There isn’t enough info to really suggest a solution although I can say that sprinkling ammonia around isn’t a good idea. Get a dog and cat repellent. Bring photos and sample of the plant to the garden center for them to take a look. Piling mulch up around the stems and trunks of shrubs and trees is the most common reason for shrub death. Get under your shrubs and brush back the mulch until you see to original soil that the plant came in and keep it at the level.