The answer to 'weed control turning brown' is that this is a common symptom of effective weed control using herbicides. When weeds are sprayed with herbicides, the chemicals work to kill the plants by disrupting their growth processes. This causes the weeds to turn brown and die off over time.
The brown, dying appearance is a good sign that the herbicide is working as intended. However, it's important to be patient and allow the full treatment time for the weeds to completely die and decompose. Depending on the type of weeds and herbicide used, this process can take 1-2 weeks or longer.