Is this winter leaf drop? The leaves aren't yellow so I don't think its Magnesium deficiency but I watered it with Epsom Salts nonetheless at 1 tbs per gallon. The petiloles are still left on the tree after the leaves fall and I read here that it could be due to stress. Its a Tarocco blood orange and I transplanted it into CHC/peat moss, 3:1 several weeks ago and it seemed to have done fine. Also the whole scions that I grafted on them a month or so ago that sprouted have now died off. The temps on the cold side have been in the low 50's and upper 40's but it still gets really warm here as today hit 80.

The key to WLD is exposure to direct sun while the roots are cool--generally anything below the low 60s. Roots are completely non-functional at 55 F, but have very low ability to uptake water below 60.

To stop WLD either remove the tree's foliage from the direct rays of the sun, or insure that the tree's root zone temperature is at or above 64F. If leaves continue to drop, raise the container's temperature up to 70F. Don't rely on the room temperature, as the temperature of the growth medium will always be cooler than the room/air temperature due to evaporation. Anyone growing a container citrus tree NEEDS to have a soil thermometer, to be successful. WLD is usually worse following a bright sunny day. NOTE: when the nights are cold, followed by a bright sunny day, the foliage heats up quickly, while the growth medium remains cold for an extended period of time, therefore the root system cannot supply the needed water to cool the tree's foliage. For the tree to get back into balance it has no other option but to discard it leaves. - Millet (1,147-)

Judging from the way the leaves are curling they do not have enough water. WLD growing conditions is one of the possible causes. It could also be that the tree just needs to be watered more thoroughly or it could be root damage.

Looking at your pictures, the leaf curl does not seem to be all that unusual. I do notice quite a few leaves laying on the CHC surface. However, whether it is WLD or not, depends on how much time has it taken for that amount of dropped leaves to accumulate. In WLD, the leaf drop becomes excessive, and when the tree is shaken a good amount of leaves will drop. As your medium is 3:1 CHC to peat moss, it cannot be over watered. If you believe the cause might be under watering, then soak the entire container in a larger bucket of water, (with or without fertilizer), for 10 to 15 minutes. Even if you leave a 4:1 or a 3:1 CHC peat medium in the water over night, the tree's roots system will be fine, without any problems what so ever. Remember, it is not the water that causes problems, it is the lack of oxygen that damages or kills the roots. With a medium containing the amount of aeration as a CHC medium has, sometimes the irrigation water passes through the chips so quickly that it does not have time to soak into the chip. Therefore, a good soak every now and them is very beneficial. A coconut chip can absorb 7 times its weight in water, when given proper irrigation.. Lastly, if seriously doubt that your tree has root damage, due to the fact it is in a CHC medium. - Millet (1,148-)

And if you are going to follow Millet's advice above, use warm water (~80 F).

Barbara

Its hard for me to understand since I transplanted four trees at roughly the same time. The Tarocco and the Meyer are suffering the leaf drop while the Owari Satsuma and the Oro Blanco are not. The only difference is the Tarocco and the Meyer are about two feet higher off the ground than the other two, which are all on grates. They are in 15 gallon Smart Pots. I don't have another container big enough to submerge the pots so I usually water until it runs through, and then some. I must admit I have been watering less frequently thinking they don't need as much water during the fall and knowing that CHC holds water really well.