Hello,

I am providing you some information and at the end, I will provide a conclusion (Recommendation)

The tree is easily transplanted, grows quickly, and is adapted to a wide variety of soils (including slightly alkaline) and can tolerate shade, drought, and coastal conditions. It can naturalize if located close to open areas. Sensitive to poorly-drained soil, the tree responds well when planted in a mound with about one-third of the root ball above the existing soil grade. ‘Crimson King’ is reportedly more difficult to transplant than the species but is considered an urban tough tree due to its adaptability.

The Crimson King maple is susceptible to verticillium wilt, which causes branches to wilt and die. It is not always possible to spot the infection as sapwood staining (sometimes patches of dark or olive green) may not be obvious. Another problem is the girdling of roots around the trunk base, which gradually chokes the tree and can be fatal. Leaf scorch is also a common issue, which takes place when weather conditions are hot and windy, or the tree does not get enough water.

Crimson King maple trees can become infected by aphids, soft-bodied insects that suck the sap of the stems and leaves. A serious infestation can cause the leaves to drop. Another occasional problem is scale, most commonly cottony maple scale, named after the cotton-like mass formed by the insect on the underside of the branches. A Crimson King maple tree that is not thriving can also suffer from borers.

If the Crimson King maple is seriously infected, it probably cannot be saved. If the tree is only lightly infected, fertilizing with high nitrogen fertilizer and pruning may revive it. The removal of girdling roots can be harmful to the tree as the roots are functional, and should be followed up with fertilization. Watering will help scorched trees, provided this is not due to a diseased root network. The best solution for aphids is spraying; alternatively, predatory insects may sort the problem out for you. Horticultural oil sprays control scales. Keeping the tree healthy will help control borers: Identification and proper application of insecticides are key.

Drought leads to decline and occasionally physiological leaf scorch, which appears as marginally browning during the summer. Water young trees frequently throughout the first growing season. Slow, deep watering is best, such as done with a drip or soaking hose. Keep the soil moist and cool until fall arrives. Established trees are moderately drought-tolerant and only need supplemental watering during long, hot, and dry periods. Mulching trees, especially when young will aid in conserving soil moisture.

Conclusion/Recommendation

I think the problem is physiological leaf scorch.

I also recommend for a more accurate diagnosis that you send a leaf sample to MSU Plant & Pest Diagnostics - For details and instructions go to this link: https://www.canr.msu.edu/pestid/

Reference resources:

http://hort.ufl.edu/database/documents/pdf/tree_fact_sheets/aceplae.pdf

https://www.canr.msu.edu/uploads/files/SmartTreeSelections/NorwayMaple-AltTrees.pdf

https://web.extension.illinois.edu/hortanswers/detailProblem.cfm?PathogenID=26

https://plantfacts.osu.edu/pdf/0246-20.pdf