IDAHO FALLS, Idaho — The USDA’s Animal and Plant Health Inspection Service recently deregulated 2,279 acres of eastern Idaho farm land that had been included in its pale cyst nematode program due to association’s with infested fields.
PCN Program Director Tina Gresham said changes to the regulated area were posted Dec. 6, and testing is underway that may clear several hundred more associated acres for deregulation in January.
To be deregulated, fields with associations to quarantined fields, such as use of a common piece of equipment, must undergo a series of soil surveys following two potato crops, with negative results.
Growers who operate in associated fields have to sanitize all equipment that leaves those fields, using a pressure washer to remove soil. Both growers and receivers of their potatoes must have permits through Gresham’s office. They must undergo USDA inspections so the agency can learn how the parties handle waste, tare dirt and cleaning water.
Tare dirt – the excess dirt hauled away with harvested crops – must be buried in a nonagricultural area or landfill. In the Shelley, Idaho, area, Gresham said most tare dirt from associated fields fills a reclaimed gravel pit designated for the purpose.
The recent update brings the total acreage in the program to 8,474 associated acres and 21 fields with a combined 2,300 infested acres.
Most of the recently deregulated associated fields were added to the program in 2011, Gresham said.
“Over time, we’ve deregulated several thousand acres of associated fields. The size of our deregulated area is dynamic, whether we’re detecting new associated fields or able to clear (fields),” Gresham said.
PCN, a microscopic parasite that can reduce potato yields by 80 percent, was first detected in east Idaho tare dirt samples in 2006. Infested fields have all been found within a roughly 5-square-mile radius of Bingham and Bonneville counties. APHIS has set a goal of eradicating PCN, hoping to allay fears of trade partners. In Fiscal Year 2013, APHIS invested $4.1 million in the Idaho PCN program.
Gresham said the program may deregulate its first infested acres in the spring, when several fields are scheduled to complete a process known as bioassay. APHIS takes soil samples from infested fields following nematode treatments and applies a stain that turns dead nematodes purple. When no living nematodes are detected through staining, fields enter bioassay, which entails placing cysts from soil samples with potato plants in a greenhouse in Moscow, Idaho, to stimulate hatching. After fields successfully complete bioassay, a requirement is lifted for growers to steam farming equipment used in an infested field before moving it to a new field. Pressure washing remains mandatory until infested fields are fully deregulated by producing four potato crops following bioassay that prove to be clean in APHIS field surveys.