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). Wheat progress towards FHS is now beginning to advance quickly within our plots at the Chickasha location. Fifteen of the 36 wheat varieties (42%) have reached FHS, and more will be reaching the 1.5 cm threshold in the next few days. As a reminder, these measurements were collected from plots under simulated grazing. Grazing delays FHS, which is why we recommend checking plants from a non-grazed area of the field (e.g., just outside the hotwire). This helps provide time for finalizing plans to remove the cattle as the grazed area reaches FHS. For example, our border plots of Ruby Lee, sown at the same time, were at FHS during our last data collection (2/22); whereas, within the plots, Ruby Lee just reached FHS (1.6 cm) during our data collection yesterday (Table 1). Keep in mind that several factors in addition to grazing influence the onset of FHS. These include the wheat variety, location, temperature, available moisture, and planting date (later sown wheat will typically reach FHS later). The 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, we cannot stress enough the importance of checking for FHS on a field-by-field basis.
Table 1. First hollow stem (FHS) results by variety collected from simulated grazed plots at Chickasha on 2/16/17, 2/22/17, and 2/28/17. Plots were sown on 9/15/16. The threshold target for FHS is 1.5 cm (5/8” or the diameter of a dime). The amount of hollow stem for each variety represents the average of ten measurements. Varieties that have reached FHS are highlighted in red.