indoor orange tree

Question

I have an orange tree about 8 years old. I keep it outside in the summer and bring it in when our temps start to drop. I live in Illinois. After bringing it in the plant was very healthy. I noticed the leaves started to drop off but they have almost stopped dropping off. However, I now see on the bark of the plant white lines and they are spreading all over the bark. The leaves still look good. The plant fell down during a storm and one of the branches split a little. It did not split all the way down so I wrapped string around it to keep it from splitting any further. My concern it the white lines on the bark. You can actually see it spread the tops of the branches are a healthy green and as you get closer to the middle of the tree the white lines appear. The whole trunk has these lines on it. Is my tree infected with something? I hope its not dying but, I’m really concerned. As recently as Sunday when I watered it the tree, it was fine all the branches were all a nice color green. could the split in the branch have anything to do with the white lines? Can you tell me what is happening and how do I fix the problem. Please keep in mind I have the tree in my townhome so a spraying of the tree with anything is a problem as I can’t move it outside and its too cold and the tree is quite large to move around. Any solution to my problem would be appreciated Thank you

Answer 1

Citrus trees usually have white or greenish white wood, so it could be that the bark is splitting and the wood is showing through. Causes of bark splitting include sunburn (which can be prevented by painting the trunk white), previous exposure to frost, or diseases like Phytophthora, which mostly cause other problems as well, as seen on this page:
http://ipm.ucanr.edu/PMG/C107/m107bptrunkrootdis.html

Or if the white lines look more like something growing on the trunk, this could be Armilleria infection, a damaging fungus that causes root rot. Although this is a picture of Armilleria on an oak tree, it would look similar on a citrus:
http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=10583
However, it doesn’t sound like your tree has the other symptoms listed in this article:
http://ipm.ucanr.edu/PMG/r107100311.html

It’s possible that a disease could have come in through the broken branch. If you can’t figure out the cause, you may want to have an arborist or extension agent look at the tree.

Lichens and scale insects can live on citrus trunks, but these would cause white patches or speckling, not lines.