URBANA, Ill. — Last week USDA released its first national corn condition rating of the season. The crop, as you’ll hear, wasn’t in great shape. While it doesn’t mean much at this time of year, Todd Gleason reports there is a relationship between the first crop condition rating and the end of the season yield.
The weekly Crop Progress report is mostly the work of Extension and FSA employees, at the least the data collection part. They report local crop conditions to state USDA offices, mostly on Monday morning, who in-turn tally those numbers and pass them along to Washington, D.C. for compilation and release on Monday afternoon. Work at the [University of Illinois](http://farmdocdaily.illinois.edu/2017/06/how-to-use-within-season-crop-condition-ratings.html) shows a strong relationship between the end-of-season crop condition ratings and crop yield, however, agricultural economist Scott Irwin says that doesn’t hold so well for the rest of the season.
Irwin: But, of course, what you really want to know is how soon do they become really predictive of final yields. Our analysis says they become pretty useful about mid-July for corn and not until about mid-August in soybeans.
The first corn rating of the season, released just after Memorial Day, wasn’t good. the crop had been cold and wet. It showed up, or in this case didn’t show up, in the good and excellent categories USDA NASS uses. Those are the two grades the U of I economist say correlate. The math works like this; the first corn condition rating was 65% good or excellent, minus 8 points for the average drop to the end of the season rating, which brings you to 57%.
Irwin: And then you plug that into the relationship we presented in the article and you end up with 164.3, basically on that set of calculations. It is an intriguing and pretty low number. Clearly that is not where the market is at and it is just one model, one exercise. Certainly, it is something to keep your eye on.
If you do, in about mid-July you can use the math in the farmdocDaily article to forward calculate the national average yield for corn; mid-August for soybean.[read blog post](http://farmdocdaily.
— Scott Irwin, Agricultural Economist – University of Illinois and Todd E. Gleason, Farm Broadcaster
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