Improve disease severity and defoliation estimates

Crop scouts and field researchers often incorrectly estimate the amount of a leaf that is covered by disease lesions, or the amount of defoliation caused by insect pests. To help train people to more accurately estimate disease severity and defoliation, the Crop Protection Network developed this tool. Several common diseases and insect pests of field crops is presented, along with a corresponding visual trainer and self-practice opportunities for assessing injury caused by each disease or insect pest. 

The Crop Protection Network (CPN) is a multi-state and international collaboration of university and provincial extension specialists, and public and private professionals who provide unbiased, research-based information to farmers and agricultural personnel. Our goal is to communicate relevant information that will help professionals identify and manage field crop diseases and other crop production/protection issues.

How to cite this tool

Sisson, A.J., Mueller, D.S., Poss, E., Dear, D. 2020. Disease Severity and Defoliation Training Webtool. Crop Protection Network.


Conception and planning:

Daren Mueller, Iowa State University, and Adam Sisson, Iowa State University

Lesion illustrations:

Emily Poss, Iowa State University, and Adam Sisson, Iowa State University

Website development: 

Setwise Technology, LLC

Contact the Crop Protection Network at