Holcus spot

Pseudomonas syringae

Corn leaf with a holcus spot lesion
Corn leaf with a holcus spot lesion.
Holcus spot is a relatively minor bacterial disease of corn. It infects corn leaves which have already been damaged by heavy rain, wind, or hail.
Holcus spot produces small circular lesions on leaves which are initially dark green but then become white or tan with a yellow halo.
Holcus spot does not typically affect yield because of its limited spread and the fact that it is most common in young corn. However, in severe cases on corn later than V6 it may cause some yield loss.
There are no control methods available for holcus spot since it is a bacterial disease. Crop rotation and tillage may reduce the likelihood of infection in subsequent years.