Soybean progress and pod set growth stages

By Dr. Laura Lindsey, Adapted from C.O.R.N. 2022-23

Currently, most soybean fields in Ohio are at the R3 growth stage, meaning there is a pod at least 3/16 inch long (but less than 3/4 inch long) at one of the four uppermost nodes on the main stem with a fully developed leaf. Some late planted fields may still be at the flowering growth stage while some early planted fields may be entering the R4 growth stage (pod 3/4 inch long at one of the four uppermost nodes on the main stem with a fully developed leaf).

Soybean R3 Growth Stage

What does the soybean crop need to maximize yield during pod set? The number of pods per acre sets the maximum number of seeds per acre, which is the component most strongly related to final yield. Therefore, pod development becomes one of the most critical stages in the life of soybean. While stress at this time will result in aborted pods, seed number per pod and seed size may compensate for loss of pods. The R3-R4 growth stage is an important time to scout your fields for diseases, insects, and nutrient deficiencies and apply fungicide, insecticide, and foliar fertilizer if conditions warrant an application.

Misconceptions at the R3-R4 growth stage: There are several common misconceptions about soybean plants at the pod set stages.

Misconception:

The soybean plant needs to retain most of its pods to maximize yield.

Reality:

Pod abortion occurs naturally and allows the soybean plant to adapt to current environmental conditions. Many pods will still abort under stress-free conditions.

Misconception:

Presence of 4 and 5 bean pods is required for high yields.

Reality:

Pod number and seed size affect yield more than seeds per pod.

Misconception:

Light needs to penetrate the whole canopy.

Reality:

Complete canopy closure by this stage is important to capture all available sunlight, retain soil moisture, and reduce weed competition.

Misconception:

Making a sprayer trip across the field will either be beneficial or neutral.

Reality:

Tire traffic at this stage can lead to yield declines.

Misconception:

Foliar fertilizers will be beneficial to provide nutrients to pods and will impact yield.

Reality:

Data from across the U.S., shows no yield benefit to foliar fertilizer application at the R3 in the absence of a visual nutrient deficiency.

Misconception:

Late season nitrogen application will provide a positive return on investment.

Reality:

Data from across the U.S., shows no consistent economic benefit to late-season nitrogen fertilizer application.

For more information on soybean pod set, see this Science for Success video: https://www.youtube.com/watch?v=ThlgsQ4lOiQ and also this Science for Success FactSheet: https://soybeanresearchinfo.com/wp-content/uploads/2022/01/Science-for-Success-Soybean-Growth-Stages-V3.pdf

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