Based on the additional info, I'm going to guess you have a combination of fertilizer burn and sun burn. I think there's a couple of things going on here. Container culture is very different than planting in the ground, and even If planted in the ground I wouldn't plant a Japanese Maple in a mixture of 50% compost. My guess would be your tree was showing signs of fertilizer burn from the compost, and the high temps aggravated your already stressed tree. I believe I remember reading that when nutrients are too high in the soil, a plant isn't able to absorb water from the soil. With the high temps the tree needed even more water but couldn't get it due to the nutrient imbalance. At this point, if I'm right, I think your only option is to get the tree out of the compost mixture. Did you bare root the tree when you repotted or did you pot up ( ie take the tree out of the pot, loosen the out side roots and pot into the large container placing the compost mix around the existing mostly intact root ball? Reason for asking is, if you only potted up you can likely plant the tree in the ground for this year or pull the plant out of the compost mixture and pot up using a soil with similar soil characteristics as the soil in the root ball. Be careful and try not to disturb the roots any more than necessary. You're getting late in the year to be potting up but leaving the tree in the compost is likely to do more harm. Also keep the roots moist as best as possible during the procedure. If the roots dry out, they'll die and cause even worse problems. The tree should be moved to a shady area protected from wind, after or during the pot up/planting, until it begins to improve. Also a note on full sun, some cultivar of Japanese Maples are listed as capable of being planted in full sun. This is a misnomer because full sun in Japan, western Washington, or even in the north east is different than full sun in California, Texas or Georgia. Although some of the Sango Kaku's are among the more tolerant of sun exposure when planted in the ground, I've read many examples of these trees showing sun exposure stress symptoms when in hotter climates in containers. Hope this helps, and also hopefully one of the others will come along and correct me if I've given information that's too far off the mark. PS The above recommended procedure would only be a temporary fix. Next spring, just as the buds begin to swell, the tree would need a full repot into an appropriate container medium if you wanted to put it back in a pot or keep it in a pot which ever the case may be. Blake

If you have seed "balls" then they are most likely sweet gum or sycamore tree leaves rather than maple - maple tree seeds are like a small green feather. The balls do take quite a bit longer than the leaves themselves to decompose so it's best to remove them as much as you can. Decomposing leaves, by themselves with no other added organic vegetable matter, make what is called leaf mold rather than actual compost but it is quite good for mulch and improving soil. It just takes more time for it to develop. Holly leaves are quite slow to decompose because of their high fiber content. Again they make a good mulch around flowers and such but I avoid using them around food products. Hope this helps. Dave

Every fall, and often in the spring too, I would pick up those bags of leaves people would set out by the curb for pickup, take them home, and often shred them to make compost or use for mulch or sometimes leave them whole and use them for mulch. Shredding those leaves allows the bacteria to digest them faster, although they will digest them even if they are left whole eventually just as they do in the forest. Whole leaves spread on the garden as mulch do as much good, eventually, as shredded leaves put on the garden as mulch, but those whole leaves can suppress some plant growth just as whole leaves cause problems with some early spring flowers by restricting access to the sunlight plants need to grow. Tilling those leaves in to the soil could cause a temporary loss of Nitrogen as the Soil Food Web uses that N to work at digesting those leaves just aas they do with any material that has a high Carbon to Nitrogen ratio, leaves range from 40 to 80 C:N ratio. Double digging might be necessary once, but has no real benefit if done once the soil problems have been corrected. Here is a link that might be useful: About Double Digging

My yard has two large maple trees, and is bordered by other deciduous trees. I raked the leaves into a long, tidy berm at the back of the yard, about 6' wide by 25' long. It was about chest high originally but has already shrunk down to half the original volume in a few months. I know shredding them with the mower would speed up the composting, but I prefer not to use the extra fuel and create noise pollution. I suppose others would find it a lot of labor, but I am easily amused and enjoy the exercise - by using a large tarp to drag the leaves I can keep the pile neat with minimal effort and almost no lifting. I also add kitchen waste to one end of the berm, and add horse manure when I get the chance (my friend works on a farm and I bring along a 5-gallon bucket when I visit him there). I plan to work a lot of the mulch into my vegetable garden in the Spring. When I lived in SE Mass years ago, I kept chickens & it was swell to throw all my (mostly oak) leaves into their pen - they'd work them over for the bugs and add their alkaline waste - it all broke down into wonderful soil - bright green grass sprung up right under the white pine trees (where no grass had grown before) when I moved the chicken enclosure.