This update outlines the results of five years of trials exploring pre-desiccant options for managing bulky white clover crops, aiming to reduce rapid leaf regrowth following diquat desiccation under wet or high-fertility conditions. Achieving effective desiccation required balancing this process with post-harvest regrowth, as clover seed crops are often used for lamb grazing on New Zealand cropping farms.
Key points
- Growers rely on diquat (Reglone®, Group 22) as a white clover desiccant, but when crop biomass is high, e.g. in wetter seasons, regrowth can collapse the canopy and reduce seed yield.
- Herbicides glufosinate-ammonium, glyphosate, tribenuron, and clopyralid were also as effective as MCPA as pre-desiccants prior to diquat application.
- However, these herbicides also reduced post-harvest regrowth by between 46 to 99 %, compromising post-harvest grazing.
- Seed germination was not affected by any desiccants.