 Hello, my name is Jan Knudel. I'm the Extension Entomologist for North Dakota State University. Today we're out in a local cornfield near Arthur, North Dakota. And we're going to be checking the roots for corn rootworm activity to determine if there's larval activity feeding on the roots of the corn plant by corn rootworm. We need to dig up the corn plants and examine the roots. And another symptom of corn rootworm which is evident in this plant is the goose-necking and the lodging of this corn plant. After we dig up the corn plant root mass, then we can soak the roots in buckets of water and loosen up the soil and then power wash the soil off the roots. And then we can rate them for corn rootworm damage. A common scale for a raiding root injury is a zero to three scale that was developed at Iowa State University with zero being no injury. One, one complete node, approximately ten roots is pruned to within one and a half inch of the stock. Two, two complete nodes, approximately twenty roots are pruned to within one and a half inch of the stock. And three is three complete nodes, approximately thirty roots are pruned to within one and one half inch of the stock. This root raiding scale system is linear and directly related to plant lodging and yield loss. Root injury that exceeds point two five is likely to cause economic loss. You can compare a healthy root mass on the left with the corn rootworm damaged root on the right. If you're observing root injury that exceeds the economic threshold of zero point two five, consider diversifying your corn rootworm management to delay resistance and improve pest management. Examples are crop rotation, planting your refuge, rotating your modes of action with your BT traits and rotation of any soil applied insecticides. Thank you for watching this video and learning more about corn rootworm.