What is a good potting soil mix for a potted Japanese Maple?
A mix of 30% potting soil, 50% pine bark and 20% perlite will give the tree a mix that drains well and allows air exchange.
Avoid peat moss and sand.
https://www.gardeningknowhow.com/ornamental/trees/japanese-maple/japanese-maple-care.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/growing-trees-in-containers.htm
Austin Tx, wet spring, JM in pot, 5 yr old, in filtered light suddenly brown dry leaves. Green and dry dropping. Branches look somewhat ruffled.
Yes, your tree may very well be suffering from root rot.
Make sure the excess water is allowed to drain from the soil.
If the container is on a flat surface, you can 'lift' the container to make sure the water is draining.
Move the container to an area, if possible that rain water does not hit the tree.
Allow the container to dry out and wait and see.
https://www.gardeningknowhow.com/plant-problems/environmental/excessive-rain-on-plants.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/growing-trees-in-containers.htm
https://www.gardeningknowhow.com/plant-problems/environmental/overwatering-container-plants.htm
https://www.gardeningknowhow.com/ornamental/trees/japanese-maple/japanese-maple-care.htm
I have seen a Japanese maple tree that is approx. 5 feet tall. The leaves are the larger, not lacey type. The tree has about 5 to 6 biforcations. Half the tree is green, half the tree is purple. Its color is evenly split in half. Does anyone know the name of this tree?
Most Japanese maples are grafted varieties, since growing them from seed is challenging. Since that's the case, you can't ever be sure that the result of a graft will look the same as the parent plants or that it will look exactly as what was hoped for. It sounds like the tree you saw may be a grafted cultivar, and if that's the case, it would be difficult to identify what variety the parent plant(s) were.
You can read more about grafting Japanese Maples at https://www.gardeningknowhow.com/ornamental/trees/japanese-maple/japanese-maple-grafting.htm
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I have a newly planted dwarf Japanese maple and it has yellow stuff on the bark that looks like a fungus or a mold. How do I treat this?
Without a photo, it is hard to say, but I will give this my best shot.
It probably is yellow lichen - in which case it is harmless. Here is an example of what yellow lichen looks like:
http://gardenworldimages.co.uk/ImageThumbs/LLT1234/1/LLT1234_YELLOW_LICHEN_ON_TREE_BARK_XANTHORIA_CALCICOLA.jpg
Here is an article on tree lichen for more information: https://www.gardeningknowhow.com/ornamental/fungus-lichen/treatment-tree-lichen.htm
If it's not lichen, then it's going to be either a fungus or a mold but it would be difficult to propose a treatment without a photo for identification.
I have a two year old Japanese maple. Last spring the tree fully budded and produced a full leaf bloom. This year, only half the tree has leaves. I have not given up hope that those branches will bud because they are not dead. Is there anything I can give the tree to help it bud? Is there a deficiency that would cause this?
If the tree is still leafless several weeks into spring, it has likely died.
Since you have some leafing branches, check below the bark by scratching the bark.
If it is green there is still life, if it appears tan.
If the branches are still alive it may be that a late frost killed the buds.
In this case the tree should leaf out next year.
https://www.gardeningknowhow.com/ornamental/trees/japanese-maple/japanese-maple-care.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-scratch-test.htm
I have quite a lot of brown/white sticky things on my red Japanese acer. They are on the trunk of the bush. My neighbor thought it was some kind of spore, but I am not sure and would like to find what to spray it with to get rid if it.
A photo would aid in my identification but I will give this my best shot. My best guess, given that you used the word 'sticky' is that your acer is afflicted with a honeydew secreting insect such as scale, aphids or mealy bugs. For more information on these insects and a course of treatment, please visit the following link:
https://www.gardeningknowhow.com/plant-problems/pests/insects/control-plant-scale.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/homemade-aphid-control.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/mealybugs-control.htm
About 75% of my red weeping maple has only tiny dried up curly leaves on the branches. I have a 5 year old red weeping Japanese maple and this year only one section bloomed with healthy leaves. I just pulled off all the old mulch and some of the mulch has a white substance on the bottom of it. Someone suggested I gently scrape a couple of branches and if there is green below the bark they are not dead branches. I gently scraped and below the bark was only white or a cream color. 25% of the tree has healthy leaves and I just saw a new shoot of healthy leaf out from the trunk of the tree. Do you think this is a mulch fungus problem or something else could be the cause of the problem?
The white substance under your mulch is likely only the naturally decomposing material, but this article will give you additional information and ways to identify other types of mulch fungus:
https://www.gardeningknowhow.com/garden-how-to/mulch/common-mulch-fungus.htm
The dried up curly leaves "could" be something as simple as not enough water, but not likely. Verticillium wilt is common in Japanese maples but the leaves turn yellow before falling. The most likely cause of your maple suffering (based on the symptoms) is aphids. This article will help you positively identify and remove them: https://www.gardeningknowhow.com/plant-problems/pests/insects/aphids-tree-disease.htm
And this article may also help you: https://www.gardeningknowhow.com/ornamental/trees/japanese-maple/japanese-maple-problems.htm