Help me save my Glenn mango tree!
I'm a novice backyard mango and avocado grower in South Florida. I planted four mango trees (Glenn, Keitt, Carrie and Pickering) back in early February this year and they were doing fine until two weeks ago the Glenn started having some trouble.
The Glenn was doing fine, it's probably 5ft tall and it actually did set some fruit this season. It was carrying 8 fruits until two weeks ago. In hindsight I probably should have cut the flowers and tip it for growth, but I was too excited with the possibility of fruit the first year. I have been spraying every 10 days or so with neem and spinosad and more recently added kelp to my foliar spray. I've had some insect issues back there, I think some whitefly, but I was trying to fight it organically.
Then two weeks ago the leaves started browning and a lot of them are actually fell off, fruit also dropped and I'm down to just two fruits left. Our soils in Broward close to the ocean are very sandy after a thin layer of top soil that's been added for gardening. This tree is a little shaded in summer mornings until past noon by a well established coconut palm that's maybe 9 feet east of it, but gets direct sunlight until sundown. It may be fighting its roots too?
Anyway, I'm posting a picture here and I'll add a couple more to see if anyone can help. I'm completely lost, and I don't know if I'm fighting a pest, a fungus, or just overdoing it with the sprays...