NAPLES, Fla. — University of Florida tomato breeders are working to develop varieties that can be mechanically harvested, helping growers address labor costs and availability.

Although breeder Sam Hutton, who’s based at the Gulf Coast Research and Education Center, Wimauma, is excited about prototypes, he said researchers are at least a few years away from releasing commercial varieties.

He updated the industry on breeding efforts at the Joint Tomato Conference, Sept. 4, in Naples.

For growers such as Tony DiMare, vice president of Homestead-based DiMare Fresh Inc., these varieties can’t come soon enough.

“The biggest concerns we have and why we are looking at mechanization is the current labor situation and the lack thereof,” he said. “And that obviously carries a heavy cost, direct costs and indirect costs, such as workers comp, transportation and a whole slew. It’s become a labor supply concern more so than the direct costs of labor.”

The average cost to plant, grow and harvest an acre of fresh-market tomatoes in Florida is $15,000, said Monica Ozores-Hampton, an assistant professor and vegetable specialist at the Southwest Florida Research and Education Center, Immokalee. Of that, about 55% is just for labor, which includes staking, tying and pruning plants, and harvesting.

Tomato breeders seek machine-harvestable varietiesIn Florida, tomatoes are grown on plastic-covered beds into which wooden or metal stakes have been driven. During the growing season, workers create trellises of string between the stakes and train the plants up, pruning them when necessary.

After harvest, workers must remove the stakes before the field can be prepared for the next crop. In the Homestead area, growers rely on metal stakes, which are even more difficult to remove than wooden ones used elsewhere, DiMare said.

Hutton is working to develop low-growing fresh-market tomato varieties, which set fruit that ripens during a short window. The bush-like plants wouldn’t require staking or training, either.

In California, processing tomato growers rely exclusively on machines to harvest their crop.

But crossing those varieties with fresh-market ones suited to Florida isn’t practical because the two types are so different, Hutton said.

“The difference is they’re picking red tomatoes — we’re going after mature greens,” he said. “They’re growing plums and we’re growing large-fruited tomatoes. There’s a major distinction. It’s much more difficult to work with a large fruited tomato than a plum.”

Breeders want a tomato with a jointless pedicel, meaning the fruit separates cleanly from the plant without a stem attached that could puncture other fruit going up a harvester conveyor.

Varieties also have to produce good yields and have good flavor.

Hutton said he thought he had some contenders last season after two trials produced promising results. But last season’s wet, cold weather promoted rough-looking, misshapen fruit that would not have been unmarketable.

“I can’t underscore the difficulty of working with this type of tomato,” Hutton said. “It was really discouraging coming out of this spring’s trials.”

But the tough conditions also yielded some other promising prototypes that warrant additional trials, he said.

The breeding effort is being funded by a U.S. Department of Agriculture Specialty Crop Research Initiative grant that runs through the 2014-15 season. In addition to Hutton, Bielinski Santos, an assistant horticulture professor, and tomato breeder Jay Scott are involved in the project.