The tips of my Meyer Lemon tree are turning brown. Is this a sunburn or deficiency? What do I need to do to fix this? Today I sprayed it with horticulture oil and put it in my shop out of the sun and will keep it there for four days. A little history on the tree is.. It's a 3 year old tree. (May 2009). I repotted it in CHC/peat April or May 2011 and it did go into shock but it's coming back around. (I think) I repotted it in a cement pot due to the light weight medium. It kept blowing over. Do you think the cement pot is a problem? I see new flush of leaves coming on but I have been getting alot of twig die back. Thanks ahead for any feedback. Pictures



.

I believe it is neither sunburn, nor deficiency, but rather a build up of soluble salts in the root zone to toxic levels. From the looks of the leaves, it mush have been quite some time since you have flushed out the container with clean clear water in the amount of 2 - 4 times the containers volume. Lastly, do you know the concentration in PPM of the dissolved salts in the water that you use to water your tree? - Millet

I do not know the PPM. I will need to learn how to find this out. We are on well water and have an iron filter only (no water softener) attached. If I flush the tree, and not fertilize for a while will that keep it alive? Or should I take it completely out of the container and change the medium? Should I put some Epsom salt water on it?

Thank you Millet. I just flushed out my tree for about an hour. Hope it's not too toxic to be saved. I will still need to find out the PPM of dissolved salts in my water.

Now that you have flushed your tree, you can again start to fertilize your tree with the next watering. I also use well water as my source of water. About six months ago I took a gallon of my well water to a testing lab and had it analysed for agricultural water. It told me everything that was in the water. Some elements were low, some were fine, some were high, and a couple were at toxic levels when applied over time. I now dilute my well water with rain water. The cost for the analysis was under $100 dollars. You should flush your tree's root system 3 or 4 times a year.

The damaged leaves will not improve, but all new growth should be a nice healthy green green. The best to you and your tree.. - Millet(185 BO-)

OK, will do that. Thank you so much.

What kind of fertilisers (foliar or water-soluble ) do you use? Is it contain urea (carbamide)?

Generally, there are two types of fertilizer. Water soluble and slow release. Container citrus can be fed with both, you can't go wrong with either one. Use of water soluble, tends to eliminate the possibility of burning the plants. Personally, I prefer water solubles, and I feed my plants with normal strength during its growing season which is here, usually from mid March to early October. Also, I do not use urea-based fertilizers, although they can be used in foliar applications.

Take care,
Igor

I asked the type of fertilisers because I think it's a biuret toxicity, but I'm not sure.

Oh sorry, I thought it was more like a general question for all the members here. Since the last post was quite some time ago, although you're probably right for the toxicity.

Sorry for the misconception.
Igor

Igor, yes it's an old thread, but I'd agree, that's classic biuret toxicity symptoms, so is a good photo record to see.
Malcolm

The fertilizer I use is Osmocote smart release 19-6-12 and the minors is Axilo Mix 5 and I looked on the bag and it doesn't say it contains urea nor carbomide. Millets suggestion of flushing the tree worked and all the new growth is nice and green. Here's a list of the Axilo Mix 5 that's listed on the bag.

Magnesium - 6%
Boron - 0.5%
Copper - 1.5%
Iron - 4.0
Manganese - 4.0%
Molybdenum - 0.1%
Zinc - 1.5%