can remain on the land or join the millions who have migrated to urban slums or to rich nations such as the United States.

Good business means good things.

To meet those high expectations, retailers such as Wal-Mart are requiring suppliers worldwide to meet stringent quality standards that dictate details such as the type of seed and post-harvest handling. It’s no easy feat for large producers, much less peasant farmers with little capital or formal education.

To help bridge the knowledge gap, Wal-Mart has 40 agronomists on staff in Central America who work closely with growers such as Fermin Pec, who cultivates radishes, lettuce, cabbage and other vegetables on about 75 acres in San Pedro Sacatepequez.

“Their pickiness has helped me improve,” said Pec, who employs 100 people and has been supplying supermarkets in Guatemala since 1990.