The 2021 U.S. spring wheat crop already rated as one of the worst ever continues to suffer under relentless heat and limited rainfall.
It was interesting to note that North Dakota corn, soybean and spring wheat ratings went down last week even though this state probably had the best rains of any in the Corn Belt and this shows just how dry soils are.
This chart shows U.S. spring wheat ratings as of the middle of June (week 23) and end of July (week 30) on the left-hand axis vs. the percent that July and final yields deviate from 1986-2020 trend of final yields on the right-hand axis.
We use 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 week 23 rating at 608 is really the second worst ever since the USDA started tabulating spring wheat conditions in 1986.
Only the horrific drought year of 1988 was worse with a week 23 rating of 468 that actually fell more over the next seven weeks, so by the time week 30 occurred at the end of July in 1988, the rating was the lowest ever at 400.
The third-worst rating was actually just four years ago in 2017 with the middle of June rating of 650 that fell to 542 by the end of July.
We also focus in on 2002 as a week 23 rating of 714 that fell to 606 by the end of July; we also note 1989 where the week 23 rating of 766 fell to 588 by week 30 and 2006 where the week 23 rating of 732 fell to 570 by week 30.
We should note that both 1989 and 2006 showed some of the biggest seven week deterioration over the past 35 years but on average crop ratings fall by 37 points from the middle of June to the end of July with the largest increase ever just 46 points in 1992.
This seems to cast doubt on any prospects for significant improvement in this year's spring wheat crop given that crop conditions usually decline from mid-June to the end of July and any improvement in crop conditions would appear to be modest.
As for the impact of these low crop ratings on yields, first off note that the correlation between the week 23 ratings and the percent that the July USDA yield forecast deviates from trend is 68%; that increases to just 71% using the week 30 ratings and the percent that final yields deviate from trend.
1988 had July yields 32% below trend and 35% below for final yields, 2002 had July yields 15% below trend and 23% below for final yields, 2006 had July yields 18% below trend and 17% below for final yields while 2017 had July yields 12% below trend and 11% below for final yields.
Only 1989 saw just modest yield declines of 5% below trend.
No doubt 2021 U.S. spring wheat yields will be below trend, so the question is by how much?
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