Integrated Pest Management Nutrient Deficiencies and Application Injuries in Field Crops John Sawyer Department of Agronomy Nitrogen deficiency in corn IPM 42 Revised July 2004 Nutrient deficiencies in corn Potassium (K) deficiency is first seen as a yellowing and necrosis of the corn leaf margins, beginning on the Nitrogen (N) deficiency (pictures on front-page) lower leaves. Symptoms usually don’t appear for some causes pale, yellowish-green corn plants with spindly time after planting (about 4 to 6 weeks, around the V6 stalks. Because nitrogen is a mobile nutrient in the growth stage). If the deficiency persists, symptoms plant, symptoms begin on the older, lower leaves and progress up the plant progress up the plant if the deficiency persists. Symp- because potassium is toms appear on leaves as a v-shaped yellowing, starting mobile in the plant at the tip and progressing down the midrib toward the and translocates from leaf base. The condition is favored by cold or saturated old to young leaves. soil; dry soil, particularly after mid-season; large When potassium amounts of low-nitrogen residue; sandy soil; inad- deficiency is severe, equate fertilization; leaching from heavy rainfall; and older leaves turn flooded or ponded soil when the temperature is warm. yellow with tissue necrosis along the margins, but the upper Phosphorus (P) new leaves may remain deficiency is usually green. Potassium- visible on young corn deficient corn tends plants. It readily to lodge late in the mobilizes and growing season due to translocates in the poor stalk strength. plant. Plants are dark Potassium deficiency green with reddish- is favored by conditions purplish leaf tips and that limit early root margins on older growth, development, leaves. Newly and activity – root emerging leaves will pruning, dry soil, not show the colora- compacted soil, seed tion. Phosphorus- trench side-wall deficient plants are smearing; wet soil; smaller and grow sandy soil; organic soil; more slowly than do strongly geologically- plants with adequate weathered soils; phosphorus. Defi- potassium applied ciency symptoms where plant roots nearly always disap- Potassium deficiency cannot absorb it; large pear when plants amounts of potassium grow to three feet or removed by a preceding crop; and some tillage systems taller. Some corn such as ridge-tillage and no-tillage, especially in a dry hybrids tend to show year and on soil with low levels of subsoil potassium. purple colors at early stages of growth even though phosphorus Calcium (Ca) deficiency is nutrition is adequate, rare in corn. It has not been Phosphorus deficiency yet other hybrids do verified in Iowa. If deficient, not show the color leaf tips stick to the next symptoms even though inadequate phosphorus lower leaf, creating a ladder- severely limits yields. Phosphorus deficiency is favored like appearance. Plants may by cold soils that are too wet or too dry; phosphorus be severely stunted because applied where plant roots cannot absorb it; restricted calcium is immobile in the root growth in compacted soils; and roots injured by plant; it is not translocated insects, herbicides, fertilizers, or cultivation. from old to growing plant tissue that needs calcium. Low soil pH and acid soil problems like excessive levels of soluble aluminum and Calcium deficiency manganese are more likely to occur before calcium leaves may occur. This deficiency is favored by acid deficiency symptoms appear. Calcium deficiency is sandy soils; low soil organic matter; and cold - dry favored by very low soil pH, below 5.0 on mineral soils soils in the spring that delay the release of sulfur from and 4.8 on organic soils; non-limed, highly weathered organic matter. Early-season symptoms may disappear acid soils; or by very high magnesium and potassium as temperature and moisture conditions improve for and very low calcium on the cation exchange complex. mineralization of sulfur from organic matter, or corn roots reach plant-available sulfate contained within the soil profile. Magnesium (Mg) deficiency Molybdenum (Mo) deficiency (no picture) is rarely, if is first seen as ever, found in corn. It has not been identified in Iowa. yellow to white If it occurs, however, older leaves become necrotic at interveinal the tip, along the margins, and between the veins. This striping of the condition is favored by very low soil pH and strongly lower corn weathered soils, conditions not normally found in the leaves. Dead, Midwest. round spots sometimes Boron (B) deficiency (no picture) is rare in corn. It has Magnesium deficiency follow, which not been verified in Iowa. Leaves have small dead spots give the and are brittle. Boron is not readily translocated in the impression of beaded streaking. Older leaves become plant and as a result upper internodes do not elongate. reddish-purple, and the tips and edges may become Tassels and ear shoots are reduced and may not emerge. necrotic if the deficiency is severe. This happens because Corn is very