July 8, 2022
Understanding grain sorghum growth stages helps aid in pest management for the crop which can help maintain yield potential. There are ten different identifiable stages of growth (Table 1). Days after emergence are approximated because growing conditions and maturity play a key factor in growth and development rates.1
Table 1: Identifying characteristics and approximate time intervals between sorghum growth stages.
Stage 0: Emergence of the plant from the soil.
Stage 1: The third leaf on the plant has a true collar. The coleoptile leaf is the first leaf and has a rounded tip while true leaves have a pointed tip.
Stage 2: The collar of the 5th leaf is visible.
Stage 3: Growing point differentiation. The total number of leaves has been determined. Leaves continue to emerge from the whorl as the plant is transitioning to reproductive growth.
Stage 4: Flag Leaf. The last leaf in the whorl is the flag leaf. The flag leaf is smaller in size than the other leaves.
Stage 5: Boot. The head has formed in the flag leaf, and the peduncle is elongating.
Stage 6: Half Bloom. The head emerges from the flag leaf and flowers halfway. Flowering starts from the top of the panicle.
Stage 7: Soft Dough. Grain formation occurs during Stage 7 and can be marked by kernels that are in the soft dough stage.
Figure 1. Sorghum kernels at soft dough stage.
Stage 8: Hard Dough. The kernels transition to hard dough and obtain their final color.
Figure 2. Sorghum kernels at hard dough stage of growth. Tiller with soft dough kernels showing behind mature sorghum head.
Stage 9: Physiological Maturity: A visible dark spot forms on the kernel. The grain is typically between 25 to 40% moisture content.1
Figure 3. Infographic representing the growth stages of grain sorghum.
Properly identifying the growth stage is critical prior to applying a crop protection product. Crop protection labels, such as herbicide labels, provide growth stage information for safe application. This may also be combined with a maximum height of the crop. Application of a crop protection product outside of a specified growth stage can potentially harm the plant and can result in injury during reproductive development.2 Yield potential can be further reduced by competition if weeds are not managed.
Correct growth stage identification may play a role when controlling insects, disease, or applying a desiccant. Many crop protection labels have a pre harvest interval indicating the amount of time that needs to pass prior to harvesting the crop.3 It is imperative that label restrictions are followed. If you are unsure of the label directions, please contact your Bayer or crop protection representative.
For additional information on grain sorghum growth stages, please see Channel® Agronomy Advice, Sorghum Growth Stages.
Sources:
1Vanderlip, R.L. 1993. How a sorghum plant develops. Kansas State University. S-3 http://www.bookstore.ksre.ksu.edu
2Weed Control Strategies in Grain Sorghum. 2018. Kansas State University. https://enewsletters.k-state.edu/harveycounty/2017/05/25/weed-control-strategies-in-grain-sorghum/
3Reay-Jones, Francis P.F. 2017. Grain Sorghum Insect Control. Clemson University. South Carolina Pest Management Handbook for Field Crops – 2017. https://www.clemson.edu/extension/agronomy/pestmanagement17/insect%20control%20grain%20sorghum.pdf
Web sources verified 5/9/22.
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ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.
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