Please help identify/Save 'Lemon' Tree

[mrlongfellow]

Hello. My wife and I recently moved into a new home and we are having difficulty identifying our backyard tree. There is a gardening tag at the bottom that states 'Eureka Lemon' but this tree has large thorns which is not a characteristic. The fruit is larger than any lemon I've seen and looks more like a grapefruit. The previous tenant said it was a lemon tree?

Also, the tree seems to have some problems, possibly disease: Sap oozing from the bottom of fruit, small brown bumps all over the trunk and branches and finally ants crawling limb to limb.

I would really appreciate any help we would like to save this tree if possible. Thanx in advance!!

Full view:
[img]https://farm3.static.flickr.com/2707/4095868865_03db2a6dc2.jpg[/img]

Example of fruit (Ignore the toy):
[img]https://farm3.static.flickr.com/2729/4096628712_6874580b2e.jpg[/img]

Thorny trunk:
[img]https://farm3.static.flickr.com/2509/4096628130_f1e3dbb30f.jpg[/img]

Are these brown bumps a sign of disease?:
[img]https://farm3.static.flickr.com/2768/4096653000_c0a166c97a.jpg[/img]

Oozing lemon another sign of disease?:
[img]https://farm3.static.flickr.com/2537/4095868949_59303b5ebc.jpg[/img]

Finally, a shot of the fruit cut in half:
[img]https://farm3.static.flickr.com/2679/4096653134_39c59f3c83.jpg[/img]

[Kisal]

The brown bumps are probably scale insects, which can be a serious problem of citrus trees. The ants are attracted by the honeydew secreted by the scale.

This page may offer you some helpful information about the control of scale on citrus:

https://www.ipm.ucdavis.edu/PMG/r107301311.html

[mrlongfellow]

Sounds bad, the tree is pretty infested with scale. Thank you for the information, I am looking forward to looking at the tree in the light tomorrow and trying to find a solution. Thanx!!

[applestar]

Since you've cut a fruit open, I would think the you should be able to identify the citrus by it's scent -- Lemon or Grapefruit? It DOES look very round and not lemon-like at all, certainly not 'Eureka' which I'm pretty sure are the kind you usually find at grocery stores. If it IS lemon, could it be 'Ponderosa'?

I guess another possibility is that this was originally a grafted 'Eureka' lemon, the top died down, and what you have now is the root stock growing. If the fruit tastes good, you could still use them for lemonade, etc. (Peel the skin off first since the thick spongy part will absorb a lot of the juice)

I don't know anything about grafting citrus, but one recourse might be to study the technique (local backyard fruit growers or citrus growers society, etc.) and try grafting desirable varieties on to this tree....

ETA: Looking around for more info about citrus rootstocks, I came across this [url=https://www.ultimatecitrus.com/pdf/tncitrus.htm]webpage on citrus propagation[/url]. It's a Florida-based site so you have to keep the differences in mind, but some interesting info there.

[mrlongfellow]

Thanks for all the info! With some help, I have a theory that the rootstock has overtaken the Eureka lemon. The previous tenants lived here quite some time and I don't think they paid any attention to the tree. I think what I need to do is attempt to remove everything below the graft line (leaving a much smaller tree) and hopefully the Eureka can survive! Here's a pic of the tree base where you can see the Eureka splits to the right and the rootstock to the left. There are only thorns on the rootstock:

[img]https://farm3.static.flickr.com/2798/4098831180_06dd0e8588.jpg[/img]

[applestar]

I think you have it!
I hope someone can advise you on best pruning schedule. They do say, though that you shouldn't cut more than 1/3 of a branch or the entire plant at a time.

I'm thinking that for starters, you could save yourself some trouble and trim off part or all of those scale infested branches.

[herchelle]

When I looked at the cut up fruit, my first thought was pomelo (Citrus maxima or Citrus grandis). I have no experience growing them as I live in zone 3 ( southern Alberta Canada) but my good friend from Vietnam is always sharing these with my family.