Any help on ID'ing the weed in this photo, and the best herbicide to spray on it? It's on my St Augustine lawn in Houston.

It is Burrweed. I have it all over my yard and in the summer you cant walk in the yard barefoot or you will have stickers all in your feet. People say winter time pre-emergent will prevent it from germinating, but I have had no pre-emergent luck. I have tried certainty herbicide with no luck. I have tried 2-4-d with varying degrees of success. My wife and I have spent hours pulling it up only for it to come back worse. The only thing I have found that worked is non-selective herbicide then get ready for it to come back next year because the pre-emergent doesn't work on this God forsaken weed.

I have declared war on it this year. I am ready to light my yard on fire to get rid of this crap. Following to see if anyone has any recommendations I haven't tried yet before I torch the place.

Godspeed brother, this weed is not for the faint of heart LOL

Only luck I've had is Celsius in early February when they are just getting started. Once they get bigger it will still kill the plant, but the burr (and seeds) will have already formed, so the pain will still happen. I was late spraying this year, but after knocking them back last year there have been a lot less.

It's already getting hot for using a post emergent, but I've had good success with a combination of liquid Atrazine and MSM. Make sure to use a proper surfactant.

Maybe try image

as soon as I started to regularly use pre-emergent on my StAug I started to get fungus. My research points at pre-emerg weakening the root system. Might have been other factors at play but I had more issues with pre-emerg than i ever have.

I finally broke down and have a lawn service handle the fertilizer and weed control and my lawn has never looked better. Been on a regular plan for a year or so

CapCity12thMan said:

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as soon as I started to regularly use pre-emergent on my StAug I started to get fungus. My research points at pre-emerg weakening the root system. Might have been other factors at play but I had more issues with pre-emerg than i ever have.

I finally broke down and have a lawn service handle the fertilizer and weed control and my lawn has never looked better. Been on a regular plan for a year or so

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Interesting! I'd never heard of pre-emergent leading to fungus.

In my experience it was too much nitrogen (using too much fertilizer) in combination with cool temps and the lawn holding too much water…

I too experienced bad and reoccurring Take All Root fungus after regular use of Prodiamine. My assumption is that I accidentally overdosed which has lead to prolonged stress to the grass roots/runners. It has a very long residual in the soil, even despite diluting with additional soil. This the third season without Prodiamine and the grass is gradual getting better (and the weeds are starting to return too). Use sparingly and with caution.

I've found that about the gentlest is liquid Atrazine, which is rated as both a pre and post emergent. Stay away from the granules which have a bad runoff reputation and can root prune oaks.

Pre-emergent can prune roots, but I think people just assume every yellow blade of grass is TARR. Over-application of a pre can cause yellowing, with Atrazine being one of the more common ones.

I haven't applied pre on my lawn in 3 years. I do regular fungicide applications, aerate, gypsum when I find it on sale and fertilize. I still get yellowing every year. All the areas are where there's shallow tree roots, poor drainage or a popular high traffic area.

So could it be pre, yes. I've seen a lot of lawns from DIYers that over-applied a weed and feed and it made their lawn look a toxic yellow green. Could also be a lot of other things but the leading cause is roots and nutrient uptake or a lack thereof

Pre-emergent doesnt lead to fungus, but high nitrogen fertilizer can when timed poorly.

Atrazine should be a last ditch effort since it can damage tree roots and has the bad habit of runoff.

Healthy lawn in general crowds out weeds.

St Augustine sucks as a turf.