According to USDA data, the US corn harvest remains in its very early stages, with just 7% complete as of September 15. Typically, market participants begin to gain a clearer picture of the national crop situation at this stage, helping shape market direction in the weeks ahead. This year, however, the outlook remains uncertain. Traders expect yield forecasts could soon be revised lower, even as the USDA has unexpectedly raised its estimates for planted and harvested area. Market participants are monitoring closely to assess how these changes could affect global supply.  

On yields, traders noted that the USDA made an unexpected move in its August 12 WASDE report, raising the 2025/2026 forecast to 11.85 mt/ha, a month-on-month increase of 0.49 mt/ha. Sources linked the revision to favorable weather and optimism following crop tours such as Pro Farmer, though concerns persisted around southern rust outbreaks and pollination issues. 

By September, market sources told Expana that the USDA’s forecasts appeared overly optimistic. In its September 12 WASDE update, yields were cut to 11.72 mt/ha. While still above the 2024/2025 figure of 11.26 mt/ha, traders cautioned that the final outcome for 2025/2026 could fall below September’s pro  jection, with uncertainty remaining high. 

Market participants said yields have been pressured by southern rust disease and pollination issues, which may have been key in driving the recent rally on CME corn futures. Prices were up 7.43% week-on-week at $167.96/mt as of Thursday’s market close, September 18. Analysts warned that recent rains could accelerate the disease’s spread, with untreated fields in some cases facing yield losses of up to 45%. Reports suggest the Midwest, particularly the Ohio and Mississippi river valleys, has been hardest hit. 

A market participant told Expana “there are no words to describe how bad some corn fields are looking right now.” 

Adding to the uncertainty, traders noted that the USDA’s September 15 WASDE report raised total production expectations by 1.8 million mt (0.4%), despite the lower yield forecast. The increase was attributed to a larger harvested area, up 549,000 ha to 36.4 million ha. Traders said this was unexpected, marking the largest acreage increase for this timeframe since records began in 1990. Since June, total planted area has expanded by 1.42 million ha, with analysts suggesting favorable conditions may have encouraged more corn to be seeded. 

Looking ahead, sources believe clarity will emerge as harvesting advances, with the main question being whether acreage gains can offset yield losses and disease pressure. Some traders said further yield deterioration could provide price support, though optimism around overall supply could limit upside. Demand is also seen as a key driver, with the USDA forecasting US corn exports at 75 million mt, up 2.5 million mt from last month.