The crabgrass preventer doesn't kill the existing crabgrass. It just stops new crabgrass from germinating. It actually probably stops any seeds from germinating, including grass that you want to grow, so don't put it down if you plan to seed grass. You need to wait until the new grass you've seeded has sprouted before putting down any preemergent. In fact, you may need to wait longer than that (sometimes until you've mowed 2 or three times). There should be details on the label.

Hi bpgreen, thanks for your reply! I see... it IS only a preventor, I should've known better. I will postpone to put down the Fert w weed prevention until I clean up existing weeds. Although I'm not looking for pefect turf, I'd like to stop this weed infestation and get more healthy lawn. A garden store person suggested to cut those crawling types of weeds by weed eater to the ground and put down some sods so that Bermuda will take over. Would you all the experts out there agree with this? If anyone could give me any advice, I'll be really appreciated.

Thanks for your time!

Here's pic of my lawn,
http://i216.photobucket.com/albums/cc262/aloha_beachdog/0710020032_.jpg

The first thing to do to get a handle on it is keep your Bermuda cut very short at 1-inch or less and mow at least twice a week or more.

texas-weed, Thank you very much for your advice. I will definately change my mowing routine to twice a week and keep it 1 in.

As for existing weeds, I can no longer catch up by hand-pulling/spot treatment. Living in Hawaii, I don't think weeds would ever go away (We moved here recently and not too familiar with lawn care in Tropical climate). After I clean up this mess, I'd like to overseed to fill in the thin area and bare spots where I pulled weeds.

Here's my question,

Is it necessary to spray Weed B Gone for whole yard as almost 1/3 of lawn is weed infested? Or as long as I cut the grass short and contain spread/growth of weeds, would overseeding Bermuda take over afterwards?

Thank you very much for taking time!

Mowing is one of the most important aspects for maintenance of a good quality lawn. Mowing increases turfgrass density, producing a tighter lawn that is resistant to weeds.

The Bermuda should crowd out the weeds If you mow at 1" twice a week as suggested. Also Bermuda needs to be Fertilized once a month. At minimum fertilize every other month during the growing season.

Thank you so much for the mowing/fertilizing tip, skoot cat! I just cut the lawn close to 1 in and it'll be 1 in next time I cut it! I'll always keep it up from now on.

Please see the pic (crop of bad area):
http://i216.photobucket.com/albums/cc262/aloha_beachdog/0710050005.jpg

This crawler (I think it's a kind of WireGrass) escapes from mower and they'll keep on taking over Bermuda at very fast rate.

What is the best thing to encourage Bermuda to take over at this point?

Should I start putting down fertilizer? Or do I need to overseed first as it's badly infestated by weeds with thin/bare spots here and there.

Thank you for your time. Any inputs will be greatly appreciated.

Maybe I missed it but if you are using Weed B Gone (most forumlations are for broadleaf weeds unless specified otherwise) so not going to do doodley about your grassy weeds.

Hi, thanks for your reply quirkyquercus!

I have been spot treating with Weed B Gon Crabgrass Killer. It lists crabgrass and dallisgrass which seems quite similar to what I've got. Since weeds infested my whole lawn, it doesn't do any wonders but at least it seems to stop weeds from spreading where it's treated.

I'm still looking for most effective way to deal with this sort of crawling weeds but I may be stuck with pulling by hands one by one for now :(

Since I've got Bermuda and everyone told me that it's the tough grass, I will concentrate on thickening the existing grass while I try to keep the weeds at the minimum and hopefully it'd win over the weeds.

I am still considering overseeding also and I heard there are fertilizer with crabgrass control which are made for newly seeded lawn (tuppersan/siduron based). That would save me from dilemma of overseeding VS fert w crabgrass control.

Have a wonderful weekend, everyone!