Halosulfuron Injury on Onion
In 2006, onion plants were submitted to the lab with distortion and proliferation of the bulbs and above ground growth. The symptoms were characteristic of injury from ALS-inhibiting herbicides. We learned that halosulfuron (Permit) was used in 2004 for yellow nutsedge control in corn, the field was fallow in 2005 and then onions planted in 2006.
Halosulfuron is degraded in the soil by microbes and hydrolysis and carries an 18-month rotation restriction to onions. While 18 months had clearly passed before onions were planted, microbial degradation can be significantly slowed in soils that remain saturated. Because of this, we believed halosulfuron carryover was a possibility because the injured onions were growing in muck soil that remained wet for much of the year. Therefore, the onion soil was tested and halosulfuron was detected at 0.28 ppm.