It could be japanese maple leaf scorch, an underwatered japanese maple or pests!
43+ What Causes Hosta Leaves To Turn Brown. A soft, brown, mushy decay may be seen at the base of the petiole sometimes accompanied by these structures, called sclerotia, are a cream color when young, but gradually turn to a dark, brick red color. They form a shelter by joining two ends of a leaf together with their silk.
Recently Transplanted Hostas Are Developing White Spots On Leaves Is This Ask An Expert from ask.extension.org
The leaves on your stromanthe could be turning brown for a number of reasons, but don't fret! I am not sure what is causing this, does anyone have any ideas? The stems may also turn red at the point where leaf spot is caused by the fungus mycosphaerella fragariae.
Disease symptoms on hosta start as marginal yellowing and browning of the lower leaves.
Choose varieties that can withstand the sun, such as sun power. Leaves may dry, turn brown, and become brittle. Too much hot, direct sunlight can scorch the leaves of some varieties, causing them to turn yellow and brown. If you notice your plant's leaves turning yellow, get ready to play plant therapist and check for signs of stress.
