Know how to stage growth correctly to make better decisions…
According to the Bible, God prevented the people of Babel from building a tower by mixing up their languages. Once they could no longer understand each other, they couldn’t work together. Likewise, if you can’t speak the same language as your agronomic consultant, it’s tougher to communicate when deciding when to spray weeds or scout for insects and diseases.
Sharp agronomists at Iowa State University in the mid-20th century realized that if soybeans were going to become a serious crop, they would need a “language” to communicate precisely with other agronomists in Missouri, Ohio and elsewhere. The staging system developed for this purpose is still used today.
“When I scout a field, I first determine stage of growth,” says Steve Gauck, a regional agronomy manager for Beck’s, sponsor of Soybean Watch ’24. “If I later find a problem like a disease or insect, it pays to know the stage of growth when looking for possible remedies. Product labels often refer to stage of growth of the crop.”
Staging helps with scouting
Gauck carries a copy of the Purdue University Corn and Soybean Field Guide in his pocket. He refers to it for help when scouting for diseases, insects and weeds, and when determining growth stages.
“When cotyledons are above the surface, that’s the VE stage,” he notes. “Unlike corn, the growing point is above the ground in the VE stage. That’s why hail or frost is less forgiving on young soybeans than young corn.”
Cotyledons expand, and then two unifoliate leaves emerge. “That’s the VC or ‘cotyledons expanded’ stage,” he explains. “Once margins of leaflets making up the first trifoliate no longer touch, it’s the V1 stage.”
The vegetative or V stages progress with theaddition of each set of trifoliate leaves, Gauck says. Tell a farmer anywhere that you are looking at a V6 plant, and he knows it has six trifoliate leaves. “The catch is that the margins of those leaves on that top set of trifoliate leaves can’t touch to count,” Gauck notes.
Source: https://www.farmprogress.com/soybean/how-to-determine-early-growth-stages-in-soybeans