The deceased azalea has been treated to the same soil, watering and fertilization for all of the six years I've had it. No problems in that time. Things started going south with the vinegar ph balancing regime. Further research gives me the impression that the heavy Miracle Gro treatment I use tends the acidify the soil on an ongoing basis, so there in no need for MORE acidity. Can I prove beyond a doubt any of this? Nope. Just a hunch from collecting 200 trees of 30 different species for 9 years.