Strange year as drought deepens as the 2017 row crop growing season winds to a close yet corn crop ratings are increasing in an unusual contra-seasonal move while private crop estimates nudge higher, close to the USDA's September estimates.
Using our usual ratings system (where we weight the crop based on the percent in each category and assign that category a factor of 2 for very poor, 4 for poor, 6 for fair, 8 for good, and 10 for excellent and then sum the results) we calculate the week 39 crop ratings which is usually around October 1st for the top 18 corn growing states for this year, last year, 2017 as a percent of the 2016 figure and 2017 as a percent of the 1990-2016 average.
We did this exercise earlier in the year and the results are the same, for while most of the top Midwestern states have crop ratings below 2016 where conditions were among the highest ever and yields record high, this year the core Corn Belt states have lower yields and ratings while the more peripheral states especially in more southern locales are doing better.
KY, NC, OH, PA TN and TX have ratings above last year with Pennsylvania a real standout with ratings 33% above year ago levels.
On the other hand, IL, IA, ND and WI all have week 39 crop ratings in 2017 about 12% below where they stood a year ago.
What explains why the USDA has pegged the current U.S. corn yield at 169.9 bushels per acre which is actually slightly above the 30 year trend is other than South Dakota where the current crop rating of 634 is 13.7% below the 1990-2016 average, the other states that have ratings below average are not so far below such as In down 1.7%, IA off 4.3% MI down 6.7% and ND down 5.0%.
The rest of the states have ratings above their average offsetting lower yields in the other areas.