Organic options

With browntop you need a long-term plan to raise soil fertility, then resow (preferably by drilling) to smother it with more nutritious grass species.

The easiest way to control California thistle is to mow it, preferably just before or while it's raining. It usually takes

3-4 mows to finally deplete the root system, the most common way for the thistle to spread (despite all those seed heads flying about).

Rain helps as it causes fungal infections in the cut stems, which also hasten its death.