Nutrient Management a self-study course from the MSU Extension Service Continuing Education Series 9 Nutrient Management Module No. 9 CCA 1.5 NM Plant Nutrient CEU Functions and Deficiency and Toxicity Symptoms

by Ann McCauley, Soil Scientist; Clain Jones, Extension Soil Fertility Specialist; and Jeff Jacobsen, College of Agriculture Dean

Introduction This module is the ninth in a series of extension materials designed to provide extension agents, Certified Crop Advisers (CCAs), consultants, and producers with pertinent information on nutrient management issues. To make the learning ‘active,’ and to provide credits to CCAs, a quiz accompanies this module. In addition, realizing that there are many other good information sources including previously developed extension materials, books, web sites, and professionals in the field, we have provided a list of additional resources and contacts for those wanting more in-depth information about plant nutrient functions and deficiency and toxicity symptoms.

Objectives After reading this module, the reader should be able to:

1. Identify and diagnose common plant nutrient deficiency and toxicity symptoms 2. Know potential limitations of visual diagnosis 3. Understand how to use a key for identifying deficiency symptoms 4. Distinguish between mobile and immobile nutrient deficiencies

4449-9 May 2009 Background Discussed in Nutrient Management # Module 2, Plant Nutrition and Soil Q&A 1 Fertility, plants require essential nutrients for normal functioning and growth. A How is plant analysis used plant’s sufficiency range is defined as the range of nutrient necessary to meet the as a diagnostic tool? plant’s nutritional needs and maximize Plant analysis consists of testing growth (Figure 1). The width of this range nutrient concentrations in specific will depend upon individual plant species plant parts during specific growth and the particular nutrient. Nutrient stages (Jacobsen and Jasper, 1991). If levels outside of a plant’s sufficiency nutrient concentrations in a sample range will cause overall crop growth are below or above an established and health to decline due to either a sufficiency range, then the plant is deficiency or toxicity. Nutrient deficiency deficient or in excess for that element. occurs when an essential nutrient is not Plant analyses can be performed available in sufficient quantity to meet relatively quickly in the field using the requirements of a growing plant. semi-quantitative test kits or more Toxicity occurs when a nutrient is in extensively in a laboratory (Havlin et excess of plant needs and decreases plant al., 1999). As a diagnostic tool, plant growth or quality. Common nutrient analysis improves the chances of deficiencies in Montana and Wyoming making a correct diagnosis and can be are nitrogen (N) and phosphorus (P), particularly useful in identifying hidden with some deficiencies of potassium hunger or pseudo deficiencies. (K), sulfur (S), boron (B), chloride (Cl), copper (Cu), iron (Fe), manganese (Mn), and most likely occurs as a result of the and zinc (Zn). Micronutrient deficiencies over-application of fertilizer or manure. are fairly uncommon with deficiencies The three basic tools for diagnosing of B, Cl, Fe, and Zn occurring most nutrient deficiencies and toxicities are often (Nutrient Management Module 1) soil testing; 2) plant analysis; and 3) 7, Micronutrients: Cycling, Testing and visual observations in the field. Both soil Fertilizer Recommendations). Nutrient testing (Nutrient Management Module 1, toxicity is less common than deficiency Soil Sampling and Laboratory Selection) and plant analysis (Q&A #1 and #2) are Deficiency range Sufficiency range Toxicity range quantitative tests that are compared to the sufficiency range for a particular crop. Visual observation, on the other hand, is a qualitative test and is based on symptoms such as stunted growth or a yellowing of leaves occurring as a result of nutrient stress. This module focuses on visual nutrient deficiency and toxicity symptoms observed in common crops grown in Montana and Wyoming. Visual Symptoms as a P l a n t G r o w h d H e Amount of Available Nutrient Diagnostic Tool Figure 1. Relationship between plant growth and Interpreting visual nutrient deficiency health and amount of nutrient available (Brady and and toxicity symptoms in plants can be Weil, 1999). difficult and plant analysis or soil testing 2 Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms is necessary to confirm nutrient stress. and corrective actions may or may not be Precautions in identifying nutrient stress effective. Therefore, regular soil or plant symptoms include the following: testing is recommended for the prevention 1. Many symptoms appear similar. For and early diagnosis of nutrient stress. instance, nitrogen (N) and sulfur (S) If visual symptoms are observed, deficiency symptoms can be very alike, record which crop(s) are affected, their depending upon placement, growth location with respect to topography, stage, and severity of deficiencies. aspect, and soil conditions, a detailed 2. Multiple deficiencies and/or toxicities description of symptoms, and time of season that the symptoms first appeared. can occur at the same time. More than Affected field locations can be marked and one deficiency or toxicity can produce monitored over time using either flagging symptoms, or possibly a deficiency or GPS readings. This information will be of one nutrient can induce the useful in preventing nutrient stress for excessiveness of another (i.e., excessive subsequent years. P causing Zn deficiency). 3. Crop species, and even some cultivars of the same species, differ in their ability to adapt to nutrient deficiencies # and toxicities. For example, corn Q&A 2 is typically more sensitive to a Zn deficiency than barley NM( 7). I suspect a nutrient deficiency. How do I 4. Pseudo (false) deficiency symptoms collect a plant sample for submission to (visual symptoms appearing similar to nutrient deficiency symptoms). an analytical laboratory? Potential factors causing pseudo If you suspect nutrient stress, sample when symptoms deficiency include, but are not limited first appear. To ensure quality results, samples should be to, disease, drought, excess water, taken from comparable locations (similar topography, genetic abnormalities, herbicide and aspect, and soil type) and at the same time of day. When pesticide residues, insects, and soil testing samples for plant analysis, it is important to collect compaction. the part of the plant that will give the best indication of the nutrient status of the whole plant. The latest mature 5. Hidden hunger. Plants may be nutrient leaf is typically used, however, appropriate plant parts deficient without showing visual clues. to test will vary with crop type and growth stage (see 6. Field symptoms appear different than Appendix for additional resources). Collect numerous ‘ideal’ symptoms. Many of the plants (20-30) subsamples of parts from plants that appear shown in this module as photographs both abnormal and healthy, if possible. Subsamples may were grown under controlled nutrient be combined for one sample. To gather plant samples, conditions, and deficiency/toxicity use a clean plastic or paper container (metal containers symptoms observed in the field may can contaminate samples). If the samples have soil, or may not appear as they do here. fertilizer, or spray residues on them, clean gently with Experience and knowledge of field a dry brush or with deionized or distilled water. Do not history are excellent aids in determining prolong washing because it can leach nutrients out of the causes for nutrient stress. tissue. Air-dry samples in the shade in either a paper bag or envelope. To avoid decomposition, do not use plastic In addition to the above precautions, bags or send fresh samples. When mailing samples to the visual observation is also limited by time. laboratory, include type and variety of crop, current and Between the time a plant is nutrient past crop management practices, irrigation frequency deficient (hidden hunger) and visual (if applicable), soil type (if known), visual appearance of symptoms appear, crop health and crops, and any insect or disease problems. productivity may be substantially reduced

Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms 3 Diagnosing Nutrient Deficiencies Plant Nutrient Deficiency Terminology Co m m o n De f i c i e n c y Sy m p t o m s A first step in diagnosing nutrient Burning: severe localized yellowing; deficiencies is to describe what the scorched appearance. symptoms look like. Each deficiency Chlorosis: general yellowing of the symptom must be related to some function plant tissue; lack of chlorophyll. of the nutrient in the plant (Havlin et Generalized: symptoms not limited al., 1999). The role of each essential to one area of a plant, but rather nutrient in the plant is listed in Table 1 spread over the entire plant. of NM 2. Symptoms caused by nutrient deficiencies are generally grouped into five Immobile: not able to be moved from categories: 1) stunted growth; 2) chlorosis; one part of the plant to another. 3) interveinal chlorosis; 4) purplish-red Interveinal Chlorosis: yellowing in coloring; and 5) necrosis. Stunting is a between leaf veins, yet veins remain common symptom for many deficient green. nutrients due to their varied roles in Localized: symptoms limited to one the plant. For example, when nutrients leaf or one section of the leaf or involved in plant functions such as stem plant. elongation, photosynthesis, and protein production are deficient, plant growth Mobile: able to be moved from one is typically slow and plants are small in plant part to another. stature. Chlorosis and interveinal chlorosis Mottling: spotted, irregular, are found in plants deficient of nutrients inconsistent pattern. necessary for photosynthesis and/or Necrosis: death of plant tissue; tissue chlorophyll (green leaf pigment involved browns and dies. in photosynthesis) production. Chlorosis can result in either the entire plant or leaf Stunting: decreased growth; shorter turning light green to yellow, or appear height of the affected plants. more localized as white or yellow spotting. accumulate when plant functions are Interveinal chlorosis disrupted or stressed. This symptom can be is the yellowing of particularly difficult to diagnose because leaf tissue between cool temperatures, disease, drought, veins, with the veins and even maturation of some plants can themselves remaining also cause anthocyanin to accumulate green (Figure 2). (Bennett, 1994). Certain plant cultivars Interveinal chlorosis may also exhibit this purple coloring. occurs when some Necrosis generally happens in later stages nutrients (B, Fe, of a deficiency and causes the parts of the magnesium (Mg), Mn, plant first affected by the deficiency to nickel (Ni), and Zn) are brown and die. Since a number of nutrient deficient. Purplish-red deficiencies can produce similar symptoms, discolorations in plant further evaluation of symptoms related to stems and leaves are particular leaf patterns or locations on the due to above normal plant will be needed to diagnose nutrient Figure 2. Interveinal chlorosis levels of anthocyanin specific deficiencies. These specifics will be (Fe deficiency) (Bennett, (a purple colored discussed in detail later in the module. 1993). pigment) that can 4 Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms Mobile and Immobile Nutrients symptoms may not be listed (see Another initial step in identifying text for detailed descriptions deficiency symptoms is to determine of deficiencies and Appendix whether the deficiency is the result of for resources on specific crop a mobile or immobile nutrient based symptoms). on where the symptom is appearing in the whole plant. Mobile nutrients are Mo b i l e Nu t r i e n t s nutrients that are able to move out of older leaves to younger plant parts when Nitrogen (N) supplies are inadequate. Mobile nutrients Nitrogen is needed by Figure 3. N deficiency plants for the production of include N, P, K, Cl, Mg, and molybdenum in corn leaves (leaves (Mo). Because these nutrients are mobile, proteins, nucleic acids (DNA visual deficiencies will first occur in the and RNA), and chlorophyll. on left are N deficient, older or lower leaves and effects can be Symptoms of N deficiency leaf on right is normal). either localized or generalized. In contrast, are general chlorosis of lower Yellow discoloration and immobile nutrients (B, calcium (Ca), leaves (light green to yellow), stunted growth. Cu, Fe, Mn, Ni, S, and Zn) are not able to stunted and slow growth, Photo courtesy http://www.gov.on.ca/ OMAFRA/english/environment/efp/ move from one plant part to another and and necrosis of older leaves infosheet_16.htm (Ontario Ministry of deficiency symptoms will initially occur in severe cases (Figure 3). N Agriculture and Food) in the younger or upper leaves and be deficient plants will mature localized. Zn is a partial exception to this early and crop quality and yield as it is only somewhat immobile in the are often reduced (Jones, 1998). In cereals, plant, causing Zn deficiency symptoms to yellow discoloration from the leaf tip initially appear on middle leaves and then backward in the form of a “V” is common affect both older and younger leaves as the (Figure 4) (Jacobsen and Jasper, 1991). deficiency develops. Insufficient amounts of N in cereals will also result in few tillers, slender stalks, Identification key short heads, and grains with low protein The ‘key’ on pages 6 and 7 can be content. Leaf curling and small tubers used for identifying nutrient deficiencies are common in potatoes deficient of N. based on common symptoms. The Fields deficient in N can be either uniform key consists of different alternative or patchy in appearance, depending on statements about plant structures and conditions favoring the deficiency. their appearance. If possible, it may be helpful to have a healthy plant on hand for comparison purposes. Beginning at the top of the key, read the first statement and determine whether the statement applies to the plant(s) being evaluated. If the statement describes the plant’s symptoms, proceed along the ‘YES’ arrow to the next statement. If not, follow the ‘NO’ arrow to an alternative statement. Continue this process until the probable nutrient responsible for the deficiency is identified. Although most descriptions in this key are generalized to accommodate common symptoms seen in various crops, bear in mind that deficiency symptoms differ among crop types and plant specific Figure 4. N deficiency in barley. Top leaves are N deficient, bottom leaf is normal.

Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms 5 MOBILE NUTRIENTS

NO Older or lower leaves affected

YES

Effects mostly generalized; NO Effects mostly localized; chlorosis plants dark or light green with or without spotting

YES YES

Plants dark green, often Chlorosis with interveinal developing purple or red color chlorosis; leaves sometimes red or with dead spots YES YES NO PHOSPHORUS (P) MAGNESIUM (Mg) NO

Plants light green with leaves light No interveinal chlorosis; green or yellow; no necrotic spotting chlorotic areas with a burning of leaf margins; spotting sometimes YES along leaf margins YES NITROGEN (N) NO NO POTASSIUM (K)

No interveinal chlorosis; distinct Plants light green; necrotic spotting chlorotic and nectrotic lesions on leaves; pale leaves sometimes (spotting) with abrupt boundary scorched, cupped or rolled between dead and live tissue

YES YES

* MOLYBDENUM (Mo) * CHLORIDE (Cl)

*If symptoms don't meet any of the key descriptions, either go back through the key another time or refer to text for more specific symptom descriptions.

6 Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms IMMOBILE NUTRIENTS

Newer or younger leaves affected; symptoms localized YES

Growing point NO Growing point typically (terminal bud) dies remains alive

YES YES

Chlorosis without NO Young leaves with Young leaves of terminal bud interveinal chlorosis interveinal chlorosis become light green at bases; leaves become twisted and YES YES brittle and die back at growing point; chlorosis of young leaves Young leaves light green; Sharp distinction typically no chlorotic between veins and YES spotting or striping chlorotic areas

BORON (B) NO YES YES NO IRON (Fe) SULFUR (S) NO NO No sharp distinction Young leaves of terminal bud between veins and typically hooked at first, finally chlorotic areas; turning brown and dying back spotty appearance

YES Chlorosis of young leaves; YES tips appear withered and * CALCIUM (Ca) will eventually die MANGANESE (Mn) YES Middle leaves with interveinal chlorosis; stunted growth NOTE: Since nickel (Ni) was * COPPER (Cu) only recently added as an YES essential nutrient, specific Ni deficiency symptoms are not well defined. Common * ZINC (Zn) symptoms include chlorosis (Initial symptoms occur in and interveinal chlorosis in middle leaves, with young and/ younger leaves. or old leaves becoming chlorotic in later stages of deficiency)

Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms 7 Phosphorus (P) exposed areas that have highly eroded or Plants require P for the development weathered soils, or in areas that have been of ATP (energy), sugars, and nucleic acids. leveled, exposing subsoils high in calcium

P deficiency symptoms are usually more carbonate (CaCO3). Crops grown in soils

noticeable in young plants, which have a high in CaCO3 are prone to P deficiency greater relative demand for P than more due to the precipitation of Ca-P insoluble mature plants (Grundon, 1987). Cool minerals. soils during the early growing season may also be a factor causing P deficiency. Potassium (K) P deficient plants generally turn dark Potassium is utilized by plants in the green (both leaves and stems) and appear activation of enzymes and co-enzymes stunted (Figure 5). Older leaves are (specialized proteins serving as catalysts affected first and may acquire a purplish and co-factors), photosynthesis, protein discoloration due to the accumulation of formation, and sugar transport. K sugars in P deficient plants which favor deficiency does not immediately result anthocyanin synthesis; in some cases, leaf in visible symptoms (hidden hunger). tips will brown and die (Figure 6). Plants Initially, there is only a reduction in suffering from P deficiency appear weak growth rate, with chlorosis and necrosis and maturity is delayed. Leaf expansion occurring in later stages (Mengel and and leaf surface area may also be inhibited, Kirkby, 2001). Affected older leaves will causing leaves to curl and be small. Wheat show localized mottled or chlorotic areas and small grains with P deficiency tend with leaf burn at margins (Figure 7). to be stressed and predisposed to root rot diseases, and some cultivars will turn red or purple. In alfalfa, an upward tilting of leaflets may occur. Potato P deficiency symptoms include leaves curling upward and tubers having brown internal specks, often radiating out from the core. P deficiency in corn is usually visual in young plants with leaves turning purple. From a field perspective, P deficiency is likely to occur on tops of ridges or other

Figure 5. P deficiency in alfalfa (left) and normal Figure 6. P deficiency in corn. Leaves alfalfa (right). P deficient leaf is dark green and are purplish (dark areas in photo) stunted. (EB 43, 1991) and tips are brown and necrotic.

8 Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms Chlorotic symptoms typically begin on the However, recent leaf tip, but unlike the ‘V’ effect caused studies have shown by N deficiency, K deficient chlorosis will Cl deficiencies to advance along the leaf margins towards exist in Montana, the base, usually leaving the midrib alive with visual symptoms and green. As the deficiency progresses, observed in winter the entire leaf will yellow. Small white or wheat and durum yellow necrotic spots may also develop, wheat cultivars (Engel beginning along leaf margins (Figure et al., 1998; Engel 8). Another indication of K deficiency is et al., 2001). Plants reduced straw or stalk strength in small with insufficient Cl Figure 8. K deficient (left) and grains and corn, resulting in lodging concentrations show problems, reduced disease resistance, and chlorotic and necrotic normal (right) trifoliates. White reduced winter-hardiness of perennial spotting along spotting occurring along leaf or winter annual crops (Jacobsen and leaves with abrupt margins in deficient leaf. Jasper, 1991). Produced grains will be boundaries between low in protein and appear shriveled. In dead and live tissue (Figure 9). Wilting alfalfa, white spots will appear on leaf of leaves at margins and highly branched edges. Some cultivars, especially barley, root systems are also typical Cl deficient develop excessive numbers of tillers when symptoms, found mainly in cereal crops K is deficient. Due to K’s role in sugar (Mengel and Kirkby, 2001). Cl deficiencies accumulation, root crops (i.e., potatoes, are highly cultivar specific and can be sugarbeets) will have small tubers. easily mistaken for leaf diseases.

