What’s soybean stage R2 versus R4 and why does it matter? Turns out, it matters a whole lot, as does knowing how long you can anticipate the crop being in each stage. Soybeans move through three growth stages: vegetative, when weed control is the priority, to reproductive, when disease control is likely most timely, and then moves on filling/ripening, when stress could really eat into yields (as could insects). Within each stage is an incremental advancement — from counting trifoliates, to delineating R-stages (R for reproductive) from R1 and up.
To clear up any confusion, Dr. David Hooker, with the University of Guelph and Horst Bohner, Ontario Ministry of Agriculture, Food and Rural Affairs, explain how to distinguish when the crop moves from one crop stage to another. Included in this Soybean School episode is a discussion on optimal timing of a fungicide application, plus at what stages top nodes vs. the bottom/middle of the plant matters more and a reminder on when to count trifoliate leaves.
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