In northeast and east central South Dakota, we, like most areas, have had an abundance of moisture and many areas had a late planting season, if planted at all. However, all that considered, disease issues in corn have not been too much of a problem.

There is one corn disease that has been noticeable this year that is not normally a problem in our geography, and that is Holcus leaf spot, which is a bacterial disease, caused by the bacteria Pseudomonas syringae. It is very noticeable when entering a field, the leaves will have many small oval or round spots on the leaves, some will have a water-soaked margin around the edge. Later in the season, the lesions will dry and have a papery texture to them.
This disease generally impacts corn early. However, with the late planting season as well as the abundance of moisture and an ideal temperature range of 77-86 degrees, we are noticing it at the current time.

Regardless of how noticeable the disease is, most hybrids have adequate resistance to Holcus leaf spot and no other management practices are needed. Fungicides are not affective since it is a bacterial disease.

Resources and Additional Information

https://extension.umn.edu/corn-pest-management/holcus-spot-corn

https://extension.unl.edu/statewide/burt/holcus-leaf-spot-in-corn/

Download a copy of this technical bulletin here: Holcus leaf spot