[Gorgonzola17]

Ok, so I have tttf in the southern part of the transition zone. So I had some dallisgrass invading the lawn last season, but overseeded and aerated last fall and have prepared the turf the best I could for the brutal summer. Temps are already in the 90s regularly down here. I didn't realize how much dallisgrass I had in the lawn until recently because the seed heads are only now starting to pop up. Every time I see one I do my best to pull the whole bunch out by the roots. I have some msma, but I am trying to figure out the best time to treat the Dallisgrass. I know the fescue is going to be fighting for its life shortly so I am afraid if I apply a herbicide like msma now, I may lose alot of my turf. I also know if I kill the dallisgrass the fescue will not fill the bare areas in, and I will probably promote more weed growth. Looking for any opinions on best way to address this.

 

[social port]

I can't give you a definitive answer, but here is my take.
Dallisgrass is nasty stuff, and you do not want it spreading.
It is also hard to kill.
Fluazifop is another option, though I suspect you will be risking damage to the fescue, especially at temps 90 or above.
If it were me, I'd spot spray very carefully and lightly on non-windy days or paint with glyphosate, depending on the extent of the invasion. You will likely need to reseed anyway this fall after the summer heat.

I've never taken dallisgrass out of fescue, but that would be my starting point at least.

Here are a few programs to consider:
https://extension.tennessee.edu/publications/Documents/SP642.pdf

 

[gene_stl]

My lawn was starting to look like an OK tier one lawn except for dallis growing faster than the kbg. The article linked above is the best one that I ran across especially for cool season lawns.

Declared war on dallis grass and fired a serious opening salvo.
Got my bargain Fimco LG-5-P cranked up and used it , to spot about 2/3 of the the dallis in front.
It was quite a witches brew. I used about four gallons of water. I put in a strong dose of Tenacity. I put in a good dose of Sedgehammer. I put the rest of my Ortho Crabgrass Killer from a hundred years ago which still had about six ounces of Calcium MethaneArsonate. I put a one third dose of Ornamec 170. Blue dye and spreader sticker.

We'll see how it works. Shouldn't be any worse than spotting with RoundUp or a Torch.

I added some fluazifop at about a 1/3 rate because my lawn seems to be a lot of kbg. But I note that this agent is labeled for use on tall fescue so if your lawn is tttf you should be able use it full rate. I also added some Sedgehammer because the article referenced sulfonylureas. I think if you have MSMA that is the magic ingredient. With the above mix the dallis withered very quickly and is mostly gone in the section I sprayed. I was worried that I might injure the lawn but it has been mowed once since and seems to be fine, so far. There are a few clumps that got wounded and are not dead yet but they don't look like they are going to come back. Especially since they are going to get sprayed again. :twisted:
I am going to do the parts that were left after I ran out of spray today or tomorrow depending on the weather report and radar map. MSMA likes to be applied in hot weather. Most of the other ones have a temperature limitation but if you spot spray it won't be like Roundup or a torch. Even if you do have some damage it is better than letting the dallis proliferate which it will. One disadvantage to the above approach is I don't know which agent was the most effective. But I want the dallis gone and this is my second summer in the house. Last year I wasn't prepared to spray and I went out with a weed torch but there was so much junk in the lawn it was fruitless. This is probably the time of year I lost the battle. This spring I was ready.

 

[nclawnguy]

Just hit with glyphosate, this way you know it's dead. I've had a good kill rate with it vs dallisgrass.

 

[beastcivic]

No time like the present! That's a nasty weed, kill it ASAP.