Answer: While dry soil or (now) overly wet soil could cause the plant to wilt and curl as you described, there is also a possibility that a latent infection has reappeared or a new one taken hold since the plant has been stressed. These are difficult to diagnose long distance. I would suggest you take a sample and possibly a photo of the overall plant to your county extension or to professionally trained nursery staff for a definite identification of the problem.
In the meantime, these plants are shallow rooted and very sensitive to both over and underwatering. Their roots must have a humusy, evenly moist, yet well drained soil. This means watering to supplement rain as needed to keep the top six inches of soil moist but not sopping wet. Using several inches of organic mulch will help keep the soil more evenly moist between waterings. Do not apply a deeper mulch layer as this will cause the plants to try to root upward into the mulch layer search of air and cause more problems in the long run.
To know if and when to water, dig down with your finger and see. As a guide to how much to water at a time, water what you think is about right, then wait a few hours, then dig down and see how effective your watering was -- it can be surprising.
Good luck with your shrubs!
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