Matt from Austin, Tx writes
I recently spent a small fortune to have my front and back yards professionally landscaped. Less than 2 months later, there are already a lot of weeds (might actually be St. Augustine grass from old yard) invading parts of my rocked areas even though weed barrier cloth had been laid beneath the rocks. The odd thing is that the weeds (St. Augustine?) only seem to be a problem in some areas of rock and almost non-existent in other areas. I don't know for sure, but I think the landscapers might have used some of the contaminated soil from the old St. Augustine yard to fill-in a few low-lying areas before installing the rock (crushed limestone). I think this because the weeds (or St. Augustine) are only growing in these previously low-lying areas. My new lawn is Zoysia although I haven't noticed much if any weeds (or St. Augustine) growing in those areas. I have clumping bamboo in the yard as well. I need a solution that will kill the St. Augustine without harming my clumping bamboo or my Zoysia grass. The bamboo will likely come into direct contact with the herbicide whereas the Zoysia will likely only receive a small amount of overspray.
There are not specific products labeled to kill St. Augustine grass in zoysia, however many folks will either spot treat with a non-selective herbicide, or they will use a product that is labeled as safe for zoysia but not for St. Augustine. A good non-selective choice for spot treating would be RoundUp QuikPro. To spot treat with a selective herbicide, you could something with quinclorac, such as Image Kills Crabgrass or QuinKill Max Crabgrass and Weed Killer. You will need to use a surfactant such as the Hi-Yield Spreader Sticker with QuinKill Max. Quinclorac will not damage bamboo. The RoundUp QuikPro may damage young bamboo plants.
Answer last updated on: 06/15/2016
