Best Herbicide For Mulched Areas?

[chuckrox8]

My backyard has about 3,000 sq ft zoysia and is mostly surrounded by pine bark mulch. The mulched area is probably 75ft x 30ft. I put down a pretty thick layer last year, ~4-5", and all sorts of weeds are growing through the mulch without an issue. Other than just spraying the entire area with RoundUp is there a better post-emergent herbicide I should be using to eliminate and prevent the weeds?

Thanks

[g-man]

1) have you removed the old mulch and replace it with new?

2) have you identified the weeds?

[Dchall_San_Antonio]

People use mulch to control weeds, because weeds cannot get a strong rooting in mulch. You should be able to pluck the weeds out easily. Or I use a stirrup hoe to drag the weeds out without disturbing the mulch very much.