Question
Hi Darlene,

I used to live in Fort Wayne, 95-98.  I taught music at IPFW!

Now, I live in Beirut, Lebanon, eastern Mediterranean coast.  Climate is similar to California.

I have an orange and a lemon tree in pots on my terrace.  They thrived for two years and more, but this summer, the orange shot up a thorny spike, and since then, both trees have yellowed, and dropped leaves.

Do you think they are root bound?  They have not grown a lot in their big pots over the years.

What do you think?  

Merry Christmas, Happy New Year, and greetings to the Fort!
best, Paul

Answer
Paul,

Do they get lots of sun all day long? Citrus trees need lots of sun. I assume that the trees are both in pots with drainage holes and a drain tray underneath. How often do you water them? Do you leave water standing in the drain trays under the trees for long periods of times. Do you fertilize the trees?

I suspect that you have grafted trees. The graft where the 2 parts of the tree were joined is probably at the base of the tree just above ground level. In other words the root stock is one variety and the trunk and top of the tree is a different variety. The roots would be a very sturdy old variety that was very thorny and did not produce good fruit but supported the tree well and lived forever. The top would be from a variety now to be very well flowering and fruiting but that does not grow sturdy roots so they graft the 2 varieties together for the  best of both worlds.  This thorny spike that the orange sent up may be coming off the root stock and be threatening to take all the nourishment from the orange that you want to grow on top. If it were mine I would prune that thorny spike back to it's base and try to keep it pruned in hopes that soon the orange top will take over again. Be careful not to overwater either tree, so you don't get root rot on top of your current problems. I would reccommend fertilizing with a citruc tree fertilizer once a month.
good luc.

Darlene