My Lisbon lemon tree has been oozing sap from the lower trunk for about two months. The bleeding is heaviest in the first 2-3", lessens above that, and ends 9" above the soil line. The sap has a clear amber color. The trunk is about 3/4" in diameter and looks healthy if not for the sap. The leaves have lightened in color and have acquired a hint of yellow. There is no new growth unlike on my other trees.

This problem is very similar to the one described in this thread in an external forum in which Millet noted that it's not an uncommon occurrence. The tree needs to be repotted but I'm worried about the possibility of the condition spreading to my other trees through the handling.

Have you encountered this condition before? What action, if any, did you take? What was the outcome?

Try googling for 'gummosis' which is one symptom of attack by Phytophthora. This could be your problem, although most descriptions say there is also bark damage.
Phytophthora, which also causes foot rot at soil level, can be controlled using fosetyl-Al, sold under the name Aliette. See
http://www.bayercropscienceus.com/products/view:aliette/?p=
I have had to buy this in France as it is not sold in the UK. It has certainly halted the spread of foot rot on a couple of potted citrus that I thought were unlikely to survive.
Mike (aka Citrange)

Junglekeeper, This is what Texas A&M has to say about sap forming on the trunk of citrus trees. I list the Universities advice and also their web site. The web site list most all common citrus diseases, their cause, and what to do about them.


http://aggie-horticulture.tamu.edu/extension/homefruit/citrus/table2.html

2. Hardened gum exudate on bark of trunk or limbs -- anytime -- gummosis -- Follow good cultural practices, no control, not usually life-threatening

Millet

Thanks for the replies. My first thought was gummosis as well but Millet, you pointed out in the other thread that it may not be - giving me some hope. Do you think it's gummosis based on my description?

Mike, the products you mentioned may be hard to come by here. In any case I'm hesitant to use such chemicals on my trees as I intend on eating the fruit.

At this point the condition doesn't look too bad. I removed almost all the sap from the trunk and swabbed it down with alcohol. When I peeled off sections of the sap some of the thin, dry layer of bark came off revealing the green underneath; the damage appears to be very light. As of today there is only one point of leakage left. I'm waiting for signs of improvement in the color of the leaves. The roots look healthy. The only thing that may have looked out of the ordinary were the large number of colonies of fungi with tiny, white spores the size of grains of sand in the soil.

I'm not sure how to proceed even if the tree stops bleeding. I'm wondering if it should be disposed of along with the soil and the container to prevent spreading the problem to the other trees. The Texas A&M document suggests living with it. What would you do?

Mike,
Are you not worried that your trees, even though they have been successfully treated, still harbor the fungus - if not in the tree then in the soil?

I understand your reluctance to use systemic chemicals on fruiting trees, although this product does seem to be widely used in US agriculture.
As it happens, of my two trees affected one was a Rough Lemon and the other a not-yet-fruiting seedling. So no edible product from them. In both cases, I also re-potted from the original soil based mix into a peat/CHC mix and raised the plants slightly to avoid dampness at the trunk base.

Junglekeeper, If it was my tree I would keep an eye on it, but would not worry about it all that much. Here is what it says on page 553 of "The Citrus Industry Volume 2."

>>>>>>>>One of the most common effects of bark diseases, especially diseases of the trunk, main branches, and upper part of the main roots, is to stimulate gum formation, and this has led to the use, by growers, of the general term "gum disease." Exuded gum is one of the most conspicuous features, and one of the first noticeable symptoms, of several bark diseases; but gum formation itself is NOT A SERIOUS HANDICAP TO THE TREE unless the bark dies or the gum plugs the wood vessels. The gum is merely a resultant, and may sometimes serve A USEFUL PURPOSE IN FLOODING THE TISSUE AHEAD OF CERTAIN INVADING PARASITES AND SLOWING DOWN THEIR PROGRESS. Frequently, gum forms near the cambium under the live bark for considerable distances, six inches to a foot or more, beyond the margin of the tissue actually invaded. The presence of exuded gum alone is not a good diagnostic character, since its appearance and form are usually much the same IN A LARGE NUMBER of different diseases and its amount depends on a number of external and internal factors such as temperature, air humidity, physiological conditions of the tissue, etc. Gum formation is not always due to the stimulus produced by invading organisms, but may result from irritations of chemical or other stimuli.** Where organisms are not involved, the gum formation is usually temporary, but may frequently be mistaken for that produced by invasion of organisms<<<<<<<

** J.M. Wallace has shown that merely removing a few of the outermost layers of bark suffices to destroy the stimulus to gum formation.

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Junglekeeper, because gum is nature's method of protecting the tree, as stated in the article above, I don't think I would keep removing the gum from the tree. By removing the natural protection of gum, you could be prolonging the tree's ability to cure itself.


Millet
Anton von Leeuwenhoek
First found Polyembryony in oranges. (1719)

Thanks for the excerpt, Millet. I removed the sap for three reasons: 1. To determine which and how many of the points of leakage were still active; 2. To keep the trunk clear and dry (I thought the moisture from the sap might create a problem for any unaffected bark underneath); 3. To stop the leaked sap from pooling around the base of the trunk (there was quite a bit of it). I'll certainly take your thoughts into consideration. So it appears the tree is not quite ready for the dustbin.