- -  AGRICULTURE CORE CURRICULUM - -


(CLF6000) Advanced Core Cluster: ORNAMENTAL HORTICULTURE

 (CLF6350)  Unit Title: ELEMENTS NECESSARY FOR PLANT GROWTH

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 (CLF6357)  Topic: SYMPTOMS OF NUTRIENT     Time     Taught in Year(s) 
                     DEFICIENCIES             1 hour         3 and 4   
                     (N,P,K,Fe,S,Mg,B,Zn)
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        Topic Objectives: Upon completion of this lesson the student will 
        be able to:

        Learning Outcome #:

          (H-9) - List symptoms of plant nutrient deficiencies when the 
                    following minerals are inadequate: N,P,K,Fe,S,Mg,B, 
                    and Zn.

        Special Materials and Equipment: Colored pictures of plants with 
                    various deficiencies and/or fresh or dried samples of 
                    plants with deficiencies; copies of commercial soil
                    test reports

        References: Agrios, George N. (1978). PLANT PATHOLOGY (2nd ed.).
                      NY: Academic Press. 
                    WESTERN FERTILIZER HANDBOOK (7th ed.). (1985). 
                      Danville, IL: Interstate Printers and Publishers.

        Evaluation: Quiz by instructor


TOPIC PRESENTATION: SYMPTOMS OF DEFICIENCIES

A. When essential elements are present in the plant in amounts smaller than 
   minimum levels required for plant growth, the plant exhibits various 
   external and internal symptoms.

   1. These symptoms may appear on any or all organs of the plant 
       including leaves, stems, roots, flowers, fruit, and seeds. 

   2. A knowledge of these symptoms will help the student determine their 
       cause and aid in finding the cure.

B. Symptoms of nitrogen deficiency in plants include: 

   1. slow and, stunted growth, 

   2. parts that are light green to yellow in color (chlorotic), and

   3. "firing" of tips and center position of leaves beginning with the
       older leaves. 

C. Phosphorus deficiency symptoms include:

   1. slow and stunted growth,

   2. purplish coloration on foliage of some plants (this may be 
       associated or confused with cool or cold temperatures),

   3. dark green coloration with tips of leaves dying, 

   4. delayed maturity, and

   5. poor grain, fruit, or seed development.

D. Symptoms of potassium deficiency in plants include:

   1. tip and marginal leaf chlorosis and then death starting on more
       mature leaves, 

   2. weak stalks, plants "lodge" easily, 

   3. small fruit or shriveled seeds, and

   4. thin shoots and in, severe cases, dieback.

E. Symptoms of iron deficiency in plants include:

   1. interveinal chlorosis (yellowing) of young leaves (veins remain 
       green except in severe cases).

   2. twig dieback, 

   3. part of or entire leaf may dry, 

   4. leaf shedding, and, 

   5. in severe cases, death of entire limbs or plants.

F. Sulfur deficiency symptoms include: 

   1. young leaves light green to yellowish in color, symptoms resemble
       those of nitrogen deficiency, 

   2. small and spindly plants, and

   3. retarded growth rate and delayed maturity. 

G. Magnesium deficiency symptoms include: 

   1. interveinal chlorosis (yellowing) in older leaves, 

   2. occational appearance of necrotic spots,

   3. curling of leaves upward along margins, 

   4. occasional leaf-drop,

   5. "Christmas tree" area along midrib of leaf in the case of citrus.

H. Symptoms of boron deficiency in plants include: 

   1. death of terminal growth, witches'-broom causing lateral buds to
       develop and produce a effect;

   2. thickened, curled, wilted, and chloritic leaves; 

   3. cracks on surface and rot in center of fruit or tubers, and 

   4. reduced flowering or improper pollination.

I. Symptoms of zinc deficiency in plants include: 

   1. decrease in stem length and rosetting of terminal leaves, 

   2. leaves may be mottled or show interveinal chlorosis, 

   3. reduced fruit bud formation, 

   4. leaves are shed progressively from base to tip, and

   5. causes "little leaf" of apples, stone fruits, grapes and walnuts.

J. Note that although it has not been considered an "essential element" in 
   the past, there have also been molybdenum (Mo) deficiencies observed in 
   California fields of alfalfa and melons.

         __________________________________________________________
         ACTIVITY: 
                     
         1. Have students study colored pictures and preserved or
             fresh samples of deficient plants and determine the 
             deficient element.
         __________________________________________________________


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Note: It is difficult for a beginning student to make determinations
      of deficient elements by symptoms, since they will often vary 
      with the species affected and by the degree of deficiency. 
      The student, can, however, develop an appreciation of this important
      specialty through experience.

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12/27/90 PJK/sg

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