Chloride (Cl) Magnesium (Mg) Chloride is required by the plant Magnesium is the central molecule for leaf turgor and photosynthesis. in chlorophyll and is an important co- Until recently, little information was factor for the production of ATP. As documented on Cl deficiencies, as Mg concentrations are sufficient in symptoms were often misdiagnosed as most Montana and Wyoming soils, Mg physiological leaf spot (Engel et al., 2001). deficiencies are not common. Symptoms of Mg deficiency include interveinal chlorosis and leaf margins becoming yellow or reddish-purple while the midrib remains green. In wheat, distinct mottling as yellowish-green patches will occur, and alfalfa leaves may curl and have reddish undersides. Leaves of Mg deficient sugarbeets and potatoes are stiff and brittle and veins are often twisted. Reduced Mg concentrations in wheat forage can lead Figure 7. K deficiency in corn. Older leaves are to grass tetany (low blood serum Mg) in animals chlorotic and leaf edges are burned, but the grazing on winter wheat midrib remains green. (From Bennett, 1993) (Jacobsen and Jasper, 1991).

Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms 9 Molybdenum (Mo) Molybdenum is needed for enzyme activity in the plant and for nitrogen- fixation in legumes. Due to this interrelationship, Mo deficiency symptoms often resemble N deficiency symptoms with stunted growth and chlorosis occurring in legumes. Other symptoms of Mo deficiency include pale leaves that may be scorched, cupped, or rolled. Leaves may also appear thick or brittle, and will eventually wither, leaving only the midrib.

Immobile Nutrients Sulfur (S) As S is an essential constituent of certain amino acids and proteins, S deficiency results in the inhibition of protein and chlorophyll synthesis. S deficiency symptoms can be difficult to diagnose as effects can resemble symptoms of N and Mo deficiencies. In contrast to Figure 9. Cl deficiency in N or Mo deficiency, however, S deficiency hydroponically grown WB881 symptoms initially occur in younger durum wheat. (From R. Engel) leaves, causing them to turn light green to yellow (chlorosis) (Figure 10). In later not displayed. Additionally, plants deficient growth, the entire plant may be pale green. in S tend to be spindly and small and stems Characteristic spots or stripes are generally are often thin. Boron (B) Primary functions of B in plants are related to cell wall formation and reproductive tissue. Plants suffering from B deficiency exhibit chlorotic young leaves and death of the main growing point (terminal bud). In addition to chlorosis, leaves may develop dark brown, irregular lesions that will progress to leaf necrosis in severe cases. Whitish-yellow spots may also form at the bases of leaves. Due to disturbances in cell wall growth, leaves and stems of B deficient plants will become brittle and distorted and leaf tips tend to thicken and curl. Affected plants will grow slowly and appear stunted as a result of shortened internodes (stem segment Figure 10. S deficient wheat plant (left) has light between points where leaves are attached). green leaves and stunted growth as compared to Because B tends to accumulate in normal wheat plant (right). reproductive tissues, flower buds may fail

10 Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms to form or are misshapen, and pollination and seed viability is usually poor in B deficient plants (Jacobsen and Jasper, 1991; Weise, 1993). In alfalfa and canola, B deficiency symptoms include rosetting (the clustering of leaves in crowded circles), yellowing of upper leaves, and poor flowering (Figure 11). A well-documented B deficiency in sugarbeets is crown and heart rot (Mengel and Kirkby, 2001). Along with stunted growth, symptoms include young leaves curling and turning brown or black in color. In later stages of the deficiency, the crown of the beet begins to rot and disease sets in, affecting the whole plant. The healthy part of the beet will be low in sugar.

Iron (Fe) Figure 11. Alfalfa with B deficiency; chlorosis of Iron plays an important role in plant upper leaves and rosetting of leaves near base respiratory and photosynthetic reactions. (From EB 43, 1991). Fe deficiency reduces chlorophyll production and is characterized by interveinal chlorosis with a sharp distinction between veins and chlorotic areas in young leaves (Figure 12). As the deficiency develops, the entire leaf will become whitish-yellow and progress to necrosis. Slow plant growth also occurs. When viewed from a distance, Fe deficient fields exhibit irregularly shaped yellow areas, especially where the subsoil is exposed at the surface (Follett and Westfall, 1992).

Figure 12. Progression of Fe deficiency in wheat leaves. Top leaf normal; middle leaves showing interveinal chlorosis with prominent green veins; and bottom leaf entirely chlorotic. (From Grundon, 1987).

Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms 11 Zinc (Zn) Zinc is needed by plants for growth hormone production and is particularly important for internode elongation. As previously noted, Zn has intermediate mobility in the plant and symptoms will initially show up in middle leaves. Zn deficient leaves display interveinal chlorosis, especially midway between the margin and midrib, producing a striping effect; some mottling may also occur Figure 14. Cu deficiency in wheat: (Figure 13). Chlorotic areas can be pale severely affected (left), moderately green, yellow, or even white. Severe Zn deficiencies will cause leaves to turn gray- affected (center), unaffected (right). white and fall prematurely or die. Because Deficient wheat shows melanosis Zn plays a prominent role in internode with poor grain production and fill. elongation, Zn deficient plants generally exhibit severe stunting. Flowering and seed Calcium (Ca) set is also poor in affected plants. Crop Calcium is a component of plant cell specific symptoms include smaller leaf size walls and regulates cell wall construction. in alfalfa, gray or bronze banding in cereal Ca deficiency is uncommon in many leaves, reduced tiller production in wheat Montana and Wyoming areas due to and other small grains, and abnormal the presence of calcium carbonates grain formation (Wiese, 1993). In cattle, Zn and gypsum in most agriculture soils. deficiencies in forage have been shown to Insufficient Ca can cause young leaves to reduce reproductive efficiency (Paterson, become distorted and turn abnormally dark 2002). Zn deficiency generally does not green. Leaf tips often become dry or brittle affect fields uniformly and deficient areas and will eventually wither and die. Stems usually occur where topsoil has been are weak and germination is poor. removed (Follet and Westfall, 1992). Copper (Cu) Copper is needed for chlorophyll production, respiration, and protein synthesis. Cu deficient plants display chlorosis in younger leaves, stunted growth, delayed maturity (excessively late tillering in grain crops), lodging, and, in some cases, melanosis (brown discoloration). In cereals, grain production and fill is often poor, and under severe deficiency, grain heads may not even form (Figure 14). Cu deficient plants are prone to increased disease, specifically ergot (a fungus causing reduced yield and grain quality); (Solberg et al., 1999). The onset of disease-caused symptoms Figure 13. Zn deficiency displaying striped may confound the identification of Cu deficient symptoms. Winter and spring interveinal chlorosis. wheat are the most sensitive crops to Cu deficiency (Solberg et al., 1999). In the field, Cu deficiency symptoms occur in

12 Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms irregular patches with melanosis being manure. Secondary the most obvious symptom, particularly macronutrient (Ca, in wheat stands. Similar to Zn, forage that Mg, and S) toxicities is deficient in Cu can cause a reduction are rare in this region in the reproductive efficiency of cattle and toxic effects on (Paterson, 2002). crop health have not been documented. Manganese (Mn) Micronutrient toxicities Chloroplasts (plant organelles can occur and are where photosynthesis occurs) are the likely caused by over- most sensitive of cell organelles to Mn application, using deficiency (Mengel and Kirkby, 2001). irrigation water high As a result, a common symptom of Mn in micronutrients deficiency is interveinal chlorosis in or salts, or in areas young leaves (Figure 15). However, unlike where micronutrient Fe, there is no sharp distinction between concentrations are veins and interveinal areas, but rather a abnormally high (i.e., more diffuse chlorotic effect. Two well areas exposed to mining Figure 15. Mn deficient wheat known Mn deficiencies in arable crops are activity or high metal grey speck in oats and marsh spot in peas. minerals in subsoil). In displaying interveinal chlorosis. White streak in wheat and interveinal addition, high amounts brown spot in barley are also symptoms of non-essential elements such as arsenic of Mn deficiency (Jacobsen and Jasper, (As), cadmium (Cd), and lead (Pb) can be 1991). directly toxic to plants and livestock or cause a nutrient imbalance in the plant, Nickel (Ni) in which essential nutrient deficiencies or Nickel is required by plants for toxicities may possibly occur. proper seed germination. Additionally, Ni is the metal component in urease, an a n d enzyme that catalyzes the conversion of N, P, K Plants with excess N turn a deep urea to ammonium (Havlin et al., 1999). green color and have delayed maturity. Research has shown Ni to be beneficial Due to N being involved in vegetative for N metabolism in legumes and other growth, excess N results in tall plants with plants in which ureides are important weak stems, possibly causing lodging to in metabolism (Gerendas et al., 1999). occur. New growth will be succulent and Though Ni deficiency symptoms are plant transpiration high (low water use not well documented and believed to be efficiency) (Jacobsen and Jasper, 1991). non-existent in Montana and Wyoming, N toxicity is most evident under dry symptoms include chlorosis and conditions and may cause a burning effect. interveinal chlorosis in young leaves that Plants fertilized with ammonium (NH +)- progresses to plant tissue necrosis. Other 4 based fertilizers may exhibit NH + toxicity, symptoms include poor seed germination 4 indicated by reduced plant growth, lesions and decreases in crop yield. occurring on stems and roots, and leaf margins rolling downward. Diagnosing Nutrient Toxicities Excess P indirectly affects plant growth As insufficient nutrient content can by reducing Fe, Mn, and Zn uptake; thus, cause visual symptoms to occur in plants, potentially causing deficiency symptoms so too can an excess. In Montana and of these nutrients to occur (see specific Wyoming, macronutrient (N, P, and K) deficiency descriptions). Zn deficiency is toxicities most often occur as a result most common under excess P conditions. of the over-application of fertilizers or

Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms 13 Due to a cation imbalance, K toxicity can Summary cause reduced uptake and subsequent Nutrient deficiencies and toxicities deficiencies of Mg, and in some cases, Ca cause crop health and productivity (see Mg and Ca deficiency descriptions). to decrease and may result in the appearance of unusual visual symptoms. Mi c r o n u t r i e n t s Understanding each essential nutrient’s For many crops, the sufficiency role and mobility in the plant can help in range between deficiency and toxicity determining which nutrient is responsible is narrower for micronutrients than for a deficiency or toxicity symptom. macronutrients (Brady and Weil, 1999). General deficiency symptoms include This is particularly true for B in which stunted growth, chlorosis, interveinal the average sufficiency and toxicity ranges chlorosis, purple or red discoloration, and for various crops overlap one another: necrosis. Deficiencies of mobile nutrients 10-200 ppm (sufficiency range) and 50- first appear in older, lower leaves, whereas 200 ppm (toxicity range) (Jones, 1998). deficiencies of immobile nutrients will B toxicity results in chlorosis followed by occur in younger, upper leaves. Nutrient necrosis. Symptoms begin at the leaf tip toxicity is most often the result of over- and margins and spread toward the midrib. application, with symptoms including As the toxicity progresses, older leaves will abnormal growth (excessive or stunted), appear scorched and fall prematurely. In chlorosis, leaf discoloration, and necrotic sugarbeets, a yellow-tinted band will occur spotting. When in excess, many nutrients around leaf margins (Ulrich et al., 1993). will inhibit the uptake of other nutrients, Other micronutrients causing thus potentially causing deficiency potential toxicity symptoms include Cu, symptoms to occur as well. Mn, Mo, Ni, and Zn. Studies suggest As a diagnostic tool, visual observation excess Cu will displace Fe and other can be limited by various factors, including metals from physiologically important hidden hunger and pseudo deficiencies, centers, causing chlorosis and other Fe and soil or plant testing will be required deficiency symptoms, such as stunted to verify nutrient stress. Nonetheless, the growth, to appear (Mengel and Kirkby, evaluation of visual symptoms in the field 2001). Mn toxicity symptoms are generally is an inexpensive and quick method for characterized by blackish-brown or red detecting potential nutrient deficiencies or spots on older leaves and an uneven toxicities in crops, and learning to identify distribution of chlorophyll, causing symptoms and their causes is an important chlorosis and necrotic lesions on leaves. skill for managing and correcting soil While Mo toxicity does not pose serious fertility and crop production problems. crop problems (crops may appear stunted with yellow-brown leaf discolorations), excess amounts of Mo in forage have been found to be toxic to livestock (Havlin et al., 1999). Similar to excess Cu, high Ni concentrations can cause Fe to be displaced. In turn, interveinal chlorosis may appear in new leaves of Ni toxic plants and growth may be stunted. Zn toxicity is not common, but can occur on very saline soils. Symptoms include leaves turning dark green, chlorosis, interveinal chlorosis, and a reduction in root growth and leaf expansion. Excess Zn may induce an Fe deficiency. 14 Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms References Bennett, W.F. (ed). 1993. Nutrient Deficiencies Ulrich, A., J.T. Moraghan, and E.D. Whitney. and Toxicities in Crop Plants. St. Paul, MN. 1993. Sugar beet. In Nutrient Deficiencies APS Press. 