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Author Topic: Can I use epsom salt as a foliar spray to combat magnesium deficiency?  (Read 740 times)

Daintree

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I have some potted citrus that apparently have varying degrees of magnesium deficiency (according to the pattern of the chlorosis and age of leaves affected).
Can I foliar spray with epsom salt?  Or is there another foliar spray that would work better/faster? I want to green them up fast.
Or should I just treat the soil with epsom salt, or something else??  I have a dozen different types of citrus trees, all in pots.

Thanks!

Carolyn

Millet

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Re: Can I use epsom salt as a foliar spray to combat magnesium deficiency?
« Reply #1 on: November 14, 2016, 10:06:41 AM »
Yes magnesium sulfate can be  applied as a foliar spray.  However, you would be much better applying it as a soil solution.  As a soil solution apply 1 TBS/gallon dissolved in warm water to the root zone. Epsom Salts does not fully dessolve in cool water, therefore dissolve it in a WARM water solution, and when it cools down apply it. Depending on the gravity of the magnesium deficiency, it can take up to a year before the leaf sysmptoms go away. - Millet
« Last Edit: November 14, 2016, 12:29:33 PM by Millet »

Daintree

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Re: Can I use epsom salt as a foliar spray to combat magnesium deficiency?
« Reply #2 on: November 14, 2016, 10:42:42 AM »
Thanks!
Yeah, the fertilizer I have been using apparently doesn't have enough magnesium in it, so I am switching, but wanted to give my trees a head start.  Hopefully they will be looking better soon.  About half my trees are affected, and about half the leaves on each tree are showing signs.

Carolyn

jbclem

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Re: Can I use epsom salt as a foliar spray to combat magnesium deficiency?
« Reply #3 on: November 16, 2016, 07:39:55 AM »
I read in an older Willets & Newcomb newsletter(2007), that magnesium nitrate was the best way to correct magnesium deficiency in citrus.  " Magnesium sulfate has not
been found effective as a foliar spray.  Magnesium nitrate has been demonstrated to correct magnesium deficiency."  They also mentioned that in the acidic citrus soils of Florida, magnesium deficiencies had been successfully treated with magnesium sulfate (Epsom Salts).  And that "correcting magnesium deficiency in the soil can be slow in acid soils and very difficult in alkaline soils. Foliar sprays have had the best effect".
 Willets & Newcomb are a wholesale nursery here in California, one of the citrus suppliers for Costco.

I also have a 1969 paper from the Florida State Horticultural Society about correcting magnesium deficiencies in limes, in calcareous soils, using magnesium nitrate.  They wrote: "magnesium nitrate at 10 pounds per 100 gallons was  sprayed  on  spring-flush  leaves 2/3rds to 3/4 expanded.  Magnesium deficiency symptoms were practically eliminated in 4 to 6 months.  The use of  magnesium  sulfate  alone  as  a foliar  spray has produced little or no correction of magnesium deficiency in leaves(5)".  Also, for maximum absorption, magnesium nitrate residues should remain on leaf surfaces for 72 hours or longer before rain or irrigation."  I have this paper as a pdf file if anyone wants a copy.

It took me a while to find magnesium nitrate in small quantities at a reasonable price, found it at a hydroponics website.  It was called Magnisal.  I bought a pound of it and used it for a while, but ran out and haven't re-ordered.  I mostly used it mixed with a soluble fertilizer, only tried it once as a foliar spray...so I'm not sure if it's what worked but nine months later my container citrus leaves are looking pretty good, the yellow areas in older leaves mostly gone..   It's available if anyone wants to try it.  I ordered it from this place:
http://www.customhydronutrients.com/

As an aside, I also ordered S.T.E.M  (soluble trace element mix) from them.  And I've occasionally added it to my miracle-gro soluble fertilizer application.

Sorry to barge in, but I'd like to know what you think of this information Millet.
 

Millet

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Re: Can I use epsom salt as a foliar spray to combat magnesium deficiency?
« Reply #4 on: November 16, 2016, 04:50:28 PM »
jbclem, very good information, thanks for your post.  Common chemicals used for the correction of magnesium deficiencies: magnesium sulfate (Epsom Salts), magnesium nitrate, and magnesium oxide. As mentioned by jbclem the last two are more difficult to locate. - Millet

 

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