Hi my Acer is a B&B and I planted it 1 month ago. A lot of leaves are browning and falling off. What do you think? Do you think the tree will die?
The blackening is probably bacterial in origin - for starters try searching "maple bacterial leaf spot".
We had the lots of rain this spring, the most we had in 125 years. Then we went into a very hot and humid period with abundant rain and no wind. The result is very uncommon foliar fungus and bacterial issues in a wide variety of plants in our area that never have a problem. Since you are east of us it's most likely you are expecting the same problems. Leaves on our very dense beni tsukasa is experiencing the problem you describe and what I see from your photos. Now that the rain has stopped and we are starting to get dry air and wind moving into the area, it seems to have stopped the foliage issues. New buds are forming and the tree looks good overall, just not as dense (it was actually too dense with foliage from all the constant growth that occurred from May-June with constant moisture). We did vertical mulch as a precaution because we thought the roots were too saturated since it was planted as a 45 gallon container (deeper hole to accommodate the massive roots) and the soil looked too saturated outside of the bed. We removed the damaged leaves by cutting the stalk and pruned out any thin crossing branches from the dense canopy. This allowed more light and airflow into the canopy. Damaged /brown leaves that fell under the tree were removed as a precaution. The tree is doing great now. Any thin twigs that defoliated now have extending buds and should leaf out soon. I can't say which did the trick or if all played a role. I normally only write on here about my personal experience developed over the years and since this never happened before I can't say absolutely "do this" or "the problem is". I was not alive 125 years ago and I never saw a spring like this before. To give you an idea of the abundant rain fall that occurred almost daily, my bonsai require watering daily. Because of the small pots and dense canopy I can only count on steady moderate rain to actually saturate the soil, hence the watering almost every day. Usually by July 4th I would have watered in a normal Spring about 50-80 times. This year on July 4th my total watering of the bonsai count was 5 for the 2019 growing season. Now that the rain stopped I have watered almost every day since. Anyway how is your tree doing now?