Foliar Symptoms of Corn Nutrient Deficiencies
Corn foliar nutrient deficiencies in corn can be the result of:
- Actual deficiencies
- Plant interactions with the environment
- Herbicide injury
- Insect injury
Foliar and soil testing can help determine if there is a plant or soil nutrient deficiency. Plant deficiencies in the spring often disappear when soils become warmer.1
Foliar symptoms: When doing field scouting, yellow, brown, purplish, striped, or desiccated corn leaves may be found. These symptoms can be indications of nutrient deficiencies.
- Sulfur: youngest leaves show yellow striping particularly at the leaf margin because sulfur is not easily translocated within the plant (Figure 1A).
- Magnesium: plants initially are pale because there is a shortage of chlorophyll. Severe deficiencies can cause leaves to develop full-length striping with green veins and yellow tissue between the veins. Develops on lower leaves first (Figure 1B).
- Nitrogen: oldest leaves turn pale or yellowish-green and develop an inverted “V” or spear-shaped discoloration starting at the leaf tip and extending toward the base of the leaf (Figure 1C).
- Phosphorous: leaves on young plants appear to be purplish (Figure 1D).
- Zinc: interveinal chlorosis on upper leaves can occur with veins, midrib, and leaf edges remaining green. Stripes develop on either side of the midrib and leaves may turn nearly white if the deficiency becomes more intense. Stunted plants may have internodes shorted (Figure 1E).
- Potassium: leaf margins may become yellow and brown (Figure 1F).
Nutrient deficiencies may exist when there is a reduction in uptake. The cause of the deficiency may be caused by:
- Compaction (Figure 2, left)
- Injured roots from insects, diseases, fertilizer burn, or chemicals (Figure 2, right)
- Reduction in plant metabolism and photosynthesis from cool nights, cloudy weather, and/or water-saturated soils
- Warm temperatures after a cool period can cause plants to grow rapidly and may induce temporary deficiencies
- Slow nutrient release from plant residue
- Soil attributes can cause deficiencies - low soil organic matter (S), low pH soils, high pH soils (Z).
Nutrient deficiencies affect potential yield and the earlier the deficiency is corrected by favorable environmental conditions and/or the application of additional nutrients can help reduce the potential for yield reduction. Deficiencies that are season long can result in substantial yield loss. If roots are injured by insects or chemicals, and depending on the severity of the damage and the time required for new root growth, the potential for yield loss increases. For example, sulfur deficiencies lasting longer than 21 days after emergence can result in a yield loss of 1 to 2 bu/acre.2
Management of nutrient deficiencies by utilizing soil and crop tissue testing to determine if there is a soil nutrient or restricted plant uptake, or there is reduced metabolism. When plants with a suspected nutrient deficiency are sampled, a sample of unaffected plants should also be collected and analyzed to help determine if a nutrient deficiency is the cause. Tissue samples taken during the growing season can determine if a supplemental fertilizer application should be made.3 Tissue analysis procedures vary by lab; however, in general, the corn ear leaf at silking should be sampled for sulfur, magnesium, and zinc levels.4 An early-season tissue analysis can be done after the seedling stage of growth, but prior to tasseling.
A tissue test, in combination with a soil test, may provide answers as to why plant levels are high or low. Soil test results can be the most useful for predicting nutrient needs for the next growing season, but may not give reliable results for sulfur levels. Corn responds best when soil pH levels range between 5.6 to 7.5. A pH goal for continuous corn or a corn-soybean rotation should be around 6.0 on acid soils. If alfalfa or cover crops are in the rotation, the pH level should be 6.5 to 7.0. Appropriate amounts of lime can increase soil pH and help increase the availability of plant nutrients.
Nutrient deficiencies often dissipate when soils become warmer and drier because root growth, microbial activity and the breakdown of organic material, and the release of nutrients are enhanced. When root growth is unrestricted roots can reach water-soluble nutrients such as sulfur and nitrogen that may have moved deeper into the soil profile. Between growth stages V3 to V5, while corn plants transition from seed dependency to acquiring energy form photosynthesis, plant appearance can be variable and can be caused by environmental conditions. During early growth stages, observations of nutrient deficiency symptoms should be documented and tissue samples gathered at silking if the symptoms persist. Correcting the deficiency may not be feasible for the current crop; however, soil preparation for next season can include fertilizer applications based on soil test recommendation and alleviation of compaction.
1Fernandez, F. 2009. Identifying nutrient deficiencies in corn. the Bulletin. No. 13. Article 6. University of Illinois. http://bulletin.ipm.illinois.edu/.
2Heiniger, R., Crozier, C., Hardy, D., Walls, B., and Reich, R. 2018. Sulfur deficiency symptoms in emerging corn. North Carolina State University. http://corn.ces.ncsu.edu.
3Stevens, G., Motavalli, P., Scharf, P., Nathan, M., and Dunn, D. 2002. Integrated pest management: Crop nutrient deficiencies and toxicities. IPM1016. University of Missouri-Columbia.
4Thom, W.O., Brown, J.R., and Plank, C.O. 2000. Sampling for corn plant tissue analysis. NCH-15. National Corn Handbook. Iowa State University Extension.
Hartzler, B. and Anderson, M. 2018. Fomesafen carryover to corn. Integrated Crop Management News. Iowa State University Extension and Outreach. https://crops.extension.iastate.edu/. Kaiser, D.E. and Vetsch, J.A. Sulfur for Minnesota soils. University of Minnesota Extension. https://extension.umn.edu/. Kaiser, D.E. and Rosen, C. 2016. Magnesium for crop production. University of Minnesota Extension. https://extension.umn.edu/. Sutradhar, A.K., Kaiser, D.E., and Rosen, C.J. 2016. Zinc for crop production. University of Minnesota Extension. https://extension.umn.edu/. Web sources verified 011519. 130411060201