Hello, I have two large lemon trees, about 6 ft tall, as well as many small tangerines, key limes and pummellos. I am growing them indoors under direct light from T8 fluorescents, with almost no natural light. My concern is for one of my lemons: a year ago it came down with a terrible disease, which i could not, for the life of me, diagnose. Finally i discovered it was "citrus greasy spot" Which i then eradicated with a copper spray. By this time, however, it had already afflicted nearly 90% of the leaves. The leaves have all recently gotten to a point of weakness where all of the diseased leaves have fallen, leaving the tree very barren, and the new growth is very slow, and focused only on the ends of the branches, not in the middle of the tree, where it needs it most. I do not want the tree to get any wider, or "leggier" but to fill in where it lost all of its leaves, and remain rather bushy. My other lemon seems to do this on its own very well. Does anyone have any advise for helping this tree? Again, it has new growth, just very slow and in the "wrong" places. Also, i have noticed on my other lemon, and a few tangerines, some of the newest leaves have remained very small, too small for citrus. I'm wondering, could that be caused by over fertilizing? I am certain no bugs or fungi are currently attacking any of these trees. I'm currently using miracle-grow 30-10-10, twice a month or so. I don't have a camera, but may be able to borrow one to post pics. We'll see. Thanks in advance for advice!
anyone have any thoughts as to whether i should prune it back, or if i should let it do its own thing?
Because your trees are seedlings, you should not prune back if you wish the trees to eventually bear fruit. I am not surprised that the lemon has not yet begun to fill in the bear spots on the branches, as you live in Maine. However, as we get closer to spring, the tree should begin to flush a lot of new growth. In your area, you might see the beginning of new growth sometime next month. Lastly, I am also surprised that your tree had greasy spot, as your trees are not located in a citrus producing area. Normally, container trees in northern climates rarely, if ever, get many of the diseases that commonly attack commercial groves trees, simply because of their location. The major source of inoculum for greasy spot is ascospores that are produced in decomposing fallen leaves that have earlier fallen from the tree. They are discharged within a few minutes when the leaves are wetted by rain, or irrigation. Greasy spot is primarily a defoliation disease. The availability of the ascospores depends on the length of time from leaf fall, rate of leaf decay, and the rate of development of the pseudothecia. Whatever, your tree had, you must be grateful that the fungicide you sprayed cured the problem. Copper based fungicides are a good broad spectrum fungicide. - Millet
I was also VERY surprised that it was greasy spot, i didnt think I'd have to deal with any of those "specialized" diseases growing them indoors, in Maine. However, i am 100% certain that it was indeed greasy spot. If i had a camera i'd post some pics...just havnt gotten around to that purchase yet :P One theory i had was that the disease was introduced through purchasing supermarket fruits, i do remember buying/eating an unusually large amount of citrus a little before the disease made it's self known. Could that be possible? I was hoping the tree would put out lots of new growth in the spring, i was just uncertain since I've never grown a citrus to maturity, and never had to deal with such a vigorous disease! i have learned a tremendous amount through trial and error on all of my trees (about 22 in all now) and i really appreciate all of the help provided by people on this forum, it's been the number one place for info!
Greasy Spot is a fungal disease that usually affects leaves, but occasionally fruit as well. In the case of fruit the disease is commonly called Greasy Spot Rind Blotch. The disease can attack all types of citrus, but is historically worse on grapefruit. You should be given some sort of plaque to hang on the wall near your tree, saying "Here Grows The Only Lemon Tree In The State Of Maine Cured Of Greasy Spot". You and your tree would be famous, perhaps even in the Maine Citrus Hall Of Fame. Take care. - Millet
