please help me diagnose! here is what i can tell you:

a citrus nursery planted this Meyer Lemon tree (i think it was a 15 or 20 gallon at the time) for me last May; i usually have people do the planting because i know that citrus is susceptible to foot rot and i want to have the experts do the planting.

a couple of months ago i started noticing this hole developing at the base of the trunk; i had the nursery come out to take a look at it and they said it was an injury (mind you, i do not own a weedwhacker nor done anything to possibly injure the tree; bascally i water and fertilize and remove organic matter near the trunk, that's it). they said it would heal up and it would be OK and not to worry

it could be my imagination but the hole is getting gradually bigger

in the meantime the tree flowered nicely last month and now has loads of fruit

some of the leaves are splotchy yellow but i did not worry too much about that b/c i thought it could be old leaves, yellowing due to fruiting/weather/fertilizer, etc.

however last night i did a bunch of Googling and i saw pix and info. about something called citrus collar rot. does anyone know whether my tree has this???? and is this something that could be contagious to my other citrus trees?

here's the photos:

http://www.flickr.com/photos/61875512@N07/