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Author Topic: Boron Toxicity or Magnesium Deficiency?  (Read 483 times)

Kelley_GA8a

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Boron Toxicity or Magnesium Deficiency?
« on: June 13, 2019, 05:50:59 AM »
Apologies for the noob question, but do the below leaves reflect boron toxicity or a magnesium deficiency? My trees are fertilized with Osmocote Plus, while alternating FoliagePro and Fish Emulsion. Towards the end of last summer, I stopped using FoliagePro and was only using FE. Now, Iím afraid Iíve experienced a nutrient lock out. Weíve had about 5 straight days of excessive rain, so theyíve gotten a good flush.

Note: my young grafted trees are still indoors, using the same water source (but were not fed FE) are all dark green.









2nd Note: the third picture shows new growth on a tree that almost exclusively produces dark red shoots that purple out before turning green. This new growth has been entirely green from the start.

Thanks for your time and any/all advice is greatly appreciated 🙂
« Last Edit: June 13, 2019, 06:24:49 AM by Kelley_GA8a »

Laaz

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #1 on: June 13, 2019, 06:26:51 AM »
Looks like magnesium deficiency. I think you are way over doing it with sprays & fertilizers... The salts that build up in the soil can really wreak havoc on your container trees. My theory is always less is better. I would pull them out of the pots, wash the soil off thoroughly & replace the soil.

Kelley_GA8a

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #2 on: June 13, 2019, 06:32:22 AM »
Thanks Laaz! Iíve actually only fertilized twice this year. What is your feeding schedule?

Laaz

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #3 on: June 13, 2019, 06:49:15 AM »
I fertilize once in late winter, once in mid spring & again in early July. Remember between feedings, when you water container citrus you want to really water it well to flush out any salts that have built up in the soil. This is why you want a really good draining soil, as you don't want the roots sitting in sludge at the bottom of the container. "Potting mix" is notorious for turning into muck... The Miracle gro garden soil is already packed with fertilizer & won't need any more fertilizing for at lease 6 months. Mixing Turface MVP in really improves the drainage...

When you water, you want to water until you see a decent amount of water flowing out the holes in the bottom of the container. Just wetting the soil will cause any salts to slowly drop down to the root zone & concentrate there.

Kelley_GA8a

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #4 on: June 13, 2019, 07:01:41 AM »
Thanks Laaz, my mix consists of soil conditioner and perlite only. I always water thoroughly as well. Iíve decided to stop using FE and only use Osmocote and FP moving forward. I only apply Osmocote once in winter, and FP is only during the growing season.

Laaz

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #5 on: June 13, 2019, 07:13:29 AM »
What is FP?

Kelley_GA8a

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #6 on: June 13, 2019, 07:25:25 AM »
FoliagePro

Laaz

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #7 on: June 13, 2019, 07:32:07 AM »
I have never sprayed my plants with a foliage spray & never had a issue.

Kelley_GA8a

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #8 on: June 13, 2019, 08:41:58 AM »
Iíve never sprayed mine either - itís used when watering (not every watering; Iíve only used it once this year).

brian

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #9 on: June 13, 2019, 09:17:54 AM »
I only ever use Osmocote Plus now and I've never seen on my own trees the damage pattern you have here, Kelley.  I'm not familiar with FoliagePro.
« Last Edit: June 13, 2019, 09:19:36 AM by brian »

Millet

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #10 on: June 13, 2019, 10:45:40 AM »
Laaz is certainly correct, the deficiency that Kelly's tree has is most definitely magnesium.  It can be corrected by dissolving 2- 3 oz. of Epsom Salts (MgSO4) in a gallon of WARM water and apply as a foliar spray. .  Do not apply at high temperatures or low humidly.  Apply in the morning or late afternoon,  Can also be applied to the soil's root zone.. 

JoeReal

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #11 on: June 13, 2019, 03:14:47 PM »
When I apply any fertilizer containing N, I make sure that the Mg is 1/4 of that, in terms of elemental weight.

JoeReal

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #12 on: June 13, 2019, 03:16:53 PM »
Also notice that if you keep your trees outside in a subtropical climate like California, some citrus cultivars such as those in the Fortunella group and their hybrids, and most lemons will show a lot of fake deficiency symptoms during the winter and then they magically disappear as the weather warms up in spring. These kinds of temperature related "fake" deficiencies are seldom ever discussed in many Citrus Textbooks and I have observed it throughout our lives here in California.

From an ecological point of view, the lemons and kumquats and their hybrids that shows yellowing during the chilly temperatures are actually natural adaptations that help minimize chilling injury during full sunlight in the cold mornings of winter.


« Last Edit: June 13, 2019, 03:33:57 PM by JoeReal »

Kelley_GA8a

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #13 on: June 13, 2019, 09:36:57 PM »
Thanks for all of the advice, everyone! Millet, do you recommend foliar or root feeding of Epsom salts?

Joe, I am zone 8a, but my trees stayed outside most of the winter, only going inside our unheated garage a handful of times when the temps dropped. The funny thing is, my eureka and Genoa lemons are all dark green, but my Bearss Lemon and Santa Teresa lemons are suffering. I will apply the Epsom salt mix tomorrow and see how it goes. Iím thinking of sending my soil off for testing, too. Just to be safe and on the lookout for future issues.

Millet

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Re: Boron Toxicity or Magnesium Deficiency?
« Reply #14 on: June 13, 2019, 10:37:45 PM »
Kelly, you can apply the MgSO4 by either soil or foliar spray.  A foliar spray will work faster, but either method should correct the deficiency.  Note although the deficiency becomes corrected, the leaf symptom can remain.

 

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