These 3 trees suffered pretty miserably under the “care” given by our tenants. The tenants hired a gardener who used a weed-whacker to keep the grass down with the nasty result that our trees were all ring barked. Several died. But these three: cherry, olive, mango all survived. After over 3 years in the ground the cherry and olive are both about hip height. The mango is about head height. Maybe a couple of years without ring barking will see them thrive.
Laura Rittenhouse's Gardening Journal 
Anyone who rings a tree with a weed-whacker cannot be called a gardener.
Get this, the woman said she has a friend who is an arborist and he said the reason th trees were dying is there is a large old native that is dying and sucking all the nutrients from the soil. I almost called her and asked for his number so I could give him a lesson in tree care.