I have 50, ten year old eucalyptus trees. The are about 60 feet tall. The problem is that they use to grow very slowly, apart that a big amount of leaves used to fall without replacing new leaves. I use to water the trees with a large amount of water, especially in summer, and use to give them fertilizer high in nitrogen (30-2-2). Last year I made a soil test resulting that that the soil is high in nitrogen and phosphorus and with soil high in pH (between 9 and 10). I thought that this was the main problem, so I began using vitriol fertilizer (a fertilizer which is used to control pH in soil) because, as you know, soil high in pH will not let fertilizer get up in the tree. But the trees are still not growing at all. Do you think if I inject some sort of fertilizer directly in the trunk of the tree, this will help? Can you please help?
I do not know of an injections type fertilizer.
You may want to refer to a professional arborist.