Potato Grower

26 POTATO GROWER | MAY 2020 YOUR OFF-ROAD TRACTION EXPERTS Out Performs All Wheel Drive at a Price Your Company Will Value. The Airdown System comes with a 2-year warranty and costs less than our compe tors—making it the best value on the market today! Contact Us To Learn More 1-877-MAD-TIRE 6 2 3 - 8 4 7 3 6 2 3 - 8 4 7 3 www.AirDownYourTires.com We Keep Your Trucks From Ge ng Stuck. 4074-18AirDown12h.indd 1 2/3/20 3:36 PM YOUR OFF-ROAD TRACTION EXPERTS Out Performs All Wheel Drive at a Price Your Company Will Value. The Airdown System comes with a 2-year warranty and costs less than our compe tors—making it the best value on the market today! Contact Us To Learn More 1-877-MAD-TIRE 6 2 3 - 8 4 7 3 6 2 3 - 8 4 7 3 www.AirDownYourTires.com We Keep Your Trucks From Ge ng Stuck. 4074-18AirDown12h.indd 1 2/3/20 3:36 PM FLATTENING THE CURVE It is critical that we continue to train field pathologists, inspectors and crop advisors with classical skills in plant pathology. Is the U.S. potato industry capable of responding to a novel disease of potatoes? Montana Seed Potato Certification Program By Nina Zidack Director At the time of this writing, the U.S. is in its first week of active mass response to the novel coronavirus pandemic. The seminal question that arose at the beginning of the epidemic was: Is our nation prepared to respond with high-throughput testing? Timely and accurate identification of any pathogen is paramount to our ability to isolate infected individuals and protect the healthy. This brings up the question of readiness in the potato industry to respond to a novel pathogen. Do we have the capability of identifying a novel pathogen? Would we be able to develop tests for detection and implement them in a high-throughput manner? USDA-APHIS Plant Protection and Quarantine is responsible for protecting our crops from foreign pathogens through phytosanitary restrictions on movement of specific plant materials. They also possess the expertise and capability to identify novel pathogens through a technology called next-generation sequencing. This is the same technology that was used to identify the novel coronavirus. Once the genetic makeup of a pathogen is elucidated, PCR assays can be developed rapidly to detect the new pathogen. If a novel pathogen were to appear in our potato crops, we would rely on experienced field pathologists and field inspectors to recognize the first signs and symptoms of an unusual disease. It is critical that we continue to train field pathologists, inspectors and crop advisors with classical skills in plant pathology. I am heartened that in recent years, we have seen a resurgence in new candidates who have spent some time with one foot in the furrow. Once a new pathogen has been identified, certification agencies would have to ramp up quickly to respond with high-throughput testing to assess the distribution of the new pest. Our capability for high-throughput testing varies significantly across seed potato certification programs, but through the acquisition of equipment and training, capabilities can ramp up very quickly. Many seed potato certification programs across the U.S. are already employing high-throughput testing for bacterial and viral pathogens. An example of rapid implementation of PCR testing is Idaho's response to an outbreak of bacterial ring rot. Through transfer of techniques and knowledge developed at North Dakota State University, the Idaho Crop Improvement Association (ICIA) acquired the ability to perform this testing in 2014. After harvest of the 2014 crop, they processed 575,600 tubers and performed nearly 3,000 PCR tests. In addition, ICIA was able to test equipment and storages on infested farms and to identify the potential for all potato handling equipment to harbor BRR. It was determined that loaders, pilers, harvesters and even-flows were especially likely to be infested, even after disinfection. No Idaho seed lot has tested positive for BRR since the 2016 crop. Another example of rapid implementation of PCR testing for a bacterial pathogen was the national response to the Dickeya dianthicola outbreak that started in 2015. This outbreak was a little more complicated because Dickeya and Pectobacterium cause similar symptoms, and multiple Dickeya species exist that can infect potato. Dickeya also has a much more variable genome than the pathogen that causes BRR, which makes development of detection tools complicated. Within the first 18 months of the outbreak, we learned which of the available detection methods worked with D. dianthicola strains in the U.S. We also found a new D. dianthicola strain that, to date, has only been reported in the U.S., and developed two PCR assays for it. Fortunately, development of pathogen detection assays, even for pathogens with highly variable genomes like D. dianthicola, has become much simpler due to bioinformatics tools that allow swift comparisons of genome sequences. At the height of the outbreak, up to 20 percent of seed lots in some regions were reported to have this pathogen. Routine testing of seed lots has greatly reduced the impact of this pathogen. In Montana, we began using PCR to detect PVY in tubers in 2013. We used the technique as an add-on service to growers if they wanted to collect more information on the virus status of particular seed lots after the post-harvest test. From 2013 to 2017, we tested an average of 12,000 tubers per season. With the development of more efficient techniques, we incorporated PCR as an optional test for duplicate samples of G1 and G2 seed lots. In 2018 and 2019, the number of tubers tested by PCR rose to about 50,000, with 125 seed lots being tested in each of those years. We consider the PCR assay for

• Cover