Fundamentally Speaking

First Fall Rating of U.S. Winter Wheat

Joel Karlin
By  Joel Karlin , DTN Contributing Analyst

The USDA released its first crop condition report of the year for the 2020 U.S. winter wheat crop with 56% of the crop rated either in the good or excellent categories, compared with 53% last year.

Does this portend a better final winter wheat yield than a year ago?

Not in the least as the correlation between the first winter wheat crop rating in the fall, which is usually furnished the last week of October, and what the final yield will be is actually negative, meaning there is no relationship at all.

This graphic shows the first fall, last fall and first spring rating of the year vs. the percent that the May yield estimate deviated from the 30-year trend of the final yield.

Crop conditions are measured 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.

This year's first fall rating came in at 692 vs. 688 a year ago, right around the ten year average.

The fact is there is a lot of time between now and when the crop is harvested in the June/July period.

From what we have learned over the years is that the crop survives the dormancy period over the winter and what kind of conditions in terms of heat and moisture the plants will have to endure in the spring, especially during the critical reproductive phase are most important for yield determination.

We have seen years where a poor fall rating resulted in very good yields if spring conditions were favorable and conversely years where a high initial crop rating made no difference when winter and spring conditions were poor.

Note that the correlation between the first fall rating and percent yield deviation is poor, improves just slightly for the last fall crop rating, which is usually around the first week of December, but then the correlations really jump for the first spring rating made at the beginning of April.

(KR)

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