It’s that time of year when corn yield estimations increase. The USDA NASS objective yield survey came out on August 17. This report indicates the third highest yield on record (behind 2016 and 2015) at 188 bushels per acre. Moderate to severe drought conditions are undoubtedly the cause for the reduced yields in Iowa this year. It should be expected that there will be large variation in yield within fields but also from one field to the next depending on hybrid selection, date of planting, and field uniformity. Following are some insights into corn yield components and how and when yield components are influenced by crop stresses such as drought.