Our Red Maple (Acer rubrum) trees have leaves drying and falling in July. No sign of insects, just dry brown leaves. What's wrong?
I also have a red maple (Acer palmatum) on the balcony in a pot. Every year the leaves become brown as well in the summer, as if they are dried or burned up. I have found previous posts which might contain the answer. It might be too much direct sunlight (the tree likes shade), or it might be too much wind. My guess is the first (too much direct sunlight), since it always happens in summer (July).
See here for previous post about the brown leaves of Acer palmatum.
Without more information the best we can tell you is this is common for trees that have or are going through some major stress. This is probably due to temperature changes. Insects could do this as well such as a major infestation of some sucking or chewing insect. The tree's most vulnerable part is their leaves. That is why deciduous trees lose their leaves for winter and go into a dormancy...to survive a niche where there are winters.
If your tree wasn't watered enough in the last few months and that tree needed more water than it was given that is stress enough for your tree to start dumping high maintenance leaves and go into dormancy. Similar to people going on a dumb diet or worse, fasting.
Funny to compare a plant process with humans but this one makes sense. When people 'fast' their body immediately thinks something is wrong. The body assumes it is on a desert island without food without water. Without regular food and water our bodies will go into a survival mode. Fat is hoarded and saved from use by the body. The body instead starts dumping high metabolic tissue which is muscle. That fat is a safety measure. POWs, anorexics are clinically obese! Their heart muscle is the first muscle that starts getting dumped and they mostly die from heart failure.
The tree dumps its leaves in an effort to stop the necessity of water and chemicals if those aren't coming in on a timely basis.
Your tree will be fine...I hope. The important thing is your tree needs water and fertilizer. It will not be in total dormancy and there is the danger it might decide that it is SPRING and produce new leaves/buds. If this happens and winter hits your tree will probably not make it. Too much stress.
Fertilizer is as important as water and light. But just a teensy bit too much and fertilizer will kill your plants. They need a balanced fertilizer N P AND K. We need to know when you planted this tree, how well established it has become. We need to know where it is you live, what your growing season is...what fertilizer you've used and certainly some pictures of the whole tree and close ups of the trunk to soil connection and the leaves themselves to include whatever live leaves you've got left. Can you see if there is any new growth happening? Pictures of the undersides of the leaves. We can certainly try to walk you through this so you don't lose your tree, or at least try to avoid losing your tree!