I have a two year old Mexican lime tree, grown from seed, that has been in good health until two weeks ago when it started dropping its leaves. It has less than 10% of its leaves remaining. The tree is about 2 feet tall and has a bout a 3/4" diameter trunk. It currently resides in a 14" pot. I checked the roots and found them filling the bottom 4 inches of the previous pot. They didn't smell bad or have any white growths, so I didn't suspect root rot. I gently broke the roots up a bit and moved it to a larger pot with some fresh cactus/citrus potting soil for good drainage. I think the previous soil may have held too much water. This time I planted it a bit higher and shallower in the pot with some roots near the surface. two weeks later it was still dropping leaves. It is down to about 10% of its leaves. The leaves start to turn yellow in some regions and then the yellow areas turn brown, the remainder of the leaf is still lush green. Shortly after, the leaves fall off. I would guess that it was not getting enough water to the leaves and is dropping leaves to compensate for the lack of hydration. The house is 70-75 degrees throughout the day and the soil temperature is about 70F. I put a humidifier near near the tree to help get some water to the leaves, even if the trunk supply is not function properly. It has slowed the defoliation, but has not stopped it. Today I noticed a wet spongy region banding the tree's trunk just above the root. The band is at the height of the soil before re-potting. I am guessing that is some type of fungus or other infection. I have not been able to make a good diagnosis from information online. I have attached some photos of the affected area. Does anyone know what the problem may be and what treatments are available? Thanks, -Eric
It has been a few weeks now since I started this thread. I figured I would give an update. After some good discussion with Kent Stiffler of the Penn State Ag Extension Office, It was determined that there was little to do for the tree but wait it out. The plant pathology lab on campus was very nice to offer assistance, but warned against transporting such a weak tree in this cold weather. Changing to a better draining soil (Miracle Grow Cactus and Citrus Soil) and maintaining a root temperature of at least 65F has been good for the tree. At one point it had only 20 leaves remaining, but is now budding everywhere and on the up swing. The wet area on the trunk seems to have healed itself. Kent mentioned that he had seen a similar symptom with trees that had trunk protectors on too long. For my tree, it was probably due to the soil being too high on the trunk. I hope this update will be useful to someone. -Eric
If a build up of mosture was the problem maybe the addition of more perilite in the top few inches of the soil would provide proper drainage to the roots. I used expanded shale instead of perilite through out the whole soil, but the suggested use written on the side of the bag is to add it to the top of the soil and till it in. Not only providing proper drainage this might prevent further soggy stem sendrome. I don't know what i would personally do if i had it to do over again. The shale works nice, but in my recent adventures in mixing soil i am starting to think that something less intruding on my root space would be nice. Same goes for compost, big chucks of manure not properly decomposed just occupy valuable root space.
