Magnesium

Magnesium (Mg) is an essential for many plant functions, including photosynthesis, sugar synthesis, starch translocation, and plant oil formation.  It is at the core of the chlorophyll molecule, and an essential ingredient for healthy plants.  It also aids in seed germination and in the formation of fruits and seeds

role in growth

  • Absorbed by plants in the ionic form (Mg2+)
  • Classified as a “secondary mineral” because it is needed in relatively large quantities, but deficiency of this nutrient are less frequent when compared to N, P, and K (primary nutrients)
  • Dominant role is in the formation of chlorophyll, the molecule essential for photosynthesis
  • Necessary for the stabilization of nucleic acids, ribosome particles, and for assisting in the movement of saccharides throughout the plant
  • Deficiency symptoms are observed in older growth due to the fact that Mg is a mobile nutrient
  • Deficiency symptoms include leaf interveinal chlorosis, marginal yellowing, and marginal curling
  • Reduced availability under highly acidic conditions
  • Significant sources of this nutrient include dolomitic lime, magnetite, and organic matter

Magnesium (Mg), as an essential mineral element for plants and microbes, can have both indirect as well as direct effects on disease. A deficiency or excess of Mg can influence a wide range of physiologic functions because of these interrelated processes. There are fewer reports of direct effects of Mg deficiency or excess on plant disease than for many elements because of its participation in a wide spectrum of general physiological functions so that individual activities involved in defense, virulence, or pathogenesis are not as easily characterized. The ability of Mg to compliment or antagonize other minerals can result in different disease responses to Mg under varying environmental conditions. Fusarium wilt pathogens tend to be less severe when adequate Mg is available, and Mg increases resistance of tissues to degradation by some pectolytic enzymes of macerating or soft rotting pathogens. In contrast, high rates of Mg that interfere with Ca uptake may increase the incidence of diseases such as bacterial spot of tomato and pepper or peanut pod rot.  Management of Mg nutrition to reduce disease, in balance with other minerals, is an underutilized tool for disease control. (Huber & Jones, 2013)

Deficiency

Magnesium Deficiency. Photo by CHA

Magnesium Deficiency. Photo by CHA

Magnesium Deficiency. Photo by CHA

Magnesium Deficiency. Photo by CHA

Magnesium Deficiency. Photo by CHA

Magnesium Deficiency. Photo by CHA

Sources of Magnesium

Magnesium Sulfate

Magnesium Sulfate

Foliar feeding with Epsom Salts is the fastest way to correct a magnesium deficiency. We have seen good results foliar feeding 1 tablespoon/gallon.  The Epsom Salt Council has further information as well. Click on the icon for more information.

Selected References

The role of magnesium in plant disease. Don M. Huber and Jeff B. Jones. Plant and Soil Vol. 368, No. 1/2, Part I: Special Issue: Magnesium in Crop Production, Food Quality and Human Health (July 2013), pp. 73-85