My yard is probably in the worst shape it has even been in regards to weeds since we built the house 20 years ago. The Dallisgrass or crabgrass is absolutely ridiculous. I have used MSMA in the past with limited success. My local feed/seed guy recommended it again. Only problem is, it only comes in 2.5 gallon jugs. That much would last me 20 years, I don't need that much. My yard is St. Augustine, and MSMA will kill St. Augustine. I was going to spot spray it and kill little at a time doing as little damage to my lawn as possible.

So I said all that to ask this question....why wouldn't Roundup do the same thing? It's going to kill the grass as well, but why wouldn't it have the same effect on the weeds?? I can buy it in much smaller quantities and its a ton cheaper.

The StAugustine will take over the crabgrass when it warms up a little. I had a good bit of dallas grass my first two years. I grubbed it out with a sharp garden hoe. Don't think I could do that again.

Whoa not so fast. The question is what happened to your turf? Heavy shade with Oaks? Poor fertility? pH out of wack? A well maintained St Augustine will outgrow Crabgrass and Dallas grass. It’s a bit early to fertilize but you can start with frequent mowing. Your weeds will not handle that. If shade is a problem you can fix that now. I would NOT go with herbicides on St Augustine. You can grow your way out of this problem. Good luck.

I have no idea. It was probably one of the best lawns I've had last year in the 20 years we've been there. I have 75-80% sun, one lone Bradford pear tree. House faces west. Only thing is my neighbor to the north (rent house) has a fairly large open lot that is mowed a fraction of what it should be. It is certainly not treated in any way. Definitely where the weeds come from. I have been able to keep them at bay for the most part, until now.

Won't help you this year - but next year when your st. augustine is still dormant, but your weeds are starting to grow - spray with round-up. DO NOT spray if there is any sign of life in your st. augustine - round up will kill it - bermuda can handle round-up at the right application rate, but st. augustine is very herbicide sensitive.

Just tell everyone that you are an employee of the Whitetail Institute and your lawn is research. That should get you out of mowing as well.

I would start digging it out now. After temperature highs are 80 degrees. You can apply round up with a foam brush to individual unwanted plant.