Mike, Thanks for taking the time to answer, I appreciate all the help and patience that all of you give to those of us just starting out. You are right - determining moisture can be difficult. I had the wooden dowel up too high. When I inserted it deeper into the pot, I found it to be very moist indeed. I have cut back on the watering; I haven't watered for a week. Maybe that will also eliminate the gnats. I haven't noticed any newly yellow leaves for a few days, so I am hoping that correcting for the very low water pH has also had a positive effect on absorption. As for the fixing the mix, I wouldn't know where to start improving it. Well, I've got some ideas... Maybe, some of the bark pieces are too big compared to perlite(the bark was screened through a 1/2 inch screen and the perlite was rinsed over insect screen). Is the bark too big or the perlite too small? Here's a picture. Any other suggestions for improvement are welcome.

The plant in my yard that shoots seeds, my sister calls it Artillery weed, has a small rosette of basal leaves and then a flower stalk with tiny white flowers. Oxalis makes a seed pod that looks like a tiny banana, in fact I liked to eat them when I was a kid as they tasted acidic. I'm not aware of them ever shooting seeds at me. Perhaps we're not all talking about the same plant. Oxalis looks like a three-leaved clover. There are photos in the Paghat link in my previous post. I spend a lot of time in early spring trying to get all the "artillery weed" before it starts shooting seeds, I hate it too. But I like Oxalis a lot. If you know the ingredients for the Burn Out II, maybe you could try to mix up something similar. Azure Standard has clove oil. I've heard of using vinegar and a little orange oil cleaner mixed in to kill weeds.

Actually, all dogwoods have tiny flowers like that. Some just have showy bracts that we think of as the "flowers". That's what those big white "petals" are on Cornus kousa. The flowers on those are the tiny ball of white, green or yellow florets at the center.

Before we get to the problem you think you have, let me go to the real issues :-) Or you can ignore what I say and skip to the bottom two lines for thoughts on your leaf issue. Are you afraid to trim the low branches for some reason? Get those low branches off the tree, tie it to a stick for support, ALL the way up, not 12" from the ground only, lose the fruit and train it in a straight upward growth habit. I let my three grow to about 5 feet then snipped the top to force branching. Once it branches, let the branches get long say 3-4' tip prune them to force more branching cutting off branches that grow downward. This way you will be able to move around the tree and pick fruit easily as it matures. Carambola start life VERY scraggly and you need to help it get strong. In 4-5 years with help from you it will be strong and give you more fruit than you and your neighbors can eat. If you want fruit today, go to Publix :-) If trained properly you can let it keep fruit when it's strong enough to not break or deform under the weight of the fruit. That said, carambola are VERY disease resistant in so. Fla. and with your tree so low it's hard to tell if it's cat spray, yard spray, direct fertilizer burn or maybe something else spraying on it from say a neighbor, splashing from your roof or from your lawn mower debris landing on it. To me it looks like mineral oil spray burn. Have you sprayed it? Ever? The only foliar spray you may need is to cure chlorosis which is not life threatening to the tree, but foliar nutrients will not burn it. Look up chlorosis your tree does not have it. Trimming and thinning branches is a lifelong job. They will have LOTS of dead branches that need to be trimmed OFTEN so you can get up in it to harvest fruit by hand without poking yourself in the eyes with dead branches. Carambola fruits don't do well with fruit pickers that I have tried. Finally, the worst things that can happen to Carambola are drying out, chlorosis, a hard scale (seemingly harmless to the tree) that gets on the branches. Frankly they're hard to kill, I know I had a devil of a time killing a Bell two years ago rather than bringing in a stumper. About your custard apples, Are those new flushes? Anonnas get white fly (look under the leaves for them) and "maybe" scale but for the most part are also pretty disease resistant. Bottom line is, I suspect something airborne is causing those spots on both trees. OR it "could" be bacterial leaf spot. See: https://www.planetnatural.com/pest-problem-solver/plant-disease/bacterial-leaf-spot/