not to worry! that looks like a pretty happy oleander. soon you'll probably be at that thing with pruning shears to keep it from eating the rest of your yard unless it's in a spot where it can get big and not hurt anything. I was given an oleander by my neighbor who had it in shade, so it wouldn't grow. It was a straggly 3' tall twiggy thing with two sets of leaves. Within a few months of being moved into full sun, it took off. Unfortunately, I planted it right next to my driveway, so I'm pruning the darn thing every month right now just so I don't graze it with the car every day. I'll be moving it this fall. Now, a question for you: I take it you like plumeria? I bought one in Hawaii once, but never could get it to grow. It just shriveled up. What part of TX are you in, and what's the best way to get one started? Pot size? Soil type? Fertilizer? Water usage? THANKS!

It is hard to tell them apart. Because you said that the leaves looked OK earlier it is most likely mites. FMV will often show early in the season and then get better, while mites cause more symptoms as the season progresses and their population increases. They are the vector of FMV so be careful to not spread them from tree to tree on your hands and clothes. It seems like Avid is natural but not organic for some reason. Be careful to not get in your eyes or on your skin, read the label, get very good coverage- inside to outside, bottom to top.

Does the pot have a hole in the bottom? It should. What's the potting mix are you using?

It’s normal to lose some of the lower leaves - they age out, or they get shaded out and the plant sheds them as they no longer do enough photosynthesis. Usually the rate of loss is less than the rate of replacement by new leaves but it sounds like you’re losing more than that. Maybe watering every three weeks is not enough, you may be stressing your plant too much. Of course it depends on the plant the soil the season the pot size etc etc, but my one dries down in 7-10 days and then I water it thoroughly and drain it well. Then wait again to dry down, as judged by the weight of the pot and/or whether a skewer inserted down to the bottom shows moisture. Read up on soils and watering on this forum, I think that’ll help. Don’t think it’s a disease. Could be rootbound though, looks a small pot for its size. Which will make it go through water faster too. I agree give it bright light.