Higher cutting could reduce annual bluegrass contamination in tall fescue seed

Researchers have found that cutting tall fescue at a height of 28 centimeters (11 inches) could potentially reduce contamination from annual bluegrass in seed crops. This is because annual bluegrass seed heads are typically below tall fescue panicles during harvest. In a 2025 trial, harvesting at 28 centimeters resulted in less annual bluegrass contamination compared to cutting at 5 centimeters.

While annual bluegrass was completely absent from the 2024 trial, the 2025 results showed a reduction in contamination when the crop was harvested at the higher height. This suggests that higher cutting could be a useful complement to existing weed management strategies and reduce the need for extensive seed cleaning. The effectiveness of this approach may depend on factors such as crop lodging and the height of the annual bluegrass plants, which can reach up to 40.6 centimeters (16 inches).

The study also found that cutting at a moisture content of 27% (as opposed to 43%) did not reduce tall fescue yield, indicating that lower moisture levels could be an option. However, cutting at 28 centimeters (11 inches) with a combine and lower seed moisture produced more seed than conventional swathing at higher moisture levels.

High swathing may have contributed to reduced yield due to increased seed shattering from higher reel speeds. Further research is needed to optimize cutting height, reel speed, harvest timing, and direct-combining practices to maximize the benefits of this method in managing annual bluegrass contamination in tall fescue seed crops.