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Nutrient Deficiencies and Application Injuries in Field Crops

Integrated Pest ManagementNutrient DeficienciesandApplication InjuriesinField CropsJohn SawyerDepartment of AgronomyIPM 42 Revised July 2004 Nitrogen deficiency in cornPotassium (K) deficiency is first seen as a yellowingand necrosis of the corn leaf margins, beginning on thelower leaves. Symptoms usually don t appear for sometime after planting (about 4 to 6 weeks, around the V6growth stage). If the deficiency persists, symptomsprogress up the plantbecause potassium ismobile in the plantand translocates fromold to young potassiumdeficiency is severe,older leaves turnyellow with tissuenecrosis along themargins, but the uppernew leaves may remaingreen.

Integrated Pest Management Nutrient Deficiencies and Application Injuries in Field Crops John Sawyer Department of Agronomy IPM 42 Revised July 2004

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Transcription of Nutrient Deficiencies and Application Injuries in Field Crops

1 Integrated Pest ManagementNutrient DeficienciesandApplication InjuriesinField CropsJohn SawyerDepartment of AgronomyIPM 42 Revised July 2004 Nitrogen deficiency in cornPotassium (K) deficiency is first seen as a yellowingand necrosis of the corn leaf margins, beginning on thelower leaves. Symptoms usually don t appear for sometime after planting (about 4 to 6 weeks, around the V6growth stage). If the deficiency persists, symptomsprogress up the plantbecause potassium ismobile in the plantand translocates fromold to young potassiumdeficiency is severe,older leaves turnyellow with tissuenecrosis along themargins, but the uppernew leaves may remaingreen.

2 Potassium-deficient corn tendsto lodge late in thegrowing season due topoor stalk deficiencyis favored by conditionsthat limit early rootgrowth, development,and activity rootpruning, dry soil,compacted soil, seedtrench side-wallsmearing; wet soil;sandy soil; organic soil;strongly geologically-weathered soils;potassium appliedwhere plant rootscannot absorb it; largeamounts of potassiumremoved by a preceding crop; and some tillage systemssuch as ridge-tillage and no-tillage, especially in a dryyear and on soil with low levels of subsoil (Ca) deficiency israre in corn. It has not beenverified in Iowa.

3 If deficient,leaf tips stick to the nextlower leaf, creating a ladder-like appearance. Plants maybe severely stunted becausecalcium is immobile in theplant; it is not translocatedfrom old to growing planttissue that needs soil pH and acid soilproblems like excessive levelsof soluble aluminum andNutrient Deficiencies in cornNitrogen (N) deficiency (pictures on front-page)causes pale, yellowish-green corn plants with spindlystalks. Because nitrogen is a mobile Nutrient in theplant, symptoms begin on the older, lower leaves andprogress up the plant if the deficiency persists.

4 Symp-toms appear on leaves as a v-shaped yellowing, startingat the tip and progressing down the midrib toward theleaf base. The condition is favored by cold or saturatedsoil; dry soil, particularly after mid-season; largeamounts of low-nitrogen residue; sandy soil; inad-equate fertilization; leaching from heavy rainfall; andflooded or ponded soil when the temperature is (P)deficiency is usuallyvisible on young cornplants. It readilymobilizes andtranslocates in theplant. Plants are darkgreen with reddish-purplish leaf tips andmargins on olderleaves. Newlyemerging leaves willnot show the colora-tion.

5 Phosphorus-deficient plants aresmaller and growmore slowly than doplants with adequatephosphorus. Defi-ciency symptomsnearly always disap-pear when plantsgrow to three feet ortaller. Some cornhybrids tend to showpurple colors at earlystages of growth eventhough phosphorusnutrition is adequate,yet other hybrids donot show the colorsymptoms even though inadequate phosphorusseverely limits yields. Phosphorus deficiency is favoredby cold soils that are too wet or too dry; phosphorusapplied where plant roots cannot absorb it; restrictedroot growth in compacted soils; and roots injured byinsects, herbicides, fertilizers, or deficiencyPotassium deficiencyCalcium deficiencymanganese are more likely to occur before calciumdeficiency symptoms appear.

6 Calcium deficiency isfavored by very low soil pH, below on mineral soilsand on organic soils; non-limed, highly weatheredacid soils; or by very high magnesium and potassiumand very low calcium on the cation exchange (Mg) deficiencyis first seen asyellow to whiteinterveinalstriping of thelower cornleaves. Dead,round spotssometimesfollow, whichgive theimpression of beaded streaking. Older leaves becomereddish-purple, and the tips and edges may becomenecrotic if the deficiency is severe. This happens becausemagnesium is mobile in the plant and is translocatedfrom old to new plant tissue.

7 Magnesium deficiency isfavored by very acid, sandy soils in regions of moderateto high rainfall where magnesium has been extensivelyleached from the soil profile. On soils marginal in cropavailable magnesium, deficiency can be induced by highsoil potassium levels or high rates of applied (S) deficiencyshows on small corn plantsas a general yellowing ofthe foliage, similar tonitrogen of the youngerupper leaves is morepronounced with sulfurdeficiency than withnitrogen deficiencybecause sulfur is noteasily translocated in plantsanddelayedmaturityalso theyoungestleaves may occur.

8 This deficiency is favored by acidsandy soils; low soil organic matter; and cold - drysoils in the spring that delay the release of sulfur fromorganic matter. Early-season symptoms may disappearas temperature and moisture conditions improve formineralization of sulfur from organic matter, or cornroots reach plant-available sulfate contained within thesoil (Mo) deficiency (no picture) is rarely, ifever, found in corn. It has not been identified in it occurs, however, older leaves become necrotic atthe tip, along the margins, and between the veins. Thiscondition is favored by very low soil pH and stronglyweathered soils, conditions not normally found in (B) deficiency (no picture) is rare in corn.

9 It hasnot been verified in Iowa. Leaves have small dead spotsand are brittle. Boron is not readily translocated in theplant and as a result upper internodes do not and ear shoots are reduced and may not is very sensitive to boron fertilizer. Boron toxicitycan result if fertilizer is applied at rates above recom-mendations, or row applied. Deficiency is favored bydrought; sandy soils that are low in organic matter; andhigh soil pH. Drought reduces the release of boronfrom organic matter, but lack of water also delays earshoot emergence and possible pollination; therefore,symptoms may occur simultaneously and could beconfused with each (Cu) deficiency (no picture) is rare in corn.

10 Ithas not been verified in Iowa. The youngest leaves areyellow as they come out of the whorl, and the tips maydie. Copper is relatively immobile in the plant. Leavesbecome streaked, causing an appearance that is similarto iron deficiency. The stalk is soft and limp. Somenecrosis of older leaf edges occurs as it does in cases ofpotassium deficiency. Copper deficiency is favored byorganic soils (very high soil organic matter) and byhigh soil pH ( ).Iron (Fe) deficiencyturns the interveinalarea along the length ofthe upper leaves palegreen to nearly has not been verifiedin Iowa.


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