The United States is now free of the plum pox virus, according to the U.S. Department of Agriculture.

USDA Under Secretary for Marketing and Regulatory Programs Greg Ibach made the announcement Oct. 17.

“Today, our 20-year fight against plum pox disease is officially over,” Ibach said in a statement. “Working with our partners, we’ve eliminated this disease and protected the United States’ $6.3 billion stone fruit industry.”

Plum pox was first detected in Pennsylvania in 1999. It was found in Michigan and New York in 2006. The disease impacts stone fruit such as plums, peaches and almonds. It does not kill infected trees outright but causes severe yield losses and greatly reduces fruit marketability.

The virus spreads over short distances by aphids and over long distances via the movement of infected nursery stock or by grafting infected buds onto healthy trees, according to USDA.

No other countries have successfully eradicated plum pox. The eradication program was a cooperative effort among USDA’s Animal and Plant Health Inspection Service (APHIS) and Agricultural Research Service, state departments of agriculture, the Tuscarora Nation, industry, academia, growers, and homeowners.

The program included collecting and testing plant samples, removing diseased and suspect trees, using plum pox virus-tolerant plants, and temporarily banning the planting of susceptible stone fruit varieties, according to USDA.

The program eradicated the disease from Pennsylvania and Michigan in 2009, and from Western New York in 2012. By the end of 2018, program partners had completed three consecutive years of stone fruit field surveys in Eastern New York — the last remaining quarantined area in the United States — with no further detections, according to USDA.

APHIS’ continuing efforts to safeguard against plum pox include ongoing monitoring for the disease in stone fruit-producing states, science-based import regulations to prevent its reentry via imported nursery stock and propagative material, and continued cooperation with Canada to help prevent incursions from that country, according to USDA.