Calcium Nitrate Can Help Reduce Pink Rot

Pink Rot is a malady that is caused by the soil borne fungus Phytophthora erythroseptica which causes serious economic losses in potatoes. The fungus has become resistant to many fungicides and there is little varietal resistance to the disease, so alternative control measures are required.

Pink Rot Out of field Jeff Miller.jpg

Pin Rot in potato tuber. Photo by Jeff Miller, Miller Research.

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Pink Rot progression. Photo by Jeff Miller, Miller Research.

YaraLiva® Calcium Nitrate products as part of a comprehensive plan can help reduce losses due to Pink Rot in three ways:

  1. by helping to maintain soil pH,
  2. supplying nitrate nitrogen, and
  3. by supplying soluble calcium which strengthens cell walls and reduces the pathogenicity of the fungus.


Phytophthora erythroseptica is a fungus, and as such flourishes in low pH soils, whereas bacterium do better in near neutral pH soils. Fertilizers that supply ammoniacal nitrogen including ammonium sulfate (AMS), diammonium phosphate (DAP), monoammonium phosphate (MAP), urea-ammonium nitrate (UAN), and urea tend to acidify the soil making the environment conducive to P. erythroseptica. The nitrate nitrogen supplied by YaraLiva calcium nitrate does not lower nor raise the soil pH. Nitrate N is also the preferred nitrogen source for potatoes in a ratio of 80% nitrate:20% ammoniacal nitrogen.

Nitrate N

Fungi prefer both low pH and ammoniacal N. Ammoniacal N is rapidly metabolized to amino acids which become a food supply for the fungi. Nitrate N is not a preferred food source for fungi and it does not encourage fungal proliferation. Additionally, it is already in the form that is readily taken up by the potato crop.

Reducing Pathogenicity

Phytophthora erythroseptica generally infects potatoes through stolons or underground stems, then migrates to the tubers. Healthy tubers can also become infected through wounds, enlarged lenticels, and through tuber eyes when they come into contact with infected tubers during harvest, storage and other handling processes. A supply of soluble calcium during the growing season-especially early-has been shown to significantly reduce Pink Rot infection[1]. This is mainly accomplished two ways. First, calcium is important for superior cell wall and plasma membrane strength. Strong cell walls help deter pathogenic infection and also limits cellular leakage during stress. Second, fungi use an enzyme, polygalacturonase, to break down cell walls which allows the pathogen then to feed and further infect the tuber. Soluble calcium interferes with the activity of this enzyme, which helps maintain good cell structure and good tuber integrity.

Take it Home

Infection occurs when the disease triangle-susceptible host, favorable environment and pathogen-is optimized. The pathogen responsible for Pink Rot, Phytophthora erythroseptica is widespread in potato producing areas. YaraLiva Calcium Nitrate can help mitigate the other two sides of the disease triangle by helping to limit pH reduction and by supplying nitrate N which is not a preferred source for the fungi, and by making the potato host less susceptible by creating stronger cell walls and denaturing the enzyme that breaks down the cells. These two functions can help mitigate the occurrence of Pink Rot in potatoes.


YaraLiva Calcium Nitrate is available in dry and liquid forms.


  • 15.5% Nitrogen - 14.5% Nitrate N, 1% Ammoniacal N
  • 19% Calcium

YaraLiva® CN-9®

  • 9% Nitrogen - 8.42% Nitrate N, 0.58% Ammoniacal N
  • 11% Calcium

Contact your local Yara representative for more information on YaraLiva Products.

[1] Benson, Jared H., “Effect of Ca and pH on Disease Severity of Pink Rot Phytophthora erythroseptica in Russett Norkotah Potato Solanum Tuberosum” (2008), Brigham Young University.

Learn more about Calcium Nitrate for potatoes.


jimmy ridgway
Jimmy Ridgway
Regional Sales Manager

Idaho / Intermountain West