hello everyone,

could anybody identify and let me know what this is? it's yellow in color, pretty hard, and also many leaves started to drop! at a rate of about two leaves per day. i trimmed the tree significantly about a month ago and have not given it much fertilizer since wintertime. it stays in my room at around 68-70 degrees and does not receive a whole lot sunshine.

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Looks like Citrus Phytophthora foot rot or Gummosis.
You can treat it with Alliete.

Yes it does.

It is collar chancre. It is a form of phytophthora attack.
You must treat your plant with Aliette (Fosetyl-Al), scrape clean the chancre and put copper sulfate on it.
If you do it now, it's OK. If you wait too long you plant will die.

so why does it happen? how do i prevent it?

It's a soil pathogen. I would suggest you repot now, using a steril potting mix, taking care to rinse the roots, rinse out the inside of the pot well with a 1:10 bleach solution, and then treat with Aliette (Fosetyl-Al) (if you can find it in small amounts, it is a commercial product). If you cannot find Aliette, you can use Agri-Fos, which is the same thing, and available on amazon.com or at your high end garden centers. You will still be transferring the organism to your new pot, but you'll have significantly reduced pathogen pressure, and the phosphorus acid will get rid of whatever leftover phytophthora is left. Here is a link to the product:

http://www.montereylawngarden.com/pdf/agri_fos_systemic_fungicide_suppl01.pdf


From Patty, sadly the "Phytophthora Queen"

Keeping the soil too wet & cold. Also what rootstock is it on?

This is the most common copper you will find here in the states.

I have mixed a copper based fungicide with Latex paint, and painted the trunk about a foot up the tree, after removing the damaged (but not live) bark, and washing the affected area down with a copper solution. I believe painting the wound is good a preventative measure when the trunk receives any sort of damage at ground level that breaks the bark.

I have the same problem with my limequat . We don't have alliette here. What other fungicides could help here? Or does it maybe come under another name?

Evaldas, look for something that contains Aluminum tris (O-ethyl phosphonate) or you can also try Phosphorous Acid. Both are extremely effective against Phytophothora. These are the two respective ingedients in Aliette or Agri-Fos.

Is it contagious?

No, not tree to tree. It is a soil pathogen.

Are you supposed to spray Aliette or irrigate with the solution, since you want it to take effect on the roots?
I've found another product with fosetyl-al in it, that says to water against Phytophtora, because I don't think I'll be able to find the actual Aliette here.

You can either use it as a foliar spray or a soil soak. Same with AgriFos.

Also, when you remove the sap, how concentrated should the copper sulphate solution be? Best would be if you can tell me intense the blue colour should be , because I think I'm just going to make a small amount and then using a paint brush apply it on the trunk.