Thorns on Cara Cara?

[Isaac-1]

I live in zone 8b in Louisiana and planted a Cara Cara orange tree a couple of years ago, and while I was outside covering it to protect it from the early season freeze we had last week I found that it has started growing thorns on all of its branches.  It has not reverted to root stock, leaves are still the same style as previously, overall size is now about 6 ft tall, which is on par with an Armstrong Satsuma that I planted nearby at about the same time.

My concern is that the entire tree may now be a sport as in my limited reading on the subject Cara Cara is somewhat prone to mutation / reverting to a plain navel variety, and there is a note in the CCPP file that Cara Cara budwood should only be supplied from trees that have fruited to prevent this issue.

Has anyone experienced this issue with Cara Cara or Navel Oranges in general?

Should I consider re-planting another Cara Cara?  I have limited sheltered space available to plant non-cold hardy citrus, maybe room for 2 more cold tender varieties close enough to the house to provide lights for heat, etc., and I was already thinking about planting a Chandler Pomelo in one of those spaces.

p.s. This is definitely not rootstock taking over, leaves are definitely citrus, root stock is a trifoliate hybrid (Carrizo)

[Millet]

Do you know for absolutely sure that your Cara Cara tree is grafted upon Carrizo?  Do you know where the graft line is on your tree?  Is there any growth what so ever below the graft line?

[Isaac-1]

I know with certainty that it is grafted on some type of trifoliata based on removal of growth below the graft line in the 2 years since I planted it.  Also based on email with the nursery that grew it, the exact root stock is claimed to be Carrizo, though the exact Citrange may be anyones guess.  The leaves on the tree look correct for a navel orange with winged petioles, though I am no expert at citrus identification by leaf shape, so since it has yet to produce any fruit, it is possible that it may be some other citrus with similar leaf shape that also commonly has thorns.  Though overall the thing that strikes me as odd is that the thorns are a new thing as they almost were certainly not there when I was covering it during freezes the last 2 years, either that or I got very lucky, since I stuck myself with them at least 3 or 4 times while covering and uncovering last week, which is probably the 5th or 6th time since planting it 2 years ago.

Ike

p.s. one note on the thorns they are much shorter than the thorns typically seen on Carrizo (which in my experience has nasty looking long thorns).

[Isaac-1]

We finally had sunshine today, so I snapped a photo of the supposed Cara Cara leaves showing the small thorns.  Perhaps someone that is better at leaf identification can confirm what this is, to me it looks like the textbook example of Cara Cara, though personally I can't tell the difference in leaves between Cara Cara, Washington Navel, and Dancy Tangerine in online leaf photos.  I am starting to think this may be mismarked Dancy as the nursery this tree came from also sells Dancy Tangerines, which seem to have very similar leaves, and are noted as being somewhat thorny, though I can't seem to find an image showing leaves and thorns together.

 

[Coach62]

I'll double check today, but I believe my Cara has thorns. The tree is an excellent producer of very high quality, low acid fruit.

[Coach62]

I'll double check today, but I believe my Cara has thorns. The tree is an excellent producer of very high quality, low acid fruit.

OK - looked at both of my Caras, one older, one only 4.5' tall.  Both are consistent, both give great fruit.

Older woody growth = no thorns.
New flush growth = no thorns.
Older green sticks = thorns.

I had never paid much attention before, it appears that before they make the transition from older green sticks to woody branches, they grow, then drop the thorns.  Again, both of mine are Cara Caras.