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My mature lemon tree is having problems. It always produced LOTS of lemons. Since I trimmed off some dead branches a year and a half ago it produces only a handful. Also, and probably more important, bark on some of the branches is splitting and those branches are dead or dying. I have looked at a lot of web sites but haven't found anything that mirrors my situation.

The trunk appears fine. The upper branches (a lot of them) have split bark. The exposed wood looks healthy--no sap oozing. Lemon production is down drastically.

I am in Burbank, CA where we have very hot summers and, of course, there is the drought. About a year ago I began watering and fertilizing the tree. This hasn't had any noticeable effect. I've lived here 20 years and the tree was mature when I moved in. Don't know how old it is.

Any help you can provide would be greatly appreciated.

Thanks.enter image description here

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Bark splitting without oozing usually is from freezing or sunburn. When you cut back the deadwood it may have exposed areas to sun that weren't used to it. Did you have a hard freeze a few years ago? It maybe that's what started what your tree is going through. Fruit production after a hard freeze can be next to nothing. We had a hard freeze a few years ago, our lemon tree which normally has a 1000 or more lemons only had 12 the next year. Also older citrus trees tend to become alternate bearers. In the picture you posted it looks like there is new growth, that's a good sign.

  • Alternate bearing is usually the result of under pruning. Regular pruning after the fruit have ripened and been picked can help keep the interior healthy by providing spotted but consistent sunlight to the interior of the tree. This prevents the tree from getting sunburnt when a portion of it dies off from a freeze for instance. Pruning also tends to thicken branches which also protects a little better from freezing. – Escoce Dec 12 '17 at 19:28
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I don't know for sure, but I have some insights based on an experience with an apple tree we had.

The apple tree had received way too much wood ash, and also a bunch of diatomaceous earth. The trunk and branches were splitting in a dry fashion that might be the same fashion your tree is splitting. The leaves were yellow. The tree was probably in desperate need of nitrogen and more acidic soil, and well as some extra magnesium. Wood ash contains lots of calcium and potassium. It may raise the soil PH considerably and potentially hinder nitrogen and magnesium absorption (if used in large amounts).

We had a winter that killed a bunch of cherry trees nearby, I hear. This may also be somewhat responsible for this tree splitting, but our other four apple trees are fine. I suspect the wood ash and/or lack of nitrogen had something to do with it.

I would recommend getting a soil test for PH and nitrogen/potassium/magnesium levels. I suspect giving it more nitrogen and/or Epsom salt (magnesium sulfate) and/or lowering the soil PH may help out. This is just a hypothesis, though. You would need to run tests or experiment to be sure.

Nitrogen does actually help to increase the number of fruits on a plant, I've read, but it doesn't increase fruit size. I believe the benefits of nitrogen are much more pronounced in full sun. Our apple tree gets a lot of sun. Maybe that also contributed to the cracking, but I tend to think it's not the full problem.

If your magnesium levels are fine, but are just being blocked by too much potassium, I recommend not adding too much magnesium to compensate, since once the potassium gets used the extra magnesium might inhibit manganese uptake. I would just add a little extra in this case, and wait out the rest.

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