Chemical Weed Control in German Chamomile

I have planted about 5 hectares of German Chamomile. I have a problem with broad leafed weeds in amongst my chamomile. What can I use as a herbicide to get rid of the weeds, but that will not harm the chamomile?

Afalon (active ingredient linuron) has been used on chamomile. It is both a pre-emergent and post-emergent herbicide. Monosan has also been used, but Afalon was better in a six year study (https://www.actahort.org/books/249/249_6.htm).