First Hollow Stem Update – 2/26/2021

Amanda de Oliveira Silva, Small Grains Extension Specialist

First hollow stem (FHS) is the optimal time to remove cattle from wheat pasture. This occurs when there is 1.5 cm (5/8” or the diameter of dime) of stem below the developing grain head (full explanation). To give you a point of reference, the average FHS date over the past 20 years at Stillwater is March 6.

The latest FHS results from our forage trials in Chickasha (Table 1) and Stillwater (Table 2) are listed below. A few more wheat varieties in Stillwater have reached or passed the 1.5 cm threshold.

The Mesonet First Hollow Stem Advisor and the updates we provide give an indication of the FHS stem conditions in a particular area. However, because of the number of factors that can influence when FHS occurs, it is extremely important to check for FHS on a field-by-field basis

Table 1. First hollow stem (FHS) results for each variety collected at Chickasha. Plots were planted on 09/29/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

Table 2. First hollow stem (FHS) results for each variety collected at Stillwater. Plots were planted on 09/21/2020. The threshold target for FHS is 1.5 cm (5/8″ or the diameter of a dime). The value of hollow stem for each variety represents the average of ten measurements from non-grazed plots. Varieties that have reached FHS are highlighted in red.

Similar to previous years, we will monitor occurrence of FHS in our wheat plots at Stillwater and Chickasha and report the findings on this blog.

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About Amanda De Oliveira Silva

I joined Oklahoma State University in 2019 as an Assistant Professor and Small Grains Extension Specialist and was promoted to Associate Professor in 2025. My program integrates applied research and Extension with the goal of improving the productivity, profitability, and sustainability of wheat production systems. While much of my work is rooted in Oklahoma and the Southern Great Plains, the questions I study—how agronomic management, crop physiology, and plant nutrition interact to influence yield, grain quality, and nutrient use efficiency—are relevant to wheat-growing systems around the world. By working closely with producers, industry partners, and researchers, my goal is to develop practical, science-based solutions that help growers navigate production challenges and improve the resilience of their farming systems.

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