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

I see this effect on my 'Bloodgood's when they get Verticillium wilt. A slow gradual die-back from the tip to the trunk. When you cut the dead branches, did you see areas of jet black or jet black partial circular rings? I hope you sterilized the blades after each cut. If you have V wilt, you can extend the life of the JM using a product I buy from Mountain Maples in California called Phyton 27. If you have V wilt in will remain in the soil almost forever and you'll need replant a V wilt resistant plant.

Depends where it came from and the zone it WAS in. Most Jap. maples are in dormancy right now and in fairly cold zones. All my jap. maple bonsais are in the garage now and for at least another 6 weeks or so. That garage is unheated and has been just above freezing to just under freezing for the last 5 weeks or so. No sun and watered only twice. If they were to get into zone 10 heat and even diffused sun it would definatly shock them and probably kill them. It takes about 2 weeks of slowly and gradualy introducing them to sun and warmth in the spring to get them ready for outdoors. I would say next time order in the late spring and summer which should be closer to your zone from their originating zone, then still keep them in a cool shaded place for the first 4-5 days. Even so, in your summer heat they should not get direct afternoon sun. Some early to mid morning sun will be fine and you may need to water a couple times a day during the worst heat. They survive cold better than they do heat. John

After 4 years, whatever fertilizer may have been present in the potting soil is long gone. And most good quality potting mixes do not contain any fertilizers to begin with. Anything grown in a container will need routine fertilization because of this fact - there are really no nutrients of any significance in a potting mix and container grown plants rely entirely on the gardener to supply their nutrient requirements. I grow all my JM's in containers and add a slow release fert (Osmocote) when potting them up initially. And I sprinkle a generous amount of the same product on the soil each spring if no repotting occurs - this will last the entire growing season. Plants grown in containers require very close monitoring for water needs, especially in a hot and dry summer. You can't rely on any schedule but must check daily. As you can see, drying out of the soil and subsequent leaf drop/drying can happen very quickly. The good news is that if this has not been overlooked for more than a couple of days, a good deep soaking and adequate watering attention thereafter will result in new leaf formation.