Tastier, tougher tomatoes and spinach being developed for South Texas

WESLACO  –  The revival of the once thriving vegetable production industry in South Texas will begin with the development of new tomato and spinach varieties designed to perform well in the area’s harsh conditions, according to a Texas A&M AgriLife Research scientist.

Dr. Carlos Avila, a vegetable breeder at the Texas A&M AgriLife Research and Extension Center at Weslaco, said work has already begun to combine favorable traits from various tomato and spinach cultivars and germplasm.

Research began even before the ribbon-cutting ceremony in October to open Texas A&M AgriLife’s new Rio Grande Valley Vegetable and Education Building.

“In the case of tomatoes, production was nearly wiped out in the Rio Grande Valley by insects and diseases that were not around in the 1960s and 70s when production was thriving here,” Avila said.

Production dropped from 36,000 acres to only about 800 acres today, he said. Texas is now a net importer of about 2.4 billion pounds of tomatoes annually.

John Sharp, Texas A&M University System chancellor, who led the ribbon-cutting ceremony, said, “Being a net importer of vegetables is not only unacceptable, it’s un-Texan.”

Avila said the biggest complaints from consumers are that imported tomatoes just don’t taste as good as they used to.

“That’s because tomatoes shipped to the U.S. from Mexico, for example, have to be picked green in order to extend their shelf life,” he said.

“We just have more pests and diseases here than California and Florida where tomato production has not decreased. High temperatures here also decrease yields. So, a lack of adequate cultivars and cropping practices, plus emerging production areas like Mexico, whose government subsidizes production, has created the need to reestablish production here.”

To develop new tomato varieties that taste better and are resistant to heat, insects and diseases, Avila said he is using both traditional breeding methods and molecular biology to combine favorable traits from several varieties into one.

“We can produce better tomatoes here, not just in taste but in nutritional value,” Avila said. “We can introduce and select for tomatoes with high-content compounds like antioxidants, lycopenes and carotenoids that promote good health and help prevent human diseases.”

Those advantages are not found in imported tomatoes, Avila said, because tomatoes, not necessarily intentionally, are selected for high yields and delayed ripening to extend shelf life.

“So we’re using traditional breeding methods as well as molecular approaches to develop cultivars that are adapted to our area: heat tolerant, resistant to pests and diseases, and cultivars that have enhanced nutritional values.”

In the 1960s, Texas A&M breeder Paul Leeper in Weslaco developed heat-tolerant, high-yielding tomato varieties that performed well in South Texas, but Leeper didn’t have to contend with pests and diseases now rampant in South Texas, including whiteflies that transmit yield-reducing diseases, Avila said.

“That combination of whiteflies transmitting viruses in the early 2000s almost killed off production here.”

Avila is collaborating with Dr. Kevin Crosby, an AgriLife Research vegetable breeder in College Station. The two are working with germplasm and various tomato cultivars from which favorable traits will be used, including Leeper’s lines, those developed by Crosby, and from the Asian Vegetable Research and Development Center headquartered in Taiwan.

To improve cropping systems for growers, Avila is working on evaluating the production of tomatoes under covered structures such as high tunnels.

“In an open field, tomatoes are susceptible to high winds, which reduce their cosmetic value,” he said. “Covered structures can improve quality and yield, reduce pest pressures and extend the growing season into colder temperatures.”

Avila is also working to develop new breeding lines of spinach adapted to South Texas growing conditions.

“Texas is among the top five states in the country producing spinach, but Texas needs varieties that are resistant to white rust and that don’t exhibit late-season bolting to improve yield and quality,” he said.

White rust is a major fungal disease of spinach that leaves rusty white spots on the leaves, making them non-marketable for fresh market sales, Avila said. Bolting, or flowering, is induced by high temperatures, which stops leaf production and affects the taste of spinach.

“Spinach is a winter crop, so selecting for resistance to white rust is difficult because severity of the disease varies from year to year,” he said. “Therefore, we are developing screening methods to consistently select for resistant plants year to year. We are evaluating 500 lines of spinach in Uvalde for resistance to bolting and screening for genes resistant to white rust.”

Avila is also working with germplasm from Arkansas and the U.S. Department of Agriculture’s National Plant Germplasm System.

“Eventually, I want to start a molecular marker program to run DNA tests to determine which varieties are carrying resistant traits that we can incorporate into our lines. Candidate molecular markers linked to white rust are being evaluated with breeders at the University of Arkansas.”

When can growers and consumers expect improved varieties of South Texas tomatoes and spinach?

“I am starting a program basically from ground zero,” Avila said. “It takes at least five years to develop advanced vegetable lines, and another three to test for yield and performance at different locations.

“However, in cooperation with other scientist at Texas A&M AgriLife, we are starting to evaluate advanced breeding lines and cultivars developed in other breeding programs for adaptation to South Texas. Therefore, we expect to start seeing tomatoes produced locally in the supermarkets in a couple of years.”