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Author Topic: splotchy yellow on leaves  (Read 123 times)

brian

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splotchy yellow on leaves
« on: June 23, 2020, 10:43:53 PM »
My valentine pummelo is showing this leaf pattern I have never seen before.  In addition, the leaves are much yellower than my other trees, despite receiving mostly equal fertilizer.  This is planted in the ground in my greenhouse.  Any idea what this might be caused by?  Not all leaves show this pattern, maybe 2/3 do.  I can't tell if these are the older leaves or the newer leaves.  The unaffected leaves are have no spots and are darker green (normal looking)



SeaWalnut

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Re: splotchy yellow on leaves
« Reply #1 on: June 24, 2020, 03:36:35 AM »
Looks like molybdenum defficiency.Not acid soil enough?

brian

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Re: splotchy yellow on leaves
« Reply #2 on: June 24, 2020, 09:28:13 AM »
Thanks.  I agree it does look like the description of molybdenum deficiency.  I don’t believe my greenhouse soil is acid, though, more likely it is alkaline.  Regardless, I am going to look into a micronutrient spray


“Molybdenum (Mo)
In Florida, Mo deficiency in citrus is commonly called “yellow spot.” The deficiency occurs when trees are unable to take up sufficient Mo from an acidic soil. Deficiency symptoms appear on the leaves as large interveinal chlorotic spots in early summer. As the leaves age, the yellow spots develop deposits of brown gum on the lower leaf surfaces, which may eventually turn black. In many cases, an infection of anthracnose causes the areas covered by the spots to die and drop out, leaving small holes in the leaves. When the deficiency is severe, the necrotic yellow spots enlarge and extend to the margins. Affected leaves eventually drop, and trees become almost defoliated during the winter.

Symptoms are seldom observed on fruit except when the deficiency is severe. Under this condition, large irregular brown spots surrounded with yellow discoloration may develop on the fruit. The discoloration goes only into the peel and does not affect the albedo. Symptoms of Mo deficiency appear more commonly on the sunny side of the trees.

Molybdenum deficiency usually occurs in acidic soils. The most common cure is to lime the soil to pH 6.0 – 6.5, after which Mo deficiency often disappears. It is easy to correct Mo deficiency with a sodium molybdate or ammonium molybdate foliar spray. If the spray is applied between summer and early fall, the leaves will re-green and the yellow spots will disappear from the upper surface. Most of the gum will also disappear from the lower surfaces of the leaves. However, black spots consisting primarily of cork cells will remain. One spray is usually sufficient for 3 years or more.”

I am mainly fertilizing with osmocote plus, which contains molybdenum, and occasionally foliar spray with Jacks HPF which does also.
« Last Edit: June 24, 2020, 10:23:59 AM by brian »

 

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