UF/IFAS has put together information about the symptoms, causes, and solutions for magnesium deficiency in citrus.
“Magnesium (Mg) deficiency is a problem in Florida citrus,” shared a UF/IFAS blog article. The article then shared information on the symptoms, causes, and solutions for magnesium deficiency in citrus. See the details below.
Symptoms of Magnesium Deficiency
The article shared that “Trees with inadequate Mg supply have no symptoms in the new spring flush, but leaf symptoms will develop as the leaves age and the fruit expand and mature in the summer and fall. Leaves that have lost most of their green color due to Mg deficiency drop freely under unfavorable conditions.
Defoliated twigs become weak and usually die by the following spring. Severe defoliation will reduce the average size of individual fruit and cause a general decline in fruit production.”
Causes
The article explained that “In Florida, Mg deficiency in citrus is caused primarily by low levels of Mg on acidic, light sandy soils and on calcareous soils. Leaching of added Mg is particularly serious and substantially rapid when the soil pH is 4.5 to 5.0. Under such conditions, the use of dolomite to bring the pH to 6.5 will furnish Mg at the same time.”
Solutions for Magnesium Deficiency in Citrus
The article advised that “Soil application of Mg sulfate or oxide to provide 50 to 60 pounds of Mg per acre can be successful in correcting Mg deficiency when the soil pH is adjusted.
Under calcareous soils, the amounts of Mg applied must be greater than those applied on soils low in calcium or potassium.
Foliar spray applications of Mg nitrate (3 to 5 gallons per acre) can be very effective when applied on the spring and summer flush leaves when they are about fully expanded. Magnesium should be applied regularly at 20% of the nitrogen (N) rate unless leaf analysis shows more than 0.5% Mg.
If leaf Mg deficiency symptoms occur, Mg should be applied in the fertilizer. The rate should be increased up to 30% of the N rate until symptoms are no longer present in mature leaves of subsequent flushes.
If both potassium (K) and Mg status are low, sulfate of potash-magnesia, which contains both K and Mg in the sulfate form, is a very good option.”
See our next blog in the series on dealing with magnesium deficiencies in calcareous soils.
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