Allegan County has been hit hard by a tree root disease that the Michigan Department of Natural Resources says is "one of the most economically damaging forest diseases in the northern hemisphere."

The Michigan DNR's new Forest Health Highlights report says that Heterobasidion root disease (HRD) was first reported in southern Michigan in 1963. It has since been found in 18 counties in the Lower Peninsula and one county in the Upper Peninsula.

Most infections start on freshly cut stumps. The infection then spreads to the roots where it spreads to other trees connected to those roots. When an infection is found, the DNR considers trees within five miles to be at a higher risk for infection. Red, white and jack pine trees are the most susceptible to the disease which is very difficult to eliminate.

Allegan County has one of the highest concentrations of the HRD in Michigan. An interactive map from the Michigan DNR shows where the disease has been confirmed in Michigan and how far the five-mile advisory zone reaches.

Michigan DNR

The map also includes links to photos to help identify HRD and a place to report a suspected infected.

The video below explains the "circles of death" and also demonstrates keys to identification.