Scouting for Nutrient Deficiency Symptoms in Wheat
January 15, 2025
- Wheat should be scouted weekly to observe for nutrient deficiencies along with disease and insect concerns.
- Depending on nutrient deficiency, in-season foliar or soil applied applications may be available to help resolve the observed deficiency.
- Knowledge of deficiency symptoms and where they appear on the plant can help identify the deficiency.
Winter or spring wheat both require adequate nutrients to help maximize yield potential. Based on the crop, fertilizer applications are generally split (fall and spring) for winter wheat and applied at one time (before or at planting) for spring wheat.1 Fertilizer applications should be based on routine soil sampling to determine soil nutrient levels, pH, and cation exchange capacity. During the growing season, the crop should be scouted at least weekly for pest infestations, disease infestations, and nutrient deficiencies. If nutrient deficiencies are evident, tissue sampling and analysis can be helpful to verify the deficiency and help determine if a foliar or dry fertilizer application is warranted. In season applications may be applied via aerial, irrigation, or land equipment. To receive the best potential recommendations, growers should obtain and follow laboratory instructions for collecting, handling, and shipping plant tissue samples. Depending on the deficiency and growing conditions, yield potential may have already been negatively impacted by the time symptoms are noticeable.
Knowledge of nutrient deficiency symptoms can be helpful in diagnosing deficiencies and ruling out diseases with similar symptoms. Symptoms of deficiencies of nutrient that are mobile within the plant—nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg)—appear on older or lower leaves first and migrate to newer tissues if the deficiency continues.2 Symptoms of immobile nutrient deficiencies—manganese (Mn), sulfur (S), copper (Cu), iron (Fe), calcium (Ca), and boron (B)—appear on new growth and do not migrate to older tissues.2 Depending on the nutrient deficiency, symptoms may include pale green leaves, yellowing of leaves, darker than normal green color, purpling of leaves, reddening of leaves, interveinal chlorosis, leaf necrosis, marginal leaf scorch, leaf curling or twisting, poor tillering, stunted plants, and loss of yield potential.
Nutrient Deficiency Symptoms3
Boron: Deficiency symptoms include interveinal chlorosis of the youngest, unfolded leaves. Unfolded new leaves may have a sawtooth appearance. Additionally, the unfolding of leaves may be delayed, increased tillering may be observed, and internodes may be short. Flowering is altered, seed set is poor or sterile, and yield potential is reduced.
Calcium: Deficiency is rare in small grains. If Ca is deficient, plants are severely stunted because of poor root growth—defined by shortened main roots and a proliferation of shortened laterals. New leaves exude a gelatinous-like material that causes the new leaves to stick together. Because Ca deficiency is favored by low pH (<5.2) and low soil Ca, aluminum (Al) and Mn toxicity symptoms are likely to be observed before Ca deficiency symptoms.
Copper: The initial symptom of Cu deficiency is a general wilting of the entire plant at early tillering. A proliferation of tillering may occur in severely deficient plants during stem elongation and plants may be lighter in color. Leaf tips may suddenly die, wither, or curl while the leaf base remains green. Leaves may not unfold when deficiency is severe and fewer grain heads emerge. Grain heads may be filled at base, shriveled in the middle, and withered at the tip.
Iron: Newest leaves are initially affected and become chlorotic. The leaves have an alternating green and yellow longitudinal interveinal striping (chlorosis). The newest leaves may become white when deficiencies are severe. Deficiencies are more common on calcareous soils or after heavy lime applications.
Magnesium: Deficiency initially appears as interveinal chlorosis on older leaves. As the deficiency intensifies, the symptoms progress upward to newer leaves which appear pale. The newest leaves become chlorotic and do not unfold, which results in a twisted appearance. Older leaves may become reddish-purple, and the tips and margins of affected leaves may die. Oldest symptomatic leaves may fall off the plants. Root system is poorly developed.
Manganese: Deficient plants are chlorotic with greenish-gray spots on older leaves. Symptoms may eventually appear on the uppermost recently mature leaves as interveinal chlorosis (streaked) at the base of the leaf while leaf tips may remain green. Leaves with severe Mn deficiency may kink or droop. Deficiencies are rare on wheat grown on soils with a pH of 6.0 to 6.3; however, deficiencies have been observed on Coastal Plain Soils with pH values above 6.3.
Molybdenum: Deficiency is somewhat dependent on N availability. Under low applied N, Mo deficient plants appear limp compared to normal stature of plants with adequate Mo. With high applied N, Mo deficient plants are paler green. If high foliar rates of N are applied to Mo deficient plants, the tips of old leaves may be burned. Middle leaves have a longitudinal yellow striping. Delayed maturity and empty heads may occur under severe deficiencies.
Nitrogen: Nitrogen deficient wheat plants are pale green to yellow with chlorosis beginning on lower leaves and gradually progressing upwards. Cell growth, division, and protein synthesis may be slowed. Plants may have spindly stems and growth may be slowed. Supplemental N applications can help overcome the condition.
Phosphorus: Phosphorus deficient plants remain green and may be darker green than plants with sufficient P. Leaf tips may die when shortages are severe, and some leaves may develop a purple or red discoloration. Poor tillering, slow growth and maturity, and thin stems are other symptoms of P deficiency.
Potassium: Symptoms appear first as chlorosis on older leaves before progressing upward on the plants. Leaves eventually become streaked with a scorched appearance along the leaf margins. Chlorotic areas may develop throughout the leaf. Some fast-maturing, high-yielding wheat products may develop symptoms on young leaves. Plants may be weak and subject to lodging. Some diseases are more common when K is deficient.
Sulfur: Deficiency mimics N deficiency with light green to yellowish leaves. However, the whole plant is pale with S deficiency and the youngest leaves have more chlorosis than with N deficiency. Sulfur deficiency is more common in well-drained, coarse-textured, low organic matter, mineral soils.
Zinc: Deficiency appears as interveinal chlorosis on the most recently developed leaves. Plants are stunted and produce few tillers. Leaves may turn white and die if deficiency is severe.
Sources
1Held, A. 2024. Farming 101: Planting wheat. Successful Farming. https://www.agriculture.com/crops/wheat/farming-101-planting-wheat
2Silva, G. 2016. Identifying nutrient deficiency symptoms in field crops. Michigan State University Extension. https://www.canr.msu.edu/news/identifying_nutrient_deficiency_symptoms_in_field_crops
3Snowball, K. and Robson, A.D. 1991. Nutrient deficiencies and toxicities in wheat: A guide for field identification. CIMMYT. https://repository.cimmyt.org/server/api/core/bitstreams/13de6c7e-2105-4491-849b-8d0acd1e654e/content
Additional Resources
WSU Dryland Cropping Systems Team. Wheat & small grains. Washington State University. https://smallgrains.wsu.edu/soil-and-water-resources/essential-nutrients/
Web sources verified 12/23/24. 1714_454851
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