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By Greg LaBarge
When walking fields, we hope to find deep dark green leaves, but we sometimes have off-colored leaves that are light green to yellow-brown. Off-colored plants can result from disease, insect, or nutrient deficiency. If we do not see evidence of insects or diseases, we start to focus on nutrients. Foliar symptoms of nutrient deficiencies often look similar at first glance. Still, we can narrow the nutrient possibilities by closely observing the leaf’s discolored pattern and the location of affected leaves on the plant.
Table 1 lists nutrients and foliar deficiency symptoms in corn, soybean, and wheat. Two words, “chlorosis” or “chlorotic,” frequently appear in the table. Both terms describe when leaves start yellowing and progress to brown dead tissue over time.
The best practice is to confirm nutrient deficiencies using a tissue test result and possibly a soil test. Relative to soil pH, micronutrient soil tests are not as reliable, but complimenting plant analysis with a soil test can add confidence in diagnosis where both values are low compared to expected results. Taking samples from an affected and a non-affected area of the same field provides a useful in-field comparison.
The most common Ohio soil and crop combinations for micronutrient deficiencies to occur are:
- Manganese in peat and muck soils with a pH >6.2 in soybean, wheat, and corn.
- Zinc in peat muck or mineral soils (with high soil test P) and pH>6.5 in soybean and corn.
- Boron in sandy or highly weathered soils with low OM soils in alfalfa and clover.
Once you identify a nutrient deficiency, take time to determine the cause. Nutrient deficiencies can occur under various soil, moisture, and temperature conditions that impact root growth, thereby limiting nutrient uptake. For example, sidewall compaction, general field compaction, root diseases, or where soils are flooded, dry, or cold can lead to foliar nutrient deficiency symptoms even though adequate soil nutrients are available. In 2025, variable soil conditions for planting may have limited root growth and nutrient uptake. If soil temperature or moisture is the primary cause of limited root growth, the off-colored symptoms will disappear quickly on new growth once conditions improve and roots recover.
Plant tissue testing is the best way to confirm what nutrient is leading to the off-colored symptoms in crops. A recent article https://ocj.com/2025/06/plant-tissue-testing/ provides some insights into tissue testing and sufficiency guidelines for commonly grown crops.
Table 1. Foliar symptoms of nutrient deficiencies.
| Crop | |||
| Nutrient | Corn | Soybean | Alfalfa |
| Nitrogen | Early season symptom is general chlorosis of the entire plant. Late-season chlorosis is an inverted V starting at the leaf tip on lower leaves and then moving up the plant. | Pale green to yellow leaves. Plant discoloration is relatively uniform on the plant. | Stunted plants are light green, with rounded leaflets showing yellowing tips. Lower leaves turn brown and then fall off. |
| Potassium | Chlorosis starts at the leaf tip and then moves along the leaf edge on older leaves. | Chlorosis of the leaf tips, which progresses along the leaf margin. Symptoms occur on both new and old leaves but tend to be more common on older leaves | Stunted plant. Yellow to white spots along leaf margins and tips. Older leaves show symptoms first. |
| Sulfur | Chlorosis is visible on newer leaves. | Stunted plants. Chlorosis is visible on newer leaves. | Leaves, including veins, turn pale green to yellow. Young leaves are affected first. |
| Manganese | Interveinal chlorosis on newly expanding upper leaves. Severe cases show elongated white streaks. | Interveinal chlorosis on new expanding upper trifoliate | Interveinal chlorosis with spots of dead tissue. |
| Zinc | Vertical striping of newer upper leave between the midrib and leaf margin. | Stunted plants that have light green to yellow interveinal chlorosis of leaves. Lower leaves may turn bronze and drop. | Stunted growth with interveinal chlorosis that has spots of dead tissue. |
| Boron | Irregular white spots between veins can develop into stripes with a waxy, raised appearance. | Not been documented in Ohio. | Stunted growth with leaf tip or base growth distortion—dead terminal bud. Leaves near the growing point are yellow and sometimes reddened, with healthy lower leaves. |
