ST. PAUL, Minn. (AP) _ Foresters and landowners are concerned that a disease that kills oak trees is spreading farther north in Minnesota.

The mighty oak is one of the most abundant trees in Minnesota. Oak wilt was been around for decades and has been confirmed in 40 Minnesota counties.

But, the Minnesota Department of Natural Resources is now finding cases farther north than ever before. It was recently discovered in Crow Wing County.

The non-native disease slowly kills the leaves of an oak tree and, eventually, the tree itself. It spreads through its root systems, sap beetles and through open tree pores.

People accelerate the spread when they prune oaks and carry infected firewood across the state.

More From AM 1240 WJON