I personally would use the systemic/imidacloprid. I don’t use it a lot and pretty much use it as a last resort type of thing. You’ve got root mealies on a bunch of plants, so imo that’s the best choice. I’ve always used it as the directions instructed, but don’t over do it, do the exact measurements because when I first used it I thought I would add a little more to the the mixture, more the merrier right? No, I ended burning the plant. I’ve never had issues with the ratio that’s in the directions.

Once the mealies are gone replace the pots with new fresh soil and scrub those pots clean. Go over all the plants and if you find any hanger oners you do the rubbing alcohol treatment. Let the plant/roots dry in a safe spot for a few days, and repeat if necessary.

Goodluck🙂.

Edit: I read your post wrong, so you don’t have anymore Bayer 3 and 1?

If root mealies are the only issue, you don't really need a systemic. You need to poison the media. Try Bifen, or perhaps a similar termiticide. Pour into the soil, has a residual of at least a few weeks. Safe for plants, rated for mealies: https://www.doyourownpestcontrol.com/SPEC/LABELS/Bifen_IT_Label.pdf

Doug, so sorry. No help but sympathy. Not a fun project.

Arrrgggh. I hate these. You need "the big guns". I would dispose of the worst. I made up the systemic insecticide mixture and acdtually thoroughly watered/soaked the soil with it as well as sprayed the foliage. Good luck!

I battled root mealies in a lot of my plants in the spring of 2019. I used imidicloprid on all of them and it knocked it right out. I can no longer get it in CT, but can in Mass... so maybe a trip to a hardware store or Home Depot in Mass? These days that might be hard; I don't know if Mass restricts people coming from New York right now.

There's a good thread over on Cactiguide that talks about using it, and what dilution you need.