Although there's no evidence the phomopsis organism is pathogenic to spinach, the American Seed Trade Association is taking no chances—it is funding Washington State University research to determine the organism's risk, according to an industry newsletter.
The phomopsis organisms belong to a genus containing species that cause disease on other plants, such as soybeans and sunflowers.
As a result, the U.S. Department of Agriculture's Animal and Plant Health Inspection Service is treating the organism as a quarantine pest until its risk is determined.
The Alexandria, Va.-based ASTA is funding a research project led by research seed pathologist Lindsey DuToit of Washington State University to determine the organism's pathogenicity and evaluate seed treatments.
In 2011, the U.S. Customs and Border Protection and APHIS officials rejected a large shipment of spinach seed because of the fungal disease, according to a news release.
Each time a lot is rejected, APHIS scientists collect samples and sequence the DNA. They then compare the sequences to those in the U.S. collection, the largest in the world.
The sequence from the 2011 interception didn't match anything in the collection, meaning it was not represented in the collection or was an entirely new species.
This year at least 10 more shipments have been rejected because of the organism. Most are produced and imported from the Netherlands and Denmark.
Comparison of the DNA sequences matched isolates from Europe. They were an asexual form of Diaphorthe (Phomopsis) viticola, which is pathogenic on grapevines and blueberries.
Each seed shipment is valued at $750,000 to more than $1 million. The spinach seed market has an annual value of $12 million to $20 million, according to the newsletter.
Spinach is grown nearly year-round, mostly on the West Coast in California and Washington.