Curious striations on avocado sapling trunk...?
I started growing an avocado tree from a pit...it's at least 8 months old now. My roommate said it was important to nip off some of the top shoots so that it would get stronger lower leaves. After it got about 20 inches tall, we nipped off the top, and now a few weeks later the top half of the trunk is showing signs of what I can only assume is infection.
The bottom of the stalk/trunk is quite strong and stiff - as are the 6 or so leaves coming from it. Above that, where the newer leaves are, the stalk is mottled with 2-5mm long dark spots running vertically, and all the leaves in the area with the spots are paper thin, slightly translucent, and very weak. On top of them they have a waxy shiny sheen, where the healthy leaves do not. The healthy leaves are quite erect sideways, opaque, and vibrant dark green - while the weaker leaves droop almost vertical, are translucent, and lighter in colour.
Is it an infection? Is there anything I need to worry about? Is there anything I can actually do?
1) Good bottom 1/3 section
2) mottled middle 1/3 section
3) mottled top 1/3 section