How UH helped save Hawai'i's papayas
By Andrew Hashimoto
Picture Hawai'i without papayas. Breakfasts lose their tropical flavor. Crates vanish from shipping docks. More than 200 farms disappear.
Advertiser library photo November 2001
The papaya ringspot virus, spread by diseased plants, nearly wiped out the Big Island's crop, valued at $16 million.
Advertiser library photo November 2001
For generations, the papaya ringspot virus, or PRSV, threatened the livelihood of Hawai'i's papaya farmers. It was discovered on O'ahu in the 1940s and devastated papaya production. By the mid-1980s, more than 90 percent of the state's papayas were grown in the Big Island's Puna district.
The removal of infected trees in neighboring areas kept Puna virus-free for decades, but time was not on the growers' side.
Knowing that Puna's luck wouldn't last forever, researchers from UH-Manoa's College of Tropical Agriculture and Human Resources, Cornell University, the U.S. Department of Agriculture and private industry began work to develop a papaya genetically engineered to resist the virus.
They thought that if a papaya made one of the proteins from the virus, it might be immune to PRSV, just as vaccines made of proteins from viruses or bacteria trigger human defenses against diseases.
They were on the right track.
In May 1992, PRSV invaded Puna. By late 1994, nearly half of the district's papaya fields were infected, and farmers were going out of business. The research team raced against the virus as papaya yields collapsed: Between 1992 and 1998, the Big Island's papaya harvest shrank by 50 percent, and yields per acre dropped 35 percent.
Meanwhile, the transgenic "Rainbow" papaya underwent years of rigorous testing. Three federal agencies USDA's Animal and Plant Health Inspection Service, the Environmental Protection Agency and the Food and Drug Administration all concluded the "Rainbow" papaya was safe, wholesome and had the same nutritional value as other papayas.
"Rainbow" seeds were given free to the state's struggling papaya farmers in May 1998, six years after PRSV first hit Puna. "Rainbow" fruit went on the market the following year.
By 2001, Puna was producing 40 million pounds of papaya, up more than 50 percent from 1998. Today, "Rainbow" papaya makes up more than 50 percent of the state's papaya acreage.
If "Rainbow" had not been introduced, there would be no papaya industry on the Big Island. The virus-free acres planted in "Rainbow" create a buffer that slows the spread of PRSV to susceptible plants and allows farmers to grow nontransgenic (or non-GM, not genetically modified) varieties such as "Kapoho."
Today, growers in Puna can produce non-GM fruit for markets that want it, including Japan, which does not accept GM papaya.
Transgenic papaya is deregulated, and all tests have judged it safe to eat. While pollination of non-GM papaya trees by GM papaya pollen does not pose a health or safety risk, we recognize that it is a concern for organic growers who define their produce as 100 percent GM-free.
It's important to note, however, that papaya farmers will not lose their organic certification because their non-GM trees have been cross-pollinated by GM pollen, producing papayas that have no GM flesh but do contain some GM seeds.
Under USDA regulations, fruit from non-GM papaya that has been cross-pollinated by GM pollen can be sold as organic if the grower can document that, except for the cross-pollination, the crop was grown according to organic standards and that every effort was made to avoid cross-pollination.
Our college has helped growers of GM and non-GM papayas develop procedures that enable both kinds of farming operations to coexist.
The College of Tropical Agriculture and Human Resources is working to ensure the quality of UH papaya seeds. The recent report that some of our non-GM papaya seeds may have resulted from cross-pollination is a concern because we want the contents of UH seed packets to match their labels.
Data provided by Genetic ID, a commercial laboratory that analyzed seed and leaf samples for GMO-Free Kaua'i/Hawai'i Genetic Engineering Action Network, indicate that a very small fraction of the UH "Waimanalo" seeds tested (about 0.2 percent) resulted from cross-pollination by GM pollen. This is a very low level of cross-pollination for commercial papaya, and recent studies of "Waimanalo" seed failed to detect any GM seed.
We are committed to producing high-quality seeds for Hawai'i's farmers and gardeners and will continue to monitor seed production to ensure that.
The University of Hawai'i supports the coexistence of all forms of agriculture. We try to find approaches that best meet farmers' needs, whether through conventional cultivation, integrated pest management, organic production or genetic engineering.
We strongly believe that conventional agriculture, organic farming and biotechnology can coexist, and transgenic papaya is a fine example of this.
Andrew Hashimoto is dean of the College of Tropical Agriculture and Human Resources at the University of Hawai'i-Manoa.