Fertilizer Injury (UAN) of Soybean
Foliar application of liquid urea-ammonium nitrate (UAN) fertilizer may burn soybean seed during in-furrow applications and leaf tissue during foliar applications, even at low rates. Seed injury may reduce seedling emergence and stand. Foliar symptoms occur only where UAN contacts plant tissue and includes irregularly-shaped necrotic and tan to bleached tissue. This injury may be confused for foliar PPO herbicide injury or diseases such as Phyllosticta leaf spot. Injured plants may also become stunted and show reduced growth.
Foliar symptoms of liquid urea-ammonium nitrate (UAN) fertilizer.
Adam Sisson
Foliar symptoms of liquid urea-ammonium nitrate (UAN) fertilizer.
Adam Sisson
Soybean plants often recover from the injury; however, reduced plant growth and yield may occur with even minor seed or leaf burn. Soil moisture greatly determines the extent of fertilizer injury to seed. Dry soils often result in the most severe injury cases as moisture aids in diluting and carrying the fertilizer away from the seed.
To reduce fertilizer injury, fertilizer application in dry conditions should be avoided, and the fertilizer should not make direct contact with the plant.
Prepared and reviewed by the Science for Success team and the Integrated Pest Management Program at Iowa State University.
Foliar symptoms of liquid urea-ammonium nitrate (UAN) fertilizer.
Foliar symptoms of liquid urea-ammonium nitrate (UAN) fertilizer.
Foliar symptoms of liquid urea-ammonium nitrate (UAN) fertilizer.
Foliar symptoms of liquid urea-ammonium nitrate (UAN) fertilizer.
Foliar symptoms of liquid urea-ammonium nitrate (UAN) fertilizer.
Gallery images courtesy Adam Sisson.
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