Pennsylvania orchards continue to remain free of plum box virus, according to the latest state survey.
As part of the survey, 61,056 leaf samples from Adams, Cumberland, Franklin and York counties were tested, according to a news release.
The virus, which is harmless to humans but causes deformed or blemished fruit, was first found in Adams County peach trees in 1999.
It is spread by aphids.
The Pennsylvania Department of Agriculture, in conjunction with experts from Penn State, began an eradication program that involved removing all exposed stone fruit trees.
Altogether, 1,675 orchard acres were destroyed.
A quarantine comprising 300 square miles, was imposed.
As part of the eradication effort, the state had to undergo three consecutive years of negative surveys.
Pennsylvania was declared free of plum pox in 2009.
Annual surveys are still required through 2013 as part of the "recovery phase" to ensure the disease doesn't pop up again.
The state has no primary quarantine, although limited areas of Adams and Cumberland counties remain under nursery quarantine regulations.
Read more about plum pox and the eradication program on the Pennsylvania Department of Agriculture's website.