Special-needs label retains PCN program’s best tool
By John O’Connell
IDAHO FALLS, Idaho — Eastern Idaho’s pale cyst nematode eradication program has deregulated more acres and resolved a fumigation dilemma, according to a recent update by Tina Gresham, PCN program coordinator with the USDA’s Animal and Plant Health Inspection Service.
APHIS announced on Jan. 10 that 2,297 more acres managed with special sanitation requirements due to associations with infested fields have been deregulated. That news follows a Dec. 6 announcement of the deregulation of 2,279 acres of associated fields. The changes reduce the total regulated area to 8,478 acres, including 2,300 infested acres.
PCN, a microscopic parasite that can reduce potato yields by 80 percent, was first detected in east Idaho 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 to protect trade.
As the program heads into another season, Gresham said it’s key weapon in battling PCN, methyl bromide, will remain a viable option thanks to an effort led by the California contractor hired to apply the chemical, Tritical, Inc.
New Phase II labeling standards took effect last season governing methyl bromide, and requiring applicators to adhere to broad buffer zones to protect surrounding residences. Gresham said the buffer zones, which varied based on field conditions and applications methods, could be as wide as 1,000 feet in some cases and would have made methyl bromide treatments unfeasible. The program had enough carry-over chemical last season to treat field borders under the old label, reserving new chemical for the centers.
Fumigation typically starts in the third week of April and is completed within 10 days to a month, depending on weather. Gresham said under Phase II standards, fumigation would take all summer, driving up costs and preventing growers from planting commercial grain crops following treatments.
For the upcoming season, Tritical obtained a special-needs permit allowing the program to continue with just 25-foot buffers. Gresham explained the methyl bromide Phase II label modeled Florida weather conditions. Tritical hired the same modeling expert who calculated the Phase II label to run Idaho weather data, finding much smaller buffers would suffice.
Gresham said obtaining the special-needs label required months of work by Tritical, APHIS, the Idaho Potato Commission, the Idaho State Department of Agriculture and EPA. Though she’s encouraged by the results in the short term, she acknowledged there’s a global push to phase out methyl bromide.
One promising alternative is litchi tomato, a plant that stimulates hatching of cysts but doesn’t offer a viable host, leaving PCN to starve. Gresham said growers are eager to expand litchi tomato field trials this season based on positive 2013 data. Research by University of Idaho Extension weed scientist Pam Hutchinson shows litchi tomato roots grow as deep as 5 feet, reaching cysts missed by methyl bromide.
Louise-Marie Dandurand, UI’s PCN project director, recently publicized data showing litchi tomato prevented PCN reproduction and reduced cysts in a greenhouse setting, and the combination of litchi tomato and methyl bromide in the field was more effective than methyl bromide alone.