Soody – posted 01 May 2003 18:20
How do I kill the bermuda in my St. Augustine without killing my St. Augustine?
Thank you in advance for the help.
Brad – posted 03 May 2003 08:01
Here in Tallahassee, FL I had the same problem with Centipede grass and I used a chemical by the name of Vantage. Mixed with water and applied via back pack sprayer, it worked exactly as advertised in that it killed all the Bermuda without harming the Centipede. I don’t know if it works on St. Augustine but I think Centipede and St. Augustine have very similar characteristics. Obviously you need to research this before you apply the Vantage. I wasn’t able to find it at Home Depot, Lowe’s or any nursery so I had to buy it over the phone from a company in Pensacola , FL which shipped it to me. You can do an internet search on “Vantage Weed Killer” and find the company as well as some info about Vantage. I think the company was something like Pest Pro but I’m not certain. Good luck.
seed – posted 03 May 2003 15:08
WARNING. Vantage kills most grasses including St. Augustinegrass. The only grasses that can be safely treated with Vantage (chemical name sethoxydim) are centipedegrass and the fine fescues such as creeping red fescue.
A while back there was considerable research by Dr. Bert McCarty at the University of Florida (currently at Clemson University) on Prograss (chemical name ethofumesate) for selective control or suppression of bermudagrass in St. Augustinegrass. Prograss is a professional product available to commercial pest control applicators. The protocol that he developed involved three split applications, the first two in mixture with atrazine, and all applied during the “spring greenup” for the bermuda. For whatever reason, this did not catch on in Florida. It may have been that anything short of 100% control of bermuda is going to allow the bermuda to regrow throughout the year. Also, it could have been that it was a tough protocol to follow.Phil
Dchall_San_Antonio – posted 28 June 2003 01:22
Just set your mower to the highest setting and the bermuda will die out from too much shade. You’ll like the St Aug when it’s tall. You’ll still have to cut it weekly.
Your water will last longer with the grass tall, too. There are a couple of reasons for this. One is that tall grass supports deeper roots. Deeper roots have more water available to them when the water is in the deeper reaches of the soil.
The second reason is more biotechnical. The grass blades have stomata on them to transpire CO2, oxygen, and water vapor. They open in the morning and close when they get their fill of CO2. If the plant has more stomata exposed (like from taller grass), then the stomata collect CO2 in all of them. At the same time, soil microbes are releasing CO2 in their normal metabolism. At the same time, CO2 is heavier than air and tends to remain close to the ground, especially in the morning and especially in tall grass where the wind needs to blow harder to blow the CO2 away. When you combine all these events, you get the stomata getting more CO2 because there are more of them, and because the amount of CO2 is denser near the stomata due to the taller grass and microbial off gassing. So the stomata close off earlier in the day shutting off the transpiration of water vapor from the plant and allowing the plant (and soil) to retain water better.
So taller grass needs even less water than short grass for these two reasons.