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Dwarf Meyer Lemon - HELP! Rust mites?

Posted by liz-usa MA (My Page) on
Tue, Nov 13, 12 at 15:35


This is my first post.

A month ago, I bought a dwarf meyer lemon tree from a local nursery. I live in Massachusetts, in a tiny apartment with not outdoor space, so the plant must be an indoor one. I put it in my southeast-facing window, with a grow-light six inches above it. When I first bought it, the tree looked more like a bush, growing in crazy directions and lopsided. I pruned it to look more like a bush and planted it at an angle to appear more symmetrical.

Over the last month, the tree has continuously shed leaves. At first I thought it was due to transplant shock. I switched to watering twice a week when I discovered the roots might need to "take hold" first, then switched back to once a week because I was afraid of overwatering it. I recently put a wood stake in the soil to monitor moisture levels more accurately from now on.

I am becoming increasingly suspicious that the tree is suffering from rust mites, and that this is causing defoliage. There was a lemon already on the tree when I bought it, and I didn't until a few weeks in that it was covered in sharkskin. I attempted to remove the sharkskin, and within the last week it came back with a vengeance. Some leaves, both old and new, become yellow with green spots on top. Wherever there is a green spot on top, there are black spots underneath, which I think is where the mites are feeding. These yellow-with-green-spot leaves are especially prone to falling off. But, some perfectly green, healthy looking leaves also occasionally fall off.

Much to my horror, as I tried to take pictures of my unripe, sharkskin lemon, it fell clean off. I have two dime-sized lemons developing on the tree. I also have many teeny tiny baby lemons developing all over the tree. Instead of growing its leaves back, the tree has poured its energy into flowering, which was really really nice. Now, there are an abundance of fertilized flowers, but several of my branches have been stripped bear. Is there any way to get the leaves to grow back?

Here are the pictures of the plant. Please help me to diagnose it. Do the leaves look like they are suffering from citrus rust mites?


I've been spraying down the plant with water every few days. As a natural remedy for rust mites, I have even been wiping the leaves and branches and fruit down with rubbing alcohol every few days. At times, this seemed to delay the yellowing of the leaves, but my constant contact with the tree has also accidentally knocked off several leaves.

Right now my first concern is the fact that the tree is not replacing the leaves it is losing. Please help!

Follow-Up Postings:

RE: Dwarf Meyer Lemon - HELP! Rust mites?

perhaps the link will help.

3rd, 4th and 5th pics shows yellow vein chlorosis, low nitrogen. have you been fertilizing?

Here is a link that might be useful: 2012 Florida Citrus Pest Management Guide: Rust Mites, Spider Mites, and Other Phytophagous Mites

RE: Dwarf Meyer Lemon - HELP! Rust mites?

The soil I planted the tree in had fertilizer (Miracle-Gro Cactus, Palm and Citrus Soil), and on Sunday I fertilized with Miracle-Gro (12-4-8). The fertilized soil made me think that it wasn't a nutrient problem.

What's strange to me is the combination of yellowing and green spots. None of the information on rust mites that I've seen mention that problem. What do you think the green spots could be a symptom of?

I'd like to confirm what the problem is before I spray it down with insecticide, especially since this is an indoor plant near my couch. I've tried looking with a magnifying glass, to no avail. I don't have a microscope.

RE: Dwarf Meyer Lemon - HELP! Rust mites?

Liz, fertilized soil will not be enough for citrus. A couple of things - first off, I suspect your potting medium is too wet and soggy. I know you've repotted, but none of the container folks here like MiracleGro soil, it just compacts and doesn't breath well enough for citrus roots. If you search for "511" mix in this forum, you'll get a great container potting mix. MeyerMike can help you out with that for sure, his citrus do exceptionally well with 511 mix. Secondly, and due to that, I am suspecting you have something fungal going on. When you see round spots like that, it is almost always something fungal in nature. You don't need a microscope to see mites. I can see them with my 57 yo "mature" eyes :-) Mites give a very classic appearance to leaves, they look speckled or stippled. Your leaves are not displaying that at all. Black spots under the leaves sounds like Greasy Spot to me. You'll need to treat with an anti-fungal agent. Also, a tree that pours its energy into blooming, while failing is a tree that is in trouble. It feels that it is dying, so this is its last ditch effort to reproduce itself. More sunlight, better potting soil, switch to a better fertilizer with micronutrients like Foliage Pro by DynaGro may all help. The fruit that fell off looks like wind damage scarring. I would pull off all the other little fruit right now, and let's see if we can get your little tree to put its energies back into its canopy, instead of the fruit.

Patty S.

Here is a link that might be useful: University of Florida: Citrus Greasy Spot

RE: Dwarf Meyer Lemon - HELP! Rust mites?

OK, I'm planning to go to Home Depot to grab my supplies. Just checking that I need:
5 parts pine bark (Earthgro Red Mulch)
1 part Perlite
1 part Sphagnum Peat Moss
1 bottle Southern Ag Liquid Copper Fungicide

Does this sound right?

RE: Dwarf Meyer Lemon - HELP! Rust mites?

Also, the only way I can upgrade the tree to a 5-gallon pot would be to put it in a rectangular planter. Would this be ok? Or, does it has to be a round 5-gallon pot?

RE: Dwarf Meyer Lemon - HELP! Rust mites?

Just replanted in 5-1-1. Used Orchid Bark (just bark, no perlite), because the pine bark at Home Depot was removed to make way for Christmas trees.

Will spray with Copper Fungicide tomorrow, when I can take it outside.

RE: Dwarf Meyer Lemon - HELP! Rust mites?

Liz-USA would be interested to hear how you went. I've a pomelo (citrus maxima) exhibiting the exact same symptoms photographed in your top photos. From what I can gather Australia doesnt get grease spot... yet...these leaves are looking very similar. My pomelo went straight into 511 and has seemed happy in it, although now it is looking less happy. Would be keen to know what, if any treamtent worked on your meyer lemon tree...

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