Lemon Disease

Any idea what the disease is on my lemon tree? The 15-gallon tree was planted three years ago and has never born fruit. Lots of blossoms, but no lemons. And, it is ready to profusely bloom again. Here is photo of a diseased leaf.

Do you have any more photos? Does it appear to be on the tips and edges mostly? How widespread is it - just a little, 1/2, the whole tree? How big is the tree? When did this start happening? Have you used anything on it?

ceejaytown

Thank you for your reply. Here and following are four additional photos in order of progression. One half of tree is affected. The tree is five feet tall (although I had previously cut some thoroughly diseased, two-foot shoots off top). This is the second year that I have noticed. No treatment has been given.

Midway

Curled

Sagging branches

Also, please view earlier post in "California Gardening" forum titled "No Fruit Citrus".

Thanks you for those photos. They really helped. This looks like citrus leaf miner. The newer foliage is affected. With my tree, I just pluck off the leaves as I see it showing up in order to control it. But you may have to try another tactic. Here's a web site to help you: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74137.html

The sagging branches are common. You can prune them to shape.

I'm trying to figure out why it hasn't borne fruit. I've had to pick mine off because it overbears. Are you using pesticides? Is it in full sun? Do you fertilize?

Thank you again.

I checked the two citrus trees out with my local agrilculture extension in Bakersfield, and the 18-year expert specifically on citrus trees (it is a big industry here) confirms what you concluded. Namely, that the lemon tree is infested with citrus leafminers. He recommended reading the same link as you furnished. He went on to say that the leafminers have nothing to do with the tree bearing no fruit, just as you suggested.

He suggested that I use a 15-15-15 fertilizer, one pound now and one pound a month from now. It had earlier been suggested to me that I may be overwatering. The expert suggested, instead, that I may be underwaterilng. He said the sagging branches are normal, just trilm them. No, I have not used any pesticides.

Regarding my orange tree. He said it does not have leaveminers, and it was just an old fungus. And, that fungus has nothing to do with some leaves turning yellow, again normal. He also said that the ants on the orange tree should be gotten rid of, simply because there will be fewer to invade your house. He suggested I spray on the gound (not on the tree) a pesticide for the ants.

I have ordered some neem oil, and will see if that is of help.

Just for reference here is a photo of the mold on the ORANGE tree.

Once more, thank you.

The stuff on that leaf looks like sooty mold which you will commonly find if the plant is/was infected by aphids or scale (they leave behind honeydew and the mold grows on the honeydew). The ants also like the honeydew which is why you will often see ants on a plant that has aphids/scale. If you're still seeing ants on your tree now I'd inspect it for aphids and scale.

As far as the pollination--are these trees indoors or outdoors when they're blooming? Lots of blooms but no fruit makes me suspect a pollination issue and if they're indoors you don't have any pollinators to help you out so hand pollination may be needed. If they're outdoors I would think the bees, etc would take care of it for you but obviously they haven't been so again you might try hand pollination and see if that helps.

ecrane3

The tress are outdoors with full sun 9-3. I will look into hand pollination.

Regarding the possiblity of aphids. I agree. See attached photo. It does look like a nest (with small, dirty-whitish webbing). I realize now I neglected to send this orange tree photo (it was in another set) to the agriculture extension. Is neem oil effectilve against aphids?

Thanks for steering me in the right direction.

Reddaddy

Aphids don't make webs like that, if you have aphids you will see them usually on the leaves, they're often green but also come in other colors. They're pretty easy to spot, they tend to hang out on the tender new growth and there are usually a fair number of them. Bad spider mite infestations can result in some webbing but I don't see any of the other symptoms of spider mites on your leaves (the telltale sign of spider mites is a stippled yellow pattern on the leaves). If you've got ants on your plants now I would check them for scale, it will usually look like dark bumps on the stems.

I agree with ecrane on the fungus issue. That is a sooty mold fungus, and that means a sucking insect is or has been snacking. It is not a fungus that penetrates into the plant. It lives on the sugary substance the sucking insects eliminate. Ants like it too. Look on the leaves for the critters also. There is also a black fly that likes citrus - check under the leaves. Very small, but in groups. I have had that on a few leaves, and cottony cushion scale, which is white and fluffy and big - very easy to see. All sucking insects...

No aphids. Some bumps on branches and leaves, not stems. Bumps on branches are squishy and spread like thick paint. Bumps on leaves are dry amd flake off. Neither is extensive. Nor is leaf damage widespread. No sign of movement. Here and following are these photos: Bumpsonbranch, Bumpsonleaf, Early, Advanced.

Reddaddy

Bumpsonleaf

Early

Advanced

The things on the stem do look like scale. Can't tell what the things on the leaves are but on some of my plants I'll find scale on the leaves as well as the stems that could be them too (maybe two different kinds if one is squishy and one is hard). Here is some info about scale from UC Davis: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7408.html

Just a follow-up: After two feedings of 16-16-16, here are the results for my lemon and orange:

Lemon: profuse blossoms and modest, healthy fruit development. No increase in disease.

Orange: decent blossoms and a half dozen starting fruits, all of which turned brown at pea size and fell off. The scale has greatly increased and now covers whole tree, branches and twigs only, no leaves affected.

Reddaddy

This message was edited Jun 3, 2009 7:22 PM

Have you made any attempts to control the scale? I would definitely work on that if I were you--if you get too bad of an infestation it puts a lot of stress on the plant since they suck juices out of it so your trees will be happier if you get rid of them.