Will WASDE Yield Projections for Corn and Soybeans See Serious Reductions?

The World Agricultural Supply and Demand Estimates (WASDE) report, issued monthly by the U.S. Department of Agriculture (USDA), serves as a critical benchmark for global commodity markets. It provides updated forecasts on crop production, yields, supply, demand, and ending stocks for major U.S. and world commodities. The upcoming September 2025 edition, scheduled for release on September 12, comes at a pivotal time as harvest progresses across the U.S. Midwest. Traders, farmers, and analysts are closely watching for potential adjustments to yield projections for corn and soybeans, particularly in light of mounting disease pressures and variable weather conditions. Any significant reductions could reshape market dynamics, potentially reversing recent price declines driven by abundant supply expectations.

Recap: August’s Suspiciously High Projections and Market Fallout

The August 2025 WASDE report delivered a shock to the markets with yield estimates that many viewed as overly optimistic, if not suspiciously high, given on-the-ground reports. For corn, the USDA pegged the national average yield at a record 188.8 bushels per acre (bpa), up 7.8 bpa from July and well above the average trade guess of around 181 bpa. This translated to a massive production forecast of 16.7 billion bushels, also a potential record. Soybean yields were raised to 53.6 bpa, up 1.1 bpa from July, but production was trimmed slightly to 4.3 billion bushels due to a 2.4 million-acre reduction in harvested area.

Private firm StoneX had contributed to the pre-report buzz with its own elevated estimates, forecasting corn yields around 186-188 bpa in late July, emphasizing favorable early conditions but warning of August weather risks. When the USDA’s numbers exceeded even these bullish views, markets reacted sharply. Corn futures plummeted, with prices dropping to multi-year lows as the prospect of a supply glut overwhelmed demand signals. Soybean prices, however, reversed early losses and rallied modestly, as the net production cut was seen as mildly bullish despite the higher yield. Overall, the report reinforced bearish sentiment, with corn ending stocks ballooning and soybean exports projected lower amid trade tensions with China.

Critics labeled the projections “suspiciously high” because they relied heavily on farmer surveys conducted in early August, before late-season stressors fully materialized. As one analyst noted, the lack of weather threats at the time may have inflated responses, but emerging issues could force downward revisions.

Current Pressures: Disease and Weather Weigh on Crops

Since the August report, reports from the field have painted a more challenging picture for the 2025 corn and soybean crops. Disease outbreaks and inconsistent weather patterns across the U.S. Midwest—the heart of American grain production—have raised concerns about yield potential.

Disease Challenges

• Corn: Southern rust has emerged as a major threat, particularly in Iowa and southern Minnesota, where it has slashed yields by 25 to 50 bpa in affected fields. Tar spot, another fungal disease, continues to pressure crops in the region, exacerbated by earlier humid conditions. Agronomists report that these issues, combined with other foliar diseases, could lead to widespread reductions if not contained.
• Soybeans: White mold leads the pack as the dominant disease this year, with sudden death syndrome (SDS) and frogeye leaf spot on the rise. Heat and humidity in July fueled an early surge in foliar and stem diseases across the Midwest, prompting experts to urge intensive scouting and fungicide applications. In states like Indiana, root rots and iron deficiency chlorosis have added to the stress.

These diseases thrive in variable moisture environments, and late-summer weather will be decisive. As one extension specialist put it, “September weather and disease pressure will ultimately decide the story of the 2025 harvest.”

Weather Impacts

Weather has been a double-edged sword. Excessive rainfall in parts of the Midwest earlier in the season fueled disease proliferation and caused localized flooding, leading to yield concerns in Illinois and Nebraska. More recently, dry conditions have gripped the eastern Corn Belt, with drought affecting 4% more corn acres in the past week alone. The latest USDA Crop Progress report as of September 7 shows corn conditions at 68% good-to-excellent (down 2% from the prior week) and soybeans at 64% (down 4%), still above historical averages but signaling potential vulnerability.

Early frost risks in drier areas could further trim yields, while the western Midwest has seen wetter patterns that might support better finishes. Crop tours, such as Pro Farmer’s, have reported mixed results: lower pod counts in Nebraska (down 23% year-over-year) but stronger performances in South Dakota. Some farmers report pollination issues reducing whole-field yields by up to one-third.

Expectations for September WASDE: A Case for Reductions?

Analysts anticipate modest downward adjustments in the September report, shifting from farmer surveys to more objective models incorporating weather data and early harvest results.

Sources: Trade surveys, StoneX, S&P Global. Pro Farmer’s tour pegged corn at a much lower 182.7 bpa, suggesting room for surprises if disease impacts are underestimated. Historical trends support cuts: Over the past decade, soybean yields have dropped an average of 2% from August to September, potentially trimming to 52.6 bpa.Vegetation health maps and crop ratings hint at yields potentially higher in some models (corn up to 194 bpa, soy 55 bpa), but field-level disease and dryness may override these. If reductions materialize—say, 1-2 bpa for soybeans and 2-5 bpa for corn—it could shave 80-200 million bushels off production forecasts.

Potential Impacts on Commodity Markets

A serious yield reduction would be bullish for prices, tightening projected supplies and boosting ending stocks estimates. Corn futures, currently hovering near $4 per bushel, could rally toward $4.50 if production falls below 16.5 billion bushels, supported by steady ethanol demand (over 1.07 million barrels per day) and robust exports. Soybeans, teetering around $10 per bushel, face downside risks below that level without cuts, but a lower yield could spark a rebound to $11, especially if Chinese demand improves or Brazil’s crop faces delays.

Conversely, if the USDA maintains or raises estimates, markets could tank further, exacerbating farmer margins amid high input costs. Global factors, including Brazil’s expanding soybean acreage and abundant Black Sea wheat, add downward pressure, but U.S. yield surprises remain the wildcard.

As harvest ramps up, with 4% of corn already in by September 7, the September WASDE could either confirm the August optimism or deliver a reality check.