Answer: Wow! What an interesting series of questions! First, the maple tree. If you can get a close look at the leaves and find the red coloration is red, you've got maple gall. These are tiny insects that pierce a hole in the leaf and exude a substance that causes the leaf tissue to become hard and red. They won't hurt your tree and elimination is difficult because chemical sprays cannot penetrate the galls. I'd just leave them alone. As for the blueberries, I think the plastic bag trick excluded enough oxygen and included enough heat and humidity to defoliate your shrub. A healthy shrub will replace the lost leaves so just give it some time to recover. Anything but plastic can be used to keep birds away from the fruit - an old sheet or tablecloth would have been much better for your plant! Yellowing leaves on a quince isn't anything to be concerned about. Quince will drop its lower leaves as it produces new growth. As long as the plant looks otherwise healthy, don't be concerned about the falling leaves. As for your holly, since it is an evergreen it will retain its leaves for 3-4 years but after that amount of time evergreens shed their oldest leaves in favor of replacing them with healthy new leaves. Springtime is a natural time for this to happen. Finally, the rhodie problem. Many things can cause leaves and branches to turn brown; fungal infections, root rot (from poorly draining soils), and high soil pH are the most common reasons. Transplant shock is another possibility. At this point I'd just continue to give the plant good care and see how the new growth comes out later this summer. If it is still failing to thrive by the end of summer, dig it up and inspect the root system and planting hole. Add some organic matter if the soil isn't draining well and then replant and water well to help settle the soil.
Best wishes with your landscape!
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