- -   AGRICULTURE CORE CURRICULUM  - -


(CLF7000)  Advanced Core Cluster:  PLANT AND SOIL SCIENCE

  (CLF7600)   Unit Title:  PRUNING

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  (CLF7601)   Topic:  PURPOSES OF          Time      Taught in Year(s) 
                      PRUNING             1 hour          3 and 4       
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         Topic Objectives:  Upon completion of this lesson the student will 
         be able to:

         Learning Outcome #:

           (K-1)  -  Discuss why pruning is necessary in crop production.

           (K-11) -  Explain the purposes of pruning fruit trees.

         Special Materials and Equipment: 

         References: Mika, A.  (1986).  PHYSIOLOGICAL RESPONSES OF FRUIT 
                       TREES TO PRUNING.  Horticulture Reviews.  8: 339-378.

         Evaluation: Quiz by instructor

TOPIC PRESENTATION:  PURPOSES OF PRUNING

A.  When a plant's form is modified by pruning its functions are influenced.

    1.  Pruning is an essential practice wherever fruit is grown.

    2.  Pruning requires a specific knowledge of the species, variety and 
        strain of fruit being grown.

    3.  Pruning must be custom fit to the total of all other practices that 
        affect the plant.


B.  What is pruning?

    1.  Pruning  means removing certain parts of the plant in order to 
        modify and utilize its natural habits so that more and better fruit 
        can be obtained at less cost and over a longer period.

C.  The reasons that we prune include the following.

    1.  Pruning helps us secure a vigorous, mechanically strong, healthy 
        plant.

        a)  Removal of branches encourages growth of new spurs and other 
            bearing wood.

        b)  Removal of broken, diseased or insect infested parts keeps the 
            plant healthier.

    2.  Tree shape is determined and maintained by proper pruning practices.

        a)  This aids in economy of orchard operations.

        b)  It also can help in making harvesting and spraying easier.

    3.  Distribution of fruiting area over the entire tree is 
        maintained.

        a)  This will aid in gaining fruit size.

        b)  Color will be improved because of good exposure to light.

    4.  Longevity of the tree or vine will be increased.

        a.  This will guarantee a succession of profitable crops.

        b.  This, then, will also decrease costs.

D.  Other factors that also need to be considered include:

    1.  Species, strain or variety, 

    2.  age of the tree or vine,

    3.  past care, and 

    4.  the purpose for which the crop is being used, (canning or freezing,
        shipping, juice or wine, or drying).


E.  Effects of top pruning are:

    1.  A reduction in photosynthetic (leaf) surface area and therefore a 
        reduction in the total amount of carbohydrates available for growth.

    2.  An increase in the proportion of food reserves available to 
        the remaining growing points (buds) and fruits.

    3.  A decrease in total leaf transpiration resulting in conservation of
        soil moisture; thus allowing the tree to survive larger where water 
        is limited.

    4.  Root growth is decreased because of less food being manufactured.

7/25/90 sg
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