202 p. and Toxicities in Crop Plants. St. Paul, MN. APS Press. 202 p. Engel, R.E., P.L. Bruckner, and J. Eckhoff. 1998. Critical tissue concentration and Voss, R.D. 1993. Corn. In Nutrient Deficiencies chloride requirements for wheat. Soil Sci. and Toxicities in Crop Plants. St. Paul, Soc. Am. J. 62:401-405. MN. APS Press. 202 p. Engel, R, L.J. Bruebaker, and T.J. Ornberg. Wichman, D. 2001. Fertilizer use on dryland 2001. A chloride deficient leaf spot of perennial forages. Fertilizer Fact #27. WB881 Durum. Soil Sci. Soc. Am. J. 65: Bozeman, MT. Montana State University 1448-1454. Extension Service. Gerendas, J., J.C. Polacco, S.K. Freyermuth, Wiese, M.V. 1993. Wheat and other small grains. and B. Sattelmacher. 1999. Significance of In Nutrient Deficiencies and Toxicities in nickel for plant growth and metabolism. J. Crop Plants. St. Paul, MN. APS Press. 202 p. Plant Nutr. Soil Sci. 162 (3): 241-256. Grewal, H.S. and R. Williams. 1999. Alfalfa genotypes differ in their ability to tolerate APPENDIX zinc deficiency. Plant Soil. 214:39-48. Grundon, N.J. 1987. Hungry crops: A Bo o ks guide to nutrient deficiencies in field crops. Brisbane, Australia: Queensland Nutrient Deficiencies and Toxicities in Crop Government. 246 p. Plants. W.F. Bennett, ed. 1993. St. Paul, MN. American Phytopathological Society (APS) Havlin, J.L., J.D. Beaton, S.L. Tisdale, and W.L. Press. 202 p. Approximately $69. Nelson. 1999. Soil Fertility and Fertilizers, 6th Edition. Upper Saddle River, N.J. Plant Nutrition Manual. J. Benton Jones, Jr. Prentice-Hall, Inc. 499 p. 1998. Boca Raton, FL. CRC Press. 149 p. Approximately $60. Jacobsen, J.S. and C.D. Jasper. 1991. Diagnosis of Nutrient Deficiencies in Alfalfa and Soil Fertility and Fertilizers, 6th Edition. J.L. Wheat. EB 43, February 1991. Bozeman, Havlin et al. 1999. Upper Saddle River, NJ. MT. Montana State University Extension. Prentice Hall. 499 p. Approximately $100. Jones, Jr., J.B. 1998. Plant Nutrition Manual. Boca Raton, FL. CRC Press. 149 p. Ex t e n s i o n Ma t e r i a l s Diagnosis of Nutrient Deficiencies in Alfalfa Mengel, K. and E.A. Kirkby. 2001. Principles of and Wheat, EB 43, February 1991. J.S. Plant Nutrition. Netherlands. Kluwer Jacobsen and C.D. Jasper. Bozeman, MT: Academic Publishers. 849 p. Montana State University Extension. Paterson, J. 2002. The need for copper and Approximately $7. zinc supplementation in Montana. In Excellent publication that includes a key Beef: Questions and Answers, Vol. 8, # 3. to plant-nutrient deficiency symptoms, Bozeman, MT. Montana State University photographs of deficient plants, and Extension. additional information on individual Solberg, E., I. Evans, and D. Penny (prepared nutrients, such as conditions favoring by). 1999. Copper Deficiency: Diagnosis deficiency, factors causing pseudo deficiency, and Correction. Agdex 532-3, September. and excess symptoms. Retrieved April 7, 2003 from Alberta Agriculture, Food, and Rural Development web site: http://www.agric.gov.ab.ca/ agdex/500/532-3.html. Module 9 • Plant Nutrient Functions and Deficiency and Toxicity Symptoms 15 Nutrient Management Modules (1-15) We b Re s o u r c e s Available and can be obtained http://aces.nmsu.edu/pubs/_a/a-123. Acknowledgments online or at the address below (add html We would like to extend $1 for shipping). our utmost appreciation to the Plant analysis sampling guidelines All are online in PDF format in and table of specific plant parts to following volunteer reviewers the category of ag and natural be tested for various crops. Source: who provided their time and resources, at http://www. New Mexico State University insight in making this a better msuextension.org/publications.asp Extension Service. document:

