AMES, Iowa — As any gardener knows, healthy plants come from healthy seeds. Free from pathogens, healthy seeds are a prerequisite for sustainable agriculture and food systems. Best practices when crops are in the ground are meant to protect seeds from exposure to pests and diseases, but there are many ways by which seeds can be infected by disease-causing organisms. These organisms may be carried with, on, or in seeds and, under suitable environmental conditions, may be transmitted to cause disease in developing seedlings.
“New pathogens and pests emerge on a regular but unpredictable basis,” explains Gary Munkvold, Iowa State University (ISU) plant pathologist. “It is very challenging to design proactive actions to prevent and detect contaminated seeds and to understand the risks associated with seed-borne diseases.”
So how do we manage and significantly reduce overall pest risk?
The National Seed Health System (NSHS) was set in motion in August 2001 to do just that. Authorized by USDA’s Animal and Plant Health Inspection Service and administered by ISU’s Seed Science Center (SSC), NSHS serves to accredit private and public seed labs to carry out seed health testing, field inspections, and seed sampling necessary for them to be eligible to receive phytosanitary certificates.
A phytosanitary certificate, critical to the international movement of seeds, is a declaration that seeds are healthy. The certificate acts like a passport, signifying that seeds have been duly inspected and eligible to be moved across national borders.
“One of our key concerns in ensuring seed health is establishing the best methods to use when testing,” adds Munkvold who is also co-director of the NSHS. “We continue to develop pathogen detection methods that are more and more sensitive, but it requires detailed risk analysis to interpret the results and assess the potential impact of each seed-borne organism,” he continues. “What’s needed is better research into the epidemiology of diseases.”
The NSHS also provides scientific expertise to establish standardized seed health test methods and phytosanitary inspection procedures. This is done through a peer review process that involves a panel of seed experts. Along with good lab practices, these standardized tests minimize erroneous results, reduce product liability for exporters, and prevent imports from being rejected. These methods also are harmonized with those of international groups such as the International Seed Testing Association so that seed authorities anywhere in the world can use them to detect seedborne pathogens.
“When a problem appears in one country, its impacts can quickly reverberate around the world,” Munkvold adds. “This can easily become an obstacle to trade that can affect the supply of seeds and the development of new crop varieties that farmers need.”
Standardized testing methods as well as improved phytosanitary regulations have prevented global seed pandemics and placed healthy seeds in the hands of farmers.
“Access to quality healthy seeds is the cornerstone of global food security,” says Manjit Misra, director of the SSC. “On it depends our ability to feed, clothe, fuel, and nourish the globe. For farmers to feed a world population expected to grow to 10 billion by 2050, they must make sure every seed planted counts. When you start with healthy seeds, you get healthy plants and good yield, which leads to more food to keep the population healthy,” Misra continues. “Thus, to feed the world, we must first seed the world.”
For the past two decades, the NSHS has proven its ability to safeguard seed health, a critical standard in international seed trade. Seeds for planting represent tremendous value to the U.S. agricultural economy. In 2018 the United States exported $1.085 billion worth of these seeds and imported $997 million worth of them. The commercial value of global seed exports has more than tripled since the inception of the NSHS.
“The NSHS has improved the conduct of seed trade in significant ways. For example, good seeds used to languish in the docks of ports until the importing country gets the chance to test them. Now, a phytosanitary certificate attached to the shipment tells importing countries that it is safe to let the seeds through” explains Charles Block, who also co-directs the NSHS.
Aside from commercial trade, seeds are shipped to different parts of world for crop research and development, to multiply seed stocks, and for other purposes. In addition, shifts in pest and pathogen distribution brought about by climate change have made the task of protecting and promoting seed health more complicated. To offset these challenges, seed producers are paying more attention to seed health management throughout the production and distribution chains.
Over the past 20 years, the NSHS, operated by Iowa State, has made strides in the urgent and increasingly more complex task of protecting seeds from diseases. It is, in more ways than one, “the CDC for seeds.”
–Seed Science Center
National Seed Health Center
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