Key Points
- Only one of 10 experiments gave a significant seed yield response to mechanical topping of white clover seed crops.
- There was a trend for topping to increase seed yield as the amount of dry matter removed increased above 2000kg DM/ha (when topping at 70mm height at first flower) with heavier soils tending to be associated with seed yield increases.
- Soil characteristics (and possibly location, temperature) influenced the response to topping.
- The application of 2,4-D Ester suppressed seed yields when applied at 2 and 3l/ha in July at four sites in the 2007/08 season. Late season herbicides (applied at first flower) showed variable results but did not enhance seed yield.
- Moddus applied at first flower reduced seed yield.