We are collecting corn tar spot samples and we need your help!
Tar spot of corn is a new corn disease first identified in the United States in 2015 in Illinois and Indiana. It has since been confirmed in Iowa, Michigan, Wisconsin, and Florida.
What to look for: Small, black, raised spots (circular or oval) develop on infected plants, and may appear on one or both sides of the leaves, leaf sheaths, and husks. Spots may be found on both healthy (green) and dying (brown) tissue. Often, the black spots are surrounded by a tan or brown halo; this is especially obvious on healthy leaves (see images).
The University of Illinois needs samples of corn infected with tar spot from across the United States as part of a new research project investigating the variability of populations of the corn tar spot pathogen.
We would also like to know if the disease is an issue this year in Indiana and identify the counties where it is present so that we can map the distribution of the disease here in the state.
If you have (or think you have) corn tar spot, please collect several leaves showing the symptoms and send them with a PPDL form https://ag.purdue.edu/btny/ppdl/Documents/Forms/PPDL-Form_13MAY15FILLABLE.pdf. There will be no charge for corn tar spot samples since they are needed for research.
Please wrap the leaves in newspaper and ship in a large envelope. Please ship early in the week. If you are sending samples from multiple locations please label them and provide the date collected, variety of corn, field zip code or county, and previous crop.
Mail to: Plant and Pest Diagnostic Laboratory
LSPS-Room 116, Purdue University
915 W. State Street
West Lafayette, Indiana 47907-2054
Question please contact Darcy Telenko (764-496-5168) or Gail Ruhl (765-494-7071)
