b'methods, Jones explains, adding thatOne example of this problem is ISTA methods are validated in interlabo- the Tomato Brown Rugose Fruit Virus ratory tests in collaboration with both(ToBRFV), which was first reported in official governmental laboratories andlate 2019 in production fields and green-seed company laboratories. houses in many countries, such as Mexico, The Seed Health Committee (SHC) ofGermany, U.S., the Netherlands and Italy.ISTA has defined guidelines for validationAs a new disease, there are now over of methods based on the study of perfor- 25 countries regulating for it, using a mance criteria. potpourri of molecular seed health testing The SHC is currently harmonizing andmethods, Dunkle says. validating five seed health methods forThe North American Plant Protection vegetable and field crops, Jones says. Organization (NAPPO) set to work evalu- Ric Dunkle. Steve Jones.ating several of those methods. Standardized Equals Success Each country will run each of those Ric Dunkle, senior director of Seed Healthtesting methods and compare the results and Trade at the American Seed Tradeto figure out which one or two will be the Association (ASTA), explains why non- most consistent and then recommend standardized testing is a real problem. those to the rest of the world, Dunkle says.If the seed is tested using one methodISHI-Veg has also identified 6 valida-before export in one country, and thention criteria against which the perfor-tested using a different method on importmance of the methods is measured.in another country, they may get different results. It creates a lot of uncertainly toTesting Trialsmove those seeds around, Dunkle says.ISHI-Veg have outlined best practices for In some cases, seed may be tested fivePCR, ELISA and dilution-plating assaysGary P Munkvold. Rose Souza-or more times while en route to its finalused in routine seed health testing, withRichards.destination. best practices in preparation. 20/ SEEDWORLD.COMJUNE 2021'