(April 15, 11:30 a.m.) REEDLEY, Calif. — That peaches, plums and nectarines are good sources of vitamin C — and other beneficial vitamins and minerals — has never been a secret in the offices of the California Tree Fruit Agreement, Reedley.

That the stone fruit could be the perfect summer replacement for the vitamin C-rich winter navel oranges — that is, before the Southern Hemisphere’s summer citrus onslaught — was no secret either. The unsolved mystery at the Tree Fruit Agreement is why it had not spread the word to consumers, specifically mothers, in the past.

It was during a brainstorming session that the Summer C campaign was born, said Joanna Frith, the agreement’s domestic market manager.

“Vitamin C is more easily recognized by consumers than antioxidants and other such benefits,” she said.

Spreading the word to consumers has moved digital. The agreement’s generic stone fruit banner advertisements will appear on six Web sites: allrecipes.com, foodnetwork.com, rachaelray.com, family.com, familyfun.com and recipezaar.com. Those Web sites specifically target mothers and children, Frith said. The online advertising campaign will run from June 1 through Sept. 15.

“It will deliver 25 million estimated media impressions,” Frith said. “That’s 25 million consumers.”

The tree fruit agreement’s rotating banner advertisements will appear in top performing areas of the Web sites, Frith said, and will also appear in those areas or pages of the Web sites that focus on recipes, healthy living and healthy eating.

Extending the reach to health-conscious consumers, the Summer C banners will be the main sponsor for newsletters from allrecipes.com.

“The newsletters are sent to opt-in subscribers who are already interested in healthy living and new recipe ideas,” Frith said.

Yet another branch of the digital campaign on allrecipes.com is the integration of 20 peach, plum and nectarine recipes on the Web site’s own recipe database, she said. Each of the stone fruit recipes will include a photograph and link to the Summer C microsite on the tree fruit agreement’s own Web site, www.eastcaliforniafruit.com.

“The more education consumers have about the fruit and how to select it, the more likely they will make successful purchases,” Frith said.

The campaign is reinforced by Summer C point-of-purchase materials, available for downloading on the tree fruit agreement’s Web site by retailers promoting California peaches, plums and nectarines.

Embedded in all of the Web site advertising messages are two new phrases, “fresh from the tree,” and “fresh for me.”

The tree fruit agreement is spreading the word to retailers this season via a two-pronged effort, Frith said. The staff will not limit its marketing efforts to produce managers, as it has in past years. It will be working closely with the advertising departments of retail chains and independent stores.

The tree fruit agreement will continue to offer radio commercials in 60-second and 30-second versions, each of which ends with a five-second music bed to permit retailers to customize the messages with store identification. The commercials may be used on radio stations or on in-store audio systems, Frith said. The commercials are downloadable from the tree fruit agreement’s Web site.