I have about a 3-1/2 to 4-foot avocado started from a seed. It sits outside and was doing very well until recently. (I live in South Florida by the way).

It is still sprouting new leaves at the top, but almost as soon as the leaves get of any size, the begin turning yellow from the middle out, and then the yellow areas begin turning a dark brown.

I am a novice plant grower and I don't know if this is some kind of pest, a fungus or an environment problem. I water it well when the soil is dry and it full sunlight probably about half the day.

If someone can help me figure out what's wrong and what I can do to fix it, I sure would appreciate it.