Weird that it's green down there. Is the pot somehow translucent so a little light gets in? Anyway, toss it in the compost pile.

My name, Your rose has something totally different. It's called a rosy gall. Seems to be a more northern problem than southern US. a good wiki page with photos I don't agree with which roses get it (in my garden it was all over R. eglanteria), and it sapped the strength of the plant. They don't add anything good to your roses, and If it were mine, I'd at least remove the gall and kill the bugs inside.

I've never tried them but if you're worried about the reservoir getting too full (and that's a good thing to worry about), you could just drill a hole in the side of the pot at or near the top of the reservoir. The reservoir will fill to the spot you choose and the excess water will spill out the side instead of going up past the reservoir. Here's what I'm thinking though: If the water is low enough in the reservoir that the roots don't get root rot, then that means the roots aren't touching the water....what's the function of the reservoir? If your roots can get to the water in the reservoir, that means their sitting in water and they could very easily start rotting. I think your gut reaction was right. I don't trust this drainage either. Besides, it's such an inexpensive and simple design. If it consistently worked the way it was supposed to, every single one of the commercial nurseries would have jumped all over it. Especially here in So. Cal. where water restrictions are putting wholesalers out of business. They'll try anything to save water at this point. I would just punch holes in the bottom and use it like any other pot.

Speaking of daturas reseeding themselves - a neighbor let his do their own thing, whereas I personally scraped out and scattered the seeds from the pods. We had a very wet snowy winter. This year I have over a dozen plants that sprang up where I scattered seed. He has nothing. I know he had seed pods on his plants, but I wonder if they ever opened. And here's another fun fact, my daturas are flowering at 4" and 6" tall!