Order Extension materials from: http://www.agmin.com.au/Nutrient & Grant Jackson, Western Deficiency Guide Files/Deficiency Triangle Agricultural MSU Extension Publications Symptoms in Crops.htm P.O. Box 172040 Research Center, Conrad, An extensive list of nutrient Montana Bozeman, MT 59717-2040 deficiency symptoms in specific crops including barley, corn, Clark Schmidt, CCA, Billings, See Web Resources for online oats, and wheat. Also lists specific Montana ordering information. nutrients associated with each Alan Telck, CCA, Sheridan, deficiency symptom. Wyoming Pe r s o n n e l Engel, Rick. Associate Professor. http://www.back-to-basics.net/nds/ Mal Westcott, Western Montana State University, index.htm Agricultural Research Bozeman. (406) 994-5295. engel@ A good website featuring Center, Corvallis, Montana montana.edu photographs of all nutrient deficiencies in various crops. Jackson, Grant. Professor. Western Triangle Agricultural Research http://www.hbci.com/~wenonah/min- http://www.msuextension.org/ Center, Conrad. (406) 278-7707. def/list.htm publications.asp [email protected] Website featuring photographs of Montana State University Extension Publications ordering Jones, Clain. Extension Soil nutrient deficiencies in numerous information for printed materials. Fertility Specialist. Montana State crops. University, Bozeman. (406) 994- http://muextension.missouri. http://landresources.montana.edu/ 6076. [email protected] edu/explorepdf/agguides/pests/ FertilizerFacts/ Westcott, Mal. Professor. Western IPM1016.pdf Fertilizer Facts summarizing Agricultural Research Center, Complete publication covering fertilizer findings and Corvallis. (406) 961-3025. nutrient deficiency and toxicity recommendations based on field [email protected] symptoms; includes photographs research conducted in Montana of nutrient deficiencies in various by Montana State University Wichman, Dave. Superintendent/ crops. Source: University of personnel. Research Agronomist. Central Missouri Extension Service. Agricultural Research Center, Moccasin, (406) 423-5421 [email protected]

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