Answer: The pale yellow leaves you describe indicate your oak tree is not getting the nutrients it craves. If you haven't fertilized, it's time to feed your tree. If you have recently fertilized, the yellowing leaves may indicate poorly draining soil or soil with a high pH, which can bind up nutrients and make them unavailable to your tree's roots. If you don't know what your soil pH is, I'd recommend having it tested so you know what you're looking for.
Japanese maple leaves can develop leaf scorch (brown, crispy margins), from over exposure to afternoon sunshine, too much fertilizer, wind burn, poorly draining soils, or salt build up in the soil. Again, have your soil tested, and when you water your trees, flood the soil to help leach out accumulated salts.
Hope the above info helps you determine just what might be causing the distress in your maples and oak tree.
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