crop cultivation

Bedding plants are afflict-ed by a number of nutri-ent deficiencies. Thereare three diagnostictests that can be used to

assess these deficiencies — soil test-ing, foliar analysis and visual diag-nosis. Soil testing and foliar analy-

sis should be practiced on a routineschedule to avert nutritional disor-ders; hopefully, one will not needto resort to visual diagnosis,because the presence of symptomsis evidence that a preventableproblem has occurred. Worse yet,not all symptoms may be reversible

when corrective action is taken.However, when nutritional errorsdo occur, visual diagnosis is a pow-erful tool for rapid identification ofthe problem and verification of soilor foliar test results.

When using visual diagnosis,one must first account for all other

factors that could cause similarsymptoms. A number of nutrition-al disorder symptoms also can bethe symptoms of other causalagents, such as air pollution, pesti-cide damage, herbicides in or nearthe crop area, plant growth regula-tors and pathogenic diseases, par-

Grower 101:

By Paul Nelson, Brian Whipker, John Dole, Dharmalingam Pitchay,James Gibson, Amy Rhodes and Brenda Cleveland

Phosphorus deficiency in mimulus. The deficient plant in the middle has passed the stage of deepergreen foliage and now has chlorosis on lower leaves, while the plant on the right has progressed on tonecrosis of lower foliage.

Potassium deficiency in salvia. The plant is smaller, foliage is darker and necrosis has formed on lowerfoliage margins.

Diagnosing Bedding Plant

Nutrient DeficienciesThe different nutrient deficiencies in bedding plants exhibit a range of symptoms.Learn the common symptoms of a number of deficiencies, such as nitrogen, copper, boron and more, to aid in diagnosis.

This nitrogen-deficient sunflower with chlorosis on lower leaves isbeginning to give way to necrosis. (Photos: NCSU Floriculture Group)

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crop cultivation

ticularly viruses and environmen-tal extremes such as frost, desicca-tion or temperature extremes. Avaluable asset for sorting out theseother causal agents is a crop pro-duction record. Further help can befound in production and pest con-trol manuals for the crop at hand.

Diagnosing SymptomsWhen it is evident that the

symptoms are those of a nutritionalproblem, the diagnostic approachbecomes important. Where are thesymptoms on the plant? Symptomsof mobile nutrient deficiencies,including nitrogen, phosphorus,potassium and magnesium, appearin older tissue at the base of theplant. Symptoms of non-mobilenutrient deficiencies — includingcalcium, iron, manganese, zinc,copper and boron — generallyappear first at the top of the plant inyoung tissue. Symptoms of thesemi-mobile nutrient sulfur appearacross the whole plant, in this case,as a uniform chlorosis of all leaves.

Is distorted growth of young tis-sue an early symptom? This wouldimplicate calcium or boron deficien-cy. Is unusually deep-green foliagecoupled with heavy stunting anearly symptom? This points tophosphorus deficiency. Commonsymptoms for each deficiency aregiven in the next section.

Typical Nutrient Deficiency Symptoms

Nitrogen deficiency. Plantsbecome noticeably smaller, leavesmay be more upright and the plantas a whole may become lightgreen. The oldest leaves will be themost chlorotic, and this chlorosisspreads uniformly across theseleaves. After considerable time,older leaves become necrotic anddrop off if abscission is possible forthe species in question. Red to pur-ple-red discoloration may developin petioles, stems and leaves inmany species including begonia,celosia, marigold, ornamental kale,pansy, salvia and snapdragon.

Phosphorus deficiency. Theplant becomes severely stunted,and at the same time, the foliagebecomes deeper green than normal.In some species, the older leavesdevelop purple coloration. Thenolder leaves develop chlorosis fol-lowed by necrosis. In young plants,necrosis may occur along withchlorosis or without prior chlorosis.Roots grow longer than normal butare fewer in number when the defi-ciency is moderate.

Potassium deficiency. Themargins of older leaves becomenecrotic. Chlorosis may briefly pre-cede this necrosis. Alternatively,necrotic spots may form across theblades of older leaves but moretoward the margin. Soon the olderleaves become totally necrotic.Seedlings and young beddingplants, prior to the formation ofchlorosis and necrosis on olderfoliage, are more compact anddeeper green than normal.

Calcium deficiency. Symptomsare expressed at the top of the plant.

Young leaves may develop variablepatterns of chlorosis and distortionsuch as dwarfing, strap-like shapeor crinkling. The edges of immatureleaves become necrotic; this is oftenthe first noticeable symptom.Shoots stop growing. Petals orflower stems may collapse. Theedges of poinsettia bracts mayburn. Roots are short, thickenedand noticeably branched.

Magnesium deficiency. Olderleaves develop interveinal chloro-sis. Often, chlorosis will start alongthe terminal margins of leaves andthen move inward between veins,forming an interveinal pattern. Inseedlings of several species, chloro-sis may begin in leaves at the midor slightly lower region of theplant. In several species, pink, redor purple pigmentation will devel-op in the older leaves following theonset of chlorosis.

