How to Identify Soybean Development Stages
Remove the soybean plant at ground level to make it easier to stage. Examine each main stem node one at a time to determine the development stage. Focus on the top four nodes that contain fully developed leaves (shown below). A fully developed leaf is one that is located immediately below a node containing a leaf with unrolled or unfolded leaflets (leaflet edges are no longer touching). The soybean crop is considered to be at a particular stage when 50% of the plants reach that stage. Listed with stage description for R1 through R6 are the approximate number of days to R7, or physiological maturity, for full season (FS) soybean planted in May and double crop (DC) soybean planted in June/July.
Days to R7 = 68 FS, 57 DC
Days to R7 = 65 FS, 55 DC
Days to R7 = 53 FS, 47 DC
Days to R7 = 44 FS, 38 DC
Days to R7 = 34 FS, 30 DC
Days to R7 = 19 FS, 17 DC
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July 25, 2019