Wheat Disease Update – 08 June 2016

This article is written by Dr. Bob Hunger, Extension Wheat Pathologist.
Department of Entomology & Plant Pathology – 127 Noble Research Center
Oklahoma State University – Stillwater, OK
405-744-9958 (work) – bob.hunger@okstate.edu
I thought last week was my final update, but over the last week I have received a couple reports of “dark” wheat appearing in wheat fields in Oklahoma such as the one below from near Cordell, OK (Washita County).  This condition, which is known as sooty mold, results from various fungal molds growing on the dead plant matter in the wheat heads.  Sooty mold typically appears when wheat that is turned cannot be cut in a timely manner.  It also seems to be more prevalent where wheat received less than optimum fertility, freeze occurred, or something else resulted in less vibrant plants.  Wet weather, high humidity, and late harvest then provide an ideal climate for secondary fungi to colonize the dead tissue causing the sooty appearance to the wheat.  Typically the sooty mold occurs in areas of a field where moisture and/or humidity is highest.  Test weight and yield can both be affected, but often the biggest problem with sooty mold is that it will result in black point of wheat kernels (photo below).  With time, sooty mold fungi colonize (typically) the germ end of the wheat kernel giving the kernel a black point.  Often such wheat grain has reduced viability, and use of heavily black-pointed wheat as seed wheat should be avoided.  Typically there are no actions to take to prevent sooty mold/black point other than to try to harvest wheat as quickly as possible once the wheat has turned.
Sooty mold in wheat field – Andy Evans         Wheat head with sooty mold
Black point of wheat kernels (bottom row of wheat kernels)