Sulfur deficiency. Foliage overthe entire plant becomes chlorotic,with chlorosis on any given leafbeing quite uniformly distributed. �

Top: Calcium deficiency in petunia. Young tissue becomes distorted and necrotic with amodest amount of chlorosis. Bottom: Magnesium deficiency in begonia expressed asinterveinal chlorosis in mature leaves.

Top: Sulfur deficiency in bracteantha expressed as uniform chlorosis over the entire plant.Bottom: Iron deficiency in petunia. A progression can be seen in leaves where interveinalchlorosis is giving way to total loss of pigment, as seen in the white leaves, and finally to necrosis.

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Symptoms tend to be more pro-nounced toward the top of the plantin some species or at the base of theplant in very few species. Whilesymptoms on the individual leaflook like those of nitrogen deficien-cy, it is easy to distinguish sulfurdeficiency from nitrogen deficiencybecause the latter begins in the low-est leaves rather than over thewhole plant.

Iron deficiency. Young leavesbecome chlorotic. Chlorosis canstart in an interveinal or uniformpattern in young leaves but moreoften ends up interveinal. In latestages, the leaf blade may lose allpigment, passing through stages ofincreasingly lighter green to clearyellow and finally white. Necrosisoccurs at the yellow or white stages.

Manganese deficiency. Youngleaves become chlorotic. As in irondeficiency, chlorosis may be generalacross the leaf blade or interveinal.In young plants, chlorosis mayaffect the entire plant but will be alittle more pronounced in the youngleaves. In advanced deficiency, tannecrotic spots form in the chloroticareas between the veins.

Zinc deficiency. One or moreof various symptoms develop onyoung leaves. These include a lit-tle chlorosis in varying patternsbut tend toward interveinal,abnormally small leaves; shortinternodes that give the stem arosette appearance; and distortionof leaves in the forms of leaf curl,rolling of margins and spoonshapes. Following the young leafsymptoms, seedlings developnecrosis often on older, immatureor recently mature leaves. Inkalanchoe, zinc deficiency canexpress itself as a fasciation (a flat-tened, highly branched stem).

Copper deficiency. Pigmentacross the plant becomes darker, giv-ing it a blackish- or bluish-green hue.Young and recently mature leavescommonly curl along their lengths orat the terminal end. A modestamount of chlorosis may or may notdevelop in young leaves, and it maybe uniform or tend toward inter-veinal. Tips and lobes of these leavesmay retain green pigment longer thanthe rest of the leaf. Necrosis suddenlyappears on recently mature leavesand spreads rapidly, often resembling

desiccation. Petioles and stems associ-ated with recently mature leaves ofsnapdragon may also become necrot-ic and collapse.

Boron deficiency. Flower symp-toms can include incomplete forma-tion of flower parts, such as fewerpetals; small petals; sudden wiltingor collapse of petals; notches of tis-sue missing in flower stems, leafpetioles or stems; collapse of flowerstems; and abortion. Death of theflower bud gives rise to branching,which is followed by death of thenew buds, eventually leading to aproliferation of shoots termed a“witch’s broom.” Vegetative tissuesymptoms can include short intern-odes; crinkling of young leaves;corking of young leaves, stems andbuds; thickening of young leaves;and chlorosis of young leaves, butnot in any definite pattern. Rootsbecome short and thick with even-tual death of root tips.

Molybdenum deficiency. As faras we know, molybdenum deficien-cy has not been a problem with bed-ding plants. Poinsettia is the onlygreenhouse floral crop it is known

to effect. The margins of leaves atthe middle of poinsettia plantsbecome chlorotic, presenting a sil-houette appearance, and thenquickly necrotic. Symptoms spreadup and down the plant. Theseleaves may also become misshaped,resembling a half-moon patternwith some crinkling.

Paul Nelson, Brian Whipker, JohnDole are from North Carolina StateUniversity; Dharmalingam Pitchayis from Rakers and Sons Inc.;James Gibson is from West FloridaResearch and Education Center,University of Florida; Amy Rhodesis from Wicomico County ExtensionOffice; and Brenda Cleveland isfrom North Carolina Dept. Agricul-ture & Consumer Services. ContactNelson at paul_nelson@ncsu.edu or (919) 515-1191.

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LearnMoreFor more information related to this article, go to www.gpnmag.com/lm.cfm/gp120607

Top: Manganese deficiency in pansy. Chlorosis of young leaves tending toward an interveinalpattern followed by tan necrosis. Bottom: Zinc deficiency in zinnia seen as chlorosis of young leavesfollowed by rapid necrosis of recently mature leaves.

Top: Boron deficiency in begonia. Young tissue is distorted, internodes are short, buds areaborting, plant is highly branched and roots are short. Bottom: Copper deficiency in NewGuinea impatiens manifested as interveinal chlorosis and marginal rolling in young leavesfollowed by sudden and rapid necrosis in recently mature leaves.

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