We can consult with our plant pathologist about the turtlehead once he returns from a horticulture conference, but the spicebush symptoms appear to be abiotic (that is, not caused by a pest or disease). You mention it was wilting...was it watered at that point (either by hand or from rain)? Has it been regularly checked for watering needs after it was planted? If not, perhaps the roots are struggling to establish and are more easily stressed by drought. The leaf damage does appear to be caused by desiccation and not an infection. Yellowed leaves might still fall off, even if a stress on the plant eases, so expect that the plant might appear to decline further even if it is stabilizing. New foliage might not appear until next spring.

For the turtlehead, since they like to remain more evenly moist, continue to monitor them for watering needs so the roots don't get too dry for too long. Leaf spots on a variety of perennials, fungal and bacterial, can be quite common but fortunately few are serious. If the plant's leaves are wet when watering (say, with a sprinkler), that can increase its vulnerability to infection, so try to only wet the soil around its roots when irrigating if possible, or water early enough in the day so foliage can dry by nightfall. Make sure the mulch isn't touching the plant's stem bases since this hampers air circulation around the soil surface next to the stems, which raises the risk of infection by Southern Blight or other fungi. (This specific disease is not suspect currently based on the symptoms pictured, but it's a precaution to keep in mind.)

Miri

Our plant pathologist thinks the leaf spot on the Turtlehead might be bacterial, but we can't be certain as the symptoms aren't too dissimilar from other causes of leaf damage. The browned spent flowers might be Botrytis, though that is a very common and usually non-serious fungal infection as it predominantly rots dead flowers or foliage in that case. For now, just remove any blotched leaves and dispose of them and monitor the plant for watering needs to keep the roots vigorous. Even if a fungicide spray were to be effective, which it likely would not be at this point, we'd discourage treating a plant popular with pollinators since fungicides can potentially harm other organisms.

Miri

You're welcome.