Please tell us a little more about the tree. When did this start? What are its growing conditions? How often is it watered? Has it been fed lately? What is it fertilized with? Commercial or organic fertilizer? Has anything changed? What is the tree planted in? Where in the house is it located? How much sun does it get daily? or is it grown with lights?

There are many reasons for your tree to be showing this condition. With the answers to the above questions we can possibly narrow down the causes.
Andi

I have the plant near a south-facing window in a mix of peat,vermiculite and some compost. It was fed with organic tomato food (4-6-8) when the flowers appeared. I water it only when the top layer of soil feels dry. Most of the little lemons (around 1 cm) have fallen off. I have a key lime in the exact same conditions which was bought at the same time (last Fall) which is healthy and holding its fruit.

Thanks,
Lakshmi

Peat and compost may make the soil hold water. Use a moisture meter or a stick/rod of some kind to make sure the lower parts of the pot are not soaking wet. Sometimes the top layer will feel dry but the middle and lower parts will be mush due to the PWT(perched water table).

Tomato fertilizer is not the best for citrus. You can use azalea/rhododendron fertilizer which is available at most garden centers and discount stores. This is close to the 5/1/3 ratio that citrus needs.

The fertilizer should contain micro elements if their not in the compost. This would depend on what the compost was comprised of and if it had leached out.

The yellow spots in the leaves could be due to over watering if the PWT is too high or the roots have grown into it. This is the main reason for well draining soil when growing in containers.

The problem doesn't look like a lack of iron either. However a lack of the micro elements will show the symptoms you are seeing.

If the soil is too heavy you can add perlite or very coarse builders sand. The sand will make the pot much heavier.

Can you post a picture of the entire tree, pot soil and all? This way we can see the whole thing.

Also if the leaves are dropping and leaving the petiole(the little wing below the main leaf) behind, its a sign of stress. Meyers lemons are cantankerous even at the best of times. The more you neglect them the better they thrive.

If you find that the roots are in the PWT you will need to allow the tree to dry further before watering. You can also place a wick in one of the drain holes to help drain the excess water out of the pot. Just stick a nylon rope in the drain hole and allow it to hang into a saucer. Do not allow the wick o contact the water in the saucer or it will wick back up instead of down. You can pour 3% hydrogen peroxide through the pot to kill off the bacteria that causes root rot and to place much needed oxygen around the roots. This is the store brand 2/$1 type of hydrogen peroxide from the dollar store.

The person at the nursery told me I should use tomato fertilizer at the time of flowering/fruiting when I went to buy azalea/rhodo fertilizer. He said that a/r fert or Miracid should be used if the plant showed signs that the soil was not acid enough.

The leaves are dropping and leaving the petiole. I will try the hydrogen peroxide but do I just pour it in undiluted? I worry that it might harm the plant.

Most of the plant still looks fine since the problem started only 7-10 days ago. I will take a picture during the day and post it.

Thanks for all the info.

Lakshmi

The 3% hydrogen peroxide will not hurt the plant and is poured straight from the bottle onto the root system, however if the plant is suffering from salt toxicity as I suspect it will not help unless you change the soil its presently growing in. The hydrogen peroxide will kill the bacteria that causes root rot from over watering. You can place a small fan near the pots to help the soil dry a bit better.

The tomato fert does not contain the micros that all citrus need. IF you are unable to find any fert containing micros, email me your address and I will send you some S.T.E.M. This stands for soluble trace element mixture. You only use 1/4 tsp in a gallon of water, once or twice a year. Its important to know that S.T.E.M. is not a fertilizer and should not be used as such as large amounts are toxic to the plant. Think of S.T.E.M. as a vitamin supplement one would take if they did not get it through the foods they ate.
Andi

Please disregard the the mention of salt burn as I confused your post with another. This is what happens when one is suffering from a severe lack of caffine in the morning. I really must keep things straight since there is no edit button in this forum.
Andi

Hi Andi - Thank you for your generous offer but I live in Canada :-) Do Miracid or Azalea/Rhodo fert contain micros? Or could you give me a brand name that does so I can search for it?

Here are some more pictures of my plant. Most of it still looks decently healthy but 95% of the fruit has fallen off and the leaves are slowly starting to turn color and fall off. I presume this can't be caused by scale- I had a problem a few months ago and only managed to get rid of it last month (I hope) using insecticidal soap.

Lakshmi

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Fallen fruit

If I have a tree that looks like that I will be extremely satisfied.
What is one leaf yellowing compared to hundred that are so green.
I just think that the soil needs some water.
I think the best policy is semi neglect your citrus. That's what I'd do.

This doesn't explain why 95% of my fruit has already fallen off. The veins of the leaves are starting to turn yellow.

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Lakshmi

I am not an expert on diagnosing leaves problem but in my opinion those leaves are the start of showing of lack of magnesium, one of the micronutirents missing in your fertilizer. In advance state the yellowing will look like yellowing of leaves in an inverted V position.
Regarding the dropping of fruits, it is normal for the tree to drop 98% of its fruit and only 2% or less retain by the plant.
You are better of to stick with the rodo, camelia fertilzer by Miracle Grow because that fert has micronutrients in them. A lot of people are happy with the fert in question.

After reading and rereading and looking at the leaves with magnesium deficiency I don't think I gave you the right prognosis.
I can't seem to find similar symtoms from all the pictures I have.
Sorry.

I noticed that there is also some brown spotting on the back. In the sunlight I see light green patches when looking through almost all the leaves. Most of the tips are starting to turn yellow...could this be due to overfertilization?

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Thanks,
Lakshmi

That looks an awful lot like the leaves did on my tree. I'm down to just two leaves now, but I blame most of that on a total lack of sun during the winter. I just has a CFL on it and kept it watered. Now that spring is finally returning I put the tree outside and I'm hoping it will send out a new flush of leaves for the season.

I also noticed that the roots in the first few inches of the pot were loose or already diconnected. They were a whitish color and I could see that they had a softer, whiter little strand inside when I pulled a piece in half. I'm assuming those were otherwise healthy roots since they were not dark or black, but I'll mention it here in case I'm wrong. The branches are green and sturdy without much brown-tip dieback.

For the original poster, don't let my tree freak you out. I don't have good windows to offer my tree when I bring it inside for the winter. Last year it dropped around 80-90% of its leaves over winter but came back with plenty of growth in the spring. I'm hopefully that it will be the same result this year.