A comprehensive decision tool which allows you to pick your state, county and crop is available at this link (an Excel sheet will load).   This is developed by University of Missouri, The Ohio State University and funded by USDA National Institute of Food and Agriculture and North Central Extension Risk Management Education.

In addition, Iowa State University and Extension has educational events coming up, including a webinar on Friday, Feb 11, and webinars after that date.   The link to register is here.