Fungicide sprays for Asian soybean rust (ASR) are closely tied to soybean growth and development. The following links on soybean growth and development are excerpted from the United Soybean Board Interactive Soybean Guide (www.psu.missouri.edu/soydoc). Click on each of the stages for helpful photographs.
Determining a growth stage:
Two diagrams, originally intended for ASR scouts, are also useful for identifying soybean growth stages. Michigan State University Extension has prepared a diagram depicting soybean bloom, pod and seed development, and maturity stages (111k PDF). In addition, the following graphic from the University of Nebraska-Lincoln depicts plants in V4 and R1 stages, clearly showing four fully expanded trifoliate leaves at V4, and flower buds (at each node) at R1.
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