Pretty sure they are like lantana( pest) , so your doing the same work as prison day release . Like lantana , I think , you have to take it out from the roots . Otherwise your just making it bushier for the next trip. Taking a few out by the roots ( if I see lantana, anywhere while fishing , fossicking, I always rip some of these nastys out by the roots. They come out quite easily ) you can feel good about yourself to when you don't find much . Even better that you've cleared a spot for easy access for someone else to come find gems at your favourite , now cleared location .
Just turn the plant up so the roots dry , and doesn't start again.
