Zinc and manganese: Be on the alert for deficiencies in sensitive crops

Certain crops including corn, dry edible beans, oats, potatoes and several other vegetables have a high response to Zn and Mn fertilizers when soil levels are too low.

Zinc (Zn) and Manganese (Mn) are two essential micronutrients for plant growth. When growing crops known to be sensitive to zinc or manganese deficiency, producers should be aware of deficiency symptoms. Zinc deficiency will result in off-color fields of corn, dry beans and other crops. Dry beans will become light green and, when deficiency is severe, the area between leaf veins will become light green and yellow near the leaf tips and outer edges. Corn lacking adequate zinc will display yellow striping of leaves. Manganese deficiency also results in yellow or olive-green foliage, reduced leaf size in potatoes and is generally similar to zinc deficiency.

Both Zn and Mn deficiencies can be corrected by applying an appropriate starter fertilizer near the seed at planting or by foliar application when deficiency symptoms are present.

Soils with pH of 7.0 or higher are more vulnerable to Zn and Mn deficiency.

Soil testing can determine if Zn or Mn are needed. When submitting a sample to the MSU Soil and Plant Nutrient Laboratory, indicate that you want the Zn or Mn test. The Zn and Mn tests are an additional $4 each, unless you purchase the pre-paid Zn-Mn sticker for $7 (minimum of 10), which gets both tests and saves $1 per sticker. Other reputable soil testing labs will also have the option for Zn and Mn testing.

Plant tissue analysis can also determine whether plants have sufficient Zn and Mn available. A complete plant tissue analysis through the MSU Soil and Plant Nutrient Laboratory costs $24 for field and vegetable crops ($27 for fruit crops) and includes N, P, K, Ca, Mg, Zn, Mn, Cu, Fe, B, S, Na, and Al.

Crops with high response to zinc fertilizer:

  • Corn
  • Dry edible beans
  • Onions
  • Snap beans
  • Sorghum
  • Spinach
  • Sweet corn

Crops with high response to manganese fertilizer:

  • Cucumbers
  • Dry edible beans
  • Lettuce
  • Oats
  • Onions
  • Peas
  • Potatoes
  • Radishes
  • Snap bean
  • Sorghum
  • Soybeans
  • Spinach
  • Sudangrass
  • Sugarbeets
  • Sweet corn
  • Table beets
  • Wheat

For more details and photos on Zn, Mn and other secondary and micronutrients, look over the MSU Publication “Secondary and Micronutrients for Vegetables and Field Crops.” Another online article of interest from Michigan State University Extension is “Micronutrient decisions for field crops.”

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