I think you may have 2 separate problems, judging by the photos. The white spots are probably powdery mildew, which is a type of fungus. If you're not growing organically, you may wish to treat with daconil; there is one specifically for fruits and vegetables, so use that. It's very effective. If you are growing organically you may, as suggested, try neem oil. However, don't apply it in sunlight and don't apply it if you expect temps over 90 degrees Fahrenheit, or it will burn the leaves. You may want to try a sulphur-based insecticide. "Safer" puts out one of those, but read and follow the directions, and make sure it's safe for vegetables. It is treatable if you start working on it before it invades lots of leaves and weakens the plant. =================================================== Now, about that pepper plant. It could also be powdery mildew or it could be another, more serious disease. If you're not seeing white and/or diffuse yellow on the leaves, then it may not be powdery mildew. You folks in the south get some plant diseases that those of us in the cold zones rarely or never experience. I'd feel a lot better if someone who is familiar with your part of the country would chime in. I hate to speculate, but... First, if the pepper is planted in soggy ground that does not drain well, that could be your problem. If the other plants around it are not having problems, I'd suspect a virus, root nematodes (we don't get those up here), or soil-borne bacteria (we rarely have to deal with that either). I don't like the way it is wilting. If sitting in water is not the problem, I'd suspect a systemic plant disease. I'm sorry to say that you may have to destroy the plant if it doesn't improve in a few days (and I doubt it will). By "destroy" I mean you must dig it out, root and all, and put it in the trash. Don't compost it and don't leave it around; if it's diseased you don't want to contaminate other plants. Since peppers are related to tomatoes, eggplant, and potatoes, it may infect those plants if you have them. Try googling "peppers wilting" and see if can diagnose the problem. Again, I don't have any experience with some of the diseases that are common in your part of the world. Link below to University of Florida info on diseases of peppers in FL. Best of luck. Here is a link that might be useful: UFL Pepper Diseases

Pearl ... Also make sure that your plant is getting enough LIGHT. African Violets need 10-14 hours/day of BRIGHT light through a window ... or indoor fluorescent light. When I finally was able to keep my African Violets alive, ... I next learned that I needed to keep them in BRIGHT LIGHT multiple hours per day to get their flower buds to open. Those plants that I didn't get into a well-lit location would not open their flower buds, even if the plants had flowers and buds when I brought it home. Those buds would just brown and die. So check your LIGHTING. An easy way to make sure your plant is getting enough light is to purchase an inexpensive desk-lamp and use one of the 60 W fluorescent spiral bulbs in it. Train that light onto your African Violet during your waking hours, and I guarantee that you will get bloom. Examples of such lighting setups are displayed below ...

I'm so sorry, but, it doesn't look completely dead yet. Your potting mix looks very wet or is it just very black? Young lychee plant don't need the extreme moistness of larger trees does. Carefully pulled out the tree and look at the root ball/system. If they are still whitish and not dark brown. Then the lychee still has a fighting chance. All those leaves will eventually drop or you can pull them off now. It will be a slower process to regrow new leaves, but, if the root system is dark brown, then it is most likely dead. But, whitish roots, still have hope for recovering. Will be slower, but will recovered. I have some young plants like that too, all the leaves died and turned brown. But their root system is still alive, just took longer to recover, after such a stressful period of leaf drops. Hang on to the little guy, it will recover, eventually. Just don't give it water unless you notice the soil is getting on the dry side.

Here is a photo of the plants.