David Moseley, LSU AgCenter Soybean Specialist

The 2025 soybean planting season in Louisiana began rapidly, with 70%-80% of the projected acres planted by May 1, significantly exceeding the average of 40%-50%. Although most of the crop was planted within the optimal window, heavy rainfall and strong winds have led to issues such as failed stands and delayed weed control applications.

There has also been concern regarding April-planted soybeans in some fields across the state that began to flower at the V3-V4 growth stage. I analyzed data from a planting date trial conducted at the Dean Lee Research and Extension Center in 2021 (Table 1), which included four varieties for each maturity group (MG). For an April planting date, the average growth stage was V5-V7, which aligns with expectations. However, the observed range extended from V3 to V8. Notably, no other planting date by maturity group combination exhibited flowering at the V3-V4 stage, except for those with a June (MG 3.8-4.4 only) or July planting date.

I compared the rainfall events at the Dean Lee Research and Extension Center for April and May in both 2021 and 2025. In 2021, April had 13 days of rain totaling 13 inches, while May had 17 days of rain with 11 inches. In 2025, the Dean Lee Research and Extension Center and the Sweet Potato Research Station had between 7-9 days of rain (4-7 inches) in April and 12-13 days of rain (7-9 inches) in May. The extended number of days and amount of rain could have caused the plants to flower at an earlier vegetative growth stage.

Although some of the MG 4.5-4.9 varieties planted in April flowered earlier in 2021, their average yield was higher than those planted from mid-March and May - July, though not as much as anticipated. Additionally, there was no decrease in percent canopy coverage for the MG 4.5-4.9 and 5.0-5.6 sections planted on April 29. Final plant height also didn't appear to be negatively affected by the earlier entry into the R1 stage.

The observations from this one year of data indicate there is not a strong correlation with flowering at an earlier vegetive stage and final plant height or yield.

Table 1. Data from a planting date x maturity group x variety trial conducted at the Dean Lee Research and Extension Center in 2021.