Far from an expert, but...
I renovated a relative's yard a number of years ago (slit seeded a Northern mix) and had a continuation of a pre-existing heavy chickweed (mouse ear) infestation. Used Weed-B-Gone CCO and it resulted in a good kill off, but the chickweed returned the following year and the lawn began to thin. The Fall of the second year I did an overseed (no slit seeding) and used the Scotts Starter with pre-M (can't remember which AI as they had two formulas at the time. One with mesotrione and another with Sudifan?) Point is, that reduced chickweed the third year and a follow-up the third Fall with prodiamine has virtually eliminated chickweed.

 

opted just to aerate the front yard this past fall.

... then...

I'm slammed with chickweed in that area now

If you don't have construction-heavy equipment compaction or another compelling reason to mechanically aerate, the risk of weed propagation is one reason to avoid it. Especially if you stir up and spread seeds on existing plants that germinate and grow into the winter, like chickweed. Chickweed produces seeds at a very low height of cut pretty early on, grows in much colder temps. It's likely you encouraged it to spread by moving all the seeds around and shaking them off the plant - especially if you had no or little pre-emergent protection at the time.

So - a couple things you can do.

1 - skip the core aeration of that area unless you have another reason to do it
2 - do a split application of pre-emergent so that you get some late fall / winter protection when weeds like chickweed germinate.
3 - use multiple, repeat applications of triclopyr with a good surfactant to kill it this spring. The plant is dense, short, with lots of material. I've noticed the first application will kill the top part it touches, then I'll need more applications to keep working down.

I've tried mesotrione on it but it isn't as effective as triclopyr.

Yes, you can spray it late fall / early winter when it's growing with triclopyr. Spot spray though. Blanket spraying will hurt other things that don't grow much that late in the season, like your KBG. Don't want to head into winter with a mess.

So, kill it with triclopyr, now and late fall. Prevent with a good pre-emergent - split apps will help (I use prodiamine). Don't help it propagate itself.

 

@HoosierLawnGnome thanks, yes, I'm typically against aeration, the front yard was the contractor "parking" this past summer during our reno. I'll bust out the triclopyr when it stops raining. There should be enough KBG there to spread so I can keep the pre-E barrier down into the fall and eliminate the chickweed seed germination.

 

Far from an expert, but...
I renovated a relative's yard a number of years ago (slit seeded a Northern mix) and had a continuation of a pre-existing heavy chickweed (mouse ear) infestation. Used Weed-B-Gone CCO and it resulted in a good kill off, but the chickweed returned the following year and the lawn began to thin. The Fall of the second year I did an overseed (no slit seeding) and used the Scotts Starter with pre-M (can't remember which AI as they had two formulas at the time. One with mesotrione and another with Sudifan?) Point is, that reduced chickweed the third year and a follow-up the third Fall with prodiamine has virtually eliminated chickweed.

Thanks. I used mesotrione at seed down, but have always found it to be a better post-emergent. Hopefully I can just use the pre-emergent barrier this fall to prevent further germination.

 

Yeah, I used the granular (starter with prilled pre-M) which I think does a better job than spray) of creating a soil barrier, but all in all, I've never had great results with the turf-safe (mesotrione) as pre-Ms, the reference above was for purposes of full disclosure . Pretty sure the elimination was due to the prodiamine. Anyway, the prodiamine did work in this case (just short of max rate, early August app). Good luck.

 

If you have KBG then feed it well this spring to get it to fill in. When I did the Reno it was late in the season so spring time it still had bare spots. But regular spoon feeding of urea it filled in all those spots fast. Just mow as often as possible to encourage it to fill in.