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). Because of the progress the plants have now made at Chickasha, this update will be our final one for this location. Thirty-one of the 36 wheat varieties have reached or significantly surpassed the 1.5 cm threshold (Table 1). Given the measurements of the five remaining wheat varieties that have not yet reached FHS as of yesterday, I suspect they will reach the threshold by the time we collect our measurements on Monday. 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. 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, 2/28/17, and 3/3/17. 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.