The answer to 'why is my shrub dead trees' is that there are several common causes for a dead shrub, including drought, disease, pest infestations, or improper planting and care. Symptoms may include wilting, discolored or dropping leaves, and brittle or decaying branches.
To troubleshoot, first check the shrub's soil moisture - it may need more frequent watering, especially during hot, dry spells. Inspect for signs of disease or pest damage, and prune away any affected areas. Make sure the shrub is planted in the right spot with the proper sunlight and drainage. If the problem persists, it's best to consult a professional landscaper or arborist to diagnose and treat the issue.