sensitive to boron fertilizer. Boron toxicity magnesium is mobile in the plant and is translocated can result if fertilizer is applied at rates above recom- from old to new plant tissue. Magnesium deficiency is mendations, or row applied. Deficiency is favored by favored by very acid, sandy soils in regions of moderate drought; sandy soils that are low in organic matter; and to high rainfall where magnesium has been extensively high soil pH. Drought reduces the release of boron leached from the soil profile. On soils marginal in crop from organic matter, but lack of water also delays ear available magnesium, deficiency can be induced by high shoot emergence and possible pollination; therefore, soil potassium levels or high rates of applied potassium. symptoms may occur simultaneously and could be confused with each other. Sulfur (S) deficiency shows on small corn plants Copper (Cu) deficiency (no picture) is rare in corn. It as a general yellowing of has not been verified in Iowa. The youngest leaves are the foliage, similar to yellow as they come out of the whorl, and the tips may nitrogen deficiency. die. Copper is relatively immobile in the plant. Leaves Yellowing of the younger become streaked, causing an appearance that is similar upper leaves is more to iron deficiency. The stalk is soft and limp. Some pronounced with sulfur necrosis of older leaf edges occurs as it does in cases of deficiency than with potassium deficiency. Copper deficiency is favored by nitrogen deficiency organic soils (very high soil organic matter) and by because sulfur is not high soil pH (above easily translocated in the 7.5). plant. Stunting Iron (Fe) deficiency of plants turns the interveinal and area along the length of delayed the upper leaves pale maturity green to nearly white. also are It has not been verified symp- in Iowa. Iron is immo- toms. bile and is not translo- Interveinal cated from old to chlorosis young plant tissue. of the This deficiency is rare youngest on corn because of its Sulfur deficiency low iron requirement, Iron deficiency and it only occurs on high pH soils. Iron deficiency is Fertilizer injury to corn favored by calcareous soils with a high soil pH in the surface soil and by cold, wet, poorly aerated soils. and soybean Anhydrous ammonia (NH3) vapor damage to leaves Manganese (Mn) can occur when sidedressing ammonia if the applicator deficiency symptoms are knives are not clear-cut. It has not near or been verified on corn in above the Iowa. Newly emerged soil surface leaves become olive- and there is green and may become escape of slightly streaked. If the ammonia condition is severe, during deficient leaves become application. elongated with white Corn plants streaks that turn brown usually in the center, deteriorate outgrow the and fall out. Manganese damage if is relatively immobile in only a the plant. Manganese portion of deficiency is favored by the leaves is Anhydrous ammonia vapor damage high soil pH; sandy soils damaged. that are high in organic matter, and peat or muck soils. Manganese deficiency Non-pressure nitrogen solutions (urea-ammonium nitrate solution, 28 or 32% UAN) broadcast on top of growing corn can burn leaf tissue. The solutions tend Zinc (Zn) deficiency to move towards the leaf tip and margins, resulting in in corn causes greater burning of those leaf areas. Corn plants usually interveinal, light outgrow the damage if only a portion of the leaves is striping or a whitish injured. However, leaf damage and potential yield band beginning at impacts the base of the leaf increase with and extending higher towards the tip. The application margins of the leaf, rates and the midrib area, and larger plants. the leaf tip usually remain green. Plants are stunted because internodes are shortened. Zinc is relatively immobile in the plant. Severe zinc deficiency may result in new leaves that are nearly white, Zinc deficiency an effect termed “white bud.” Plants frequently outgrow zinc deficiency unless it is severe. Zinc deficiency is favored by high soil pH; low organic matter soils with high soil pH; cool, wet soil; and high phosphorus fertilizer applications on soils that are marginal in zinc availability, although high soil phos- phorus levels alone don’t create zinc deficiency. Broadcast solution nitrogen Non-pressure nitrogen solutions (urea-ammonium Anhydrous ammonia injury results in uneven corn nitrate solution, 28 or 32% UAN) broadcast on top of seedling emergence, slow plant growth, plants with a growing soybean can burn leaf tissue. Application even spiked and blue- at low rates can cause tissue damage. Soybean plants green color appear- usually outgrow the damage if only a portion of the ance, and wilting of leaves is injured. seedlings in dry weather. Ammonia injury is detected more frequently in dry weather because roots are slow to develop; if a portion Broadcast nitrogen solution Granular urea applied on top of growing corn results in some granules falling in the whorl and lodging in leaf axils.