While another round of weather extremes is bearing down on soybean fields as mid-August gets underway, growers still have opportunities to protect 2026 yield potential, according to Missy Bauer.
Bauer, Farm Journal Field Agronomist and co-owner of B & M Crop Consulting in Coldwater, Mich., says the focus now should be on the soybean yield components growers can still influence: number of seeds per pod and seed weight.
“If I’m really trying to push my soybean yields, I need to think about these yield components,” Bauer told AgriTalk host Chip Flory on Thursday.
Soybean yield is developed based on these components:
- Number of pods per plant
- Number of beans per pod
- Seed size or weight
At this point in the season, pod number is largely established — primarily because genetics plays a major role. But management and growing conditions can still influence seed development and final seed size.
Seed Size Could Be The Swing Factor This Season
Bauer says seed size deserves particular attention because it can make a major difference in final yield.
“That seed size all of a sudden can swing bean yields 15 bushels one way or the other,” she says.
In her area, south-central Michigan, Bauer says farmers have experienced three consecutive falls with difficult seed-fill conditions that ultimately reduced yields.
Heavy rain raises concerns about Sulfur Availability
Too much rainfall across some eastern Corn Belt states this month is creating another late-season concern: nutrient loss, particularly sulfur.
“Sulfur is a big deal when we go to fill out these seeds, making sure we have enough nutrition in that plant to fill what we have,” she says.
Sulfur is mobile in the soil and can leach below the root zone during excessive rainfall, with the risk particularly high on sandy soils.
While Bauer emphasizes that late-season soybean management isn’t about relying on a single input or practice, growers still have several opportunities to protect seed fill and final yield potential.
Here are six late-season soybean considerations for farmers to evaluate:
1. Determine whether sulfur is actually needed
A late-season sulfur application might help, but only when a genuine deficiency exists.
Purdue Extension research indicates foliar sulfate-S has corrected in-season soybean sulfur deficiencies at V4, R3 and R5. In those trials, about 3 lb. of SO₄-S per acre performed best. An R5 application may have value when a deficiency is confirmed, while higher rates caused leaf burn.
2. Protect the upper canopy from foliar disease
Keep scouting for diseases that can reduce green leaf area during seed fill. Foliar fungicides can reduce diseases such as frogeye leaf spot when applied at later reproductive stages. However, treatment decisions should be based on disease risk, variety susceptibility and local recommendations, advises the Crop Protection Network.
3. Keep scouting for insects
Soybean aphids and other pests deserve attention, particularly during R5 and into early R6. Extension recommendations call for continued soybean aphid scouting through these stages, although the potential for yield loss declines as the crop approaches full seed.
4. Look for pod and stem diseases
Pod and stem blight, for example, can cause infected seeds to crack, shrivel and become moldy. Oklahoma State University Extension reports that foliar fungicide applications during R5-R6 can improve seed quality from pod and stem blight in years characterized by warm weather and frequent rainfall.
5. Don’t spray foliar fertilizer just to keep soybeans green
Late-season foliar nutrition has sometimes been promoted as a way to delay senescence and improve seed size. But research does not consistently support that strategy.
Iowa State University reports numerous trials have produced inconsistent results, including some yield decreases. More recent research indicates a low probability of a yield increase from late-season foliar fertilization.
Bauer To Address Soybeans at Yield Academy
Bauer will expand on these themes at the Farm Journal Yield Academy in Rochester, Minn., next week during the final day of the 2026 Pro Farmer Crop Tour.
She will walk growers through a systems approach to soybean yield components and discuss where late-season management can make the biggest contribution.
Growers can learn more about the program and register at farmjournalyieldacademy.com. When prompted for a coupon code, AgriTalk’s Chip Flory adds that growers can enter “agri” for an available discount.
