Death comes to us all. Life's but a walking shadow | It has been known for some time that the USDA (specifically the WAOB) uses a weather adjusted yield prediction equation, developed by Westcott & Jewison that includes a mid-May crop progress term. The term uses the mid-May crop progress of each of 8 major corn producing states weighed by their respective harvested acres and results in factor of 0.29 for every weighted average point above the mean. You can read about it here:https://www.usda.gov/oce/forum/presentations/Westcott_Jewison.pdf. That 0.29 factor is about 1/10 of the factors for July temperature & July precip. squared and 1/50 of the factors for July precip. and June precip, shortfall.
In short, there has to very significant planting delays to seriously affect yield. |