Tar Spot of Corn Web Book

Tar Spot of Corn Preface and Introduction

CPN 2015. Published March 16, 2021. DOI: doi.org/10.31274/cpn-20201214-2

Darcy Telenko, Purdue University; Martin Chilvers, Michigan State University; Nathan Kleczewski, University of Illinois; Daren Mueller, Iowa State University; Diane Plewa, University of Illinois; Alison Robertson, Iowa State University; Damon Smith, University of Wisconsin; Adam Sisson, Iowa State University; Albert Tenuta, Ontario Ministry of Agriculture, Food and Rural Affairs; and Kiersten Wise, University of Kentucky.

Tar spot of corn is a new and emerging disease in the Midwestern United States. This disease caused by Phyllachora maydis, was first identified in Illinois and Indiana in 2015. As of 2021, tar spot has now been confirmed in fourteen states, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, Nebraska, New York, Ohio, Pennsylvania, Wisconsin. It has also been reported in Ontario, Canada.

Significant yield impact was first noted in 2018 in Illinois, Indiana, Michigan and Wisconsin, with yield losses ranging from 20 to 60 bushels per acre in regions experiencing the epidemic. 

Tar spot has become an annual problem in regions with favorable environmental conditions which include moderate temperatures and high relative humidity or moisture availability. 

Characteristic tar spot symptoms on corn foliar tissue.

Live Tar Spot Distribution Map from the Corn ipmPIPE

For current tar spot updates:

Download theTarspotter app, a tar spot forecasting managment tool for iOS and Android.

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Use the Table of Contents on this page to navigate between chapters and resources available as part of this text. 

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