Foliar Ca  sprays:

The recommendation to prevent fruit disorders is to apply calcium chloride (CaCl2) at intervals during the growing season.  The application of 4.0 to 14.0 lb of actual Ca per acre per season in six to eight cover sprays. Minor alterations in the timing and rates of application usually have no effect on the results as long as the total amount is not changed.  The benefits of the treatments are reduced as the amount of Ca is reduced.  The amount applied would depend on the leaf and soil analysis, orchard history, and field observations. 
Disadvantages to the application of CaCl2  include the possibility of phytotoxicity, especially on the leaves, and the corrosiveness on the application equipment.  To overcome these disadvantages, many growers use a variety of commercial CaCl2 substitutes, but are these alternatives as effective and as cheap as CaCl2?
Table 2  and accompanied materials have been copied from the Pennsylvania Tree Fruit Production Guide (to access the table on the web, click on Table 15 in http://www.cas.psu.edu/docs/CASDEPT/Hort/TFPG/part1/part12p.htm). It is a list of some Ca materials with label rates per acre per application, per acre per season, and per acre per year.  Study this table carefully to compare the amount of Ca supplied by the different materials.   If the material you use is not in this list, the following step by step process will help you arrive at the same information.  Use this information to determine how much actual Ca the material you are using contains and how much it is  costing you.

Determining the amount of elemental calcium in a commercially formulated product. 

  1. Look for, or determine, the percentage of elemental calcium in the product. This should be listed somewhere on the label.
  1. For a liquid formulation, multiply the percentage (as a decimal) by the weight of the material per gallon. For a solid, multiply the percentage by the weight of material you will add to the tank. The result equals the pounds of calcium per gallon pound of formulated product.
  2. Determine the rate of formulated material you intend to apply per acre per application. For a specific calcium  product this is usually listed on the label.
  3. Multiply the amount of material per acre by the number of applications to be made during the season. Result equals the amount of total product per acre per season.
  4. Multiply the amount of total product per acre per season (from Step 4) by the pounds of calcium per gallon or pound of formulated product (from Step 2). The result equals the total amount of elemental calcium per acre per season.
  5. Compare the result from Step 5 with our recommendation of 4 to 14 pounds of elemental calcium per acre per season.
  6. Compare the season-long cost of materials. Multiply the amount of material used per season times the cost of the material.
  7. Compare the cost of elemental Ca.

Example 1. Product A sells for $6.50 per gallon and is a liquid containing 15% elemental calcium. The weight per gallon is 12 pounds. The label recommends 2 to 4 quarts per acre per application with eight applications suggested per season. You decide to apply 2 quarts per acre per application.

       Step 1:  Product contains 15% elemental calcium.
       Step 2:  12 lb x 0.15 = 1.8 lb of elemental calcium per gal.
       Step 3:  You choose to apply 2 quarts (or 0.5 gal) per acre per application.
       Step 4:  0.5 gal per acre per application x 8 applications per season = 4 gal of material per acre per season.
       Step 5:  4 gal x 1.8 = 7.2 Ca /acre /pre season
       Step 6: Our recommendation is 4.0 to 14.0 lb of elemental calcium per acre per season.
       Step 7:  4.0 gal x $6.50 per gal = $26.00 per season
       Step 8: $26.00 per season / 7.2  lb of elemental calcium per acre per season = $3.61 elemental calcium per acre
      Example 2.  Product B sells for $1.50 per pound and is a solid powder containing 30 percent elemental calcium.  The label recommends 3 to 4 pounds per acre per application with eight applications suggested per season.
       Step 1:  Product contains 30% elemental calcium.
       Step 2:  1 lb x 0.30 = 0.30 lb of elemental calcium per lb of material.
       Step 3:  You choose to apply 3.0 lb of material per acre per application.
       Step 4:  3 lb per acre per application x 8 applications per season = 24 lb of material per acre per season.
       Step 5:  24 lb x 0.30 = 7.2 lb of elemental calcium per acre per season.
       Step 6: Our recommendation is 4.0 to 14.0 lb of elemental calcium per acre per season.
       Step 7:  24 lb x $1.50 per lb = $36.00.
       Step 8:   $36.00 /7.2 lb of elemental calcium per acre per season = $5.00 elemental calcium per acre.

Determining the amount of product needed to apply 14 pounds of elemental calcium:

You are comparing two products to determine what rate you need to apply to achieve 14 pounds of elemental calcium per acre per season. Again use the same two materials outlined above and assume that you will be making eight applications during the season.

   1.  Divide the number of pounds of elemental calcium desired per season by the number of applications. The result is the pounds of elemental calcium needed per acre per application.
   2.  Divide the amount of elemental calcium per gallon or pound of material by the pounds of elemental calcium needed per acre per application. Result is the gallons or pounds of formulated material needed per acre per spray.
Example
Step 1: 14.0 lb of elemental calcium per acre per season ÷ 8 applications per     season = 1.75 lb
Step 2: Product A = 1.75 ÷ 1.8 lb elemental calcium per gal = 0.97 gal per           application
Product B = 1.75 ÷ 0.3 lb elemental calcium per lb = 5.83 lb per application

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