By Alex Yost, YieldPoint Program Specialist
Deep below the snow and ice covering our fields this winter lives a pest commonly overlooked in agronomic management. The root lesion nematode (RLN) is a pest of over 400 crops and plants native to Wisconsin. The management issue with root lesion nematodes is the damage caused. The damage of a root lesion nematode is primarily diagnosed as being fungal or bacterial rots when seen on crops in season. RLN is a parasitic nematode meaning that it cannot kill it’s host plant or it will die itself. This means the nematode feeds on root cells, and when the cell dies it moves to the next, and so forth. Each wound caused by the feeding is then infected with rots and bacteria after the nematodes move on. In extreme cases damage can equate to death of the plant and field conditions similar to in the picture. Death to plants specifically correlated to nematode feeding is rare on crops after seedling stage, but yield penalties do occur further in the growing season.
At a recent conference in Madison I had the privilege to sit in on a presentation from Dr. Ann MacGuidwin, the nematode specialist for the University of Wisconsin-Madison. She spoke of the severity of RLN and other nematodes in Wisconsin fields, (needle nematodes, root knot nematodes, and soybean cyst nematodes). For the University of Madison 90% of all nematode tests that came in to the lab contained some number of RLN leading to further research into the severity on agronomic crops. Dr. MacGuidwin stated there was minimal data producing a threshold for treatment of RLN in-season but sufficient data can be drawn on pre-plant nematode testing in Wisconsin due to our winters reducing populations to a static number of nematodes in the soil. Contact your agronomist or myself for further information on nematode management, or if you feel like you have a nematode problem in your fields.