Orchard Spray Rates
How to Determine the Amount of
Pesticide and Water to Use in Your Orchard

Bulletin 892-01

Calculations for Concentrate Applications,
How much pesticide is needed for a concentrate application?

Method 5: Use a pesticide rate customized to your fruit operation by the tree-row volume method and the percentage-of-standard method.

First, divide your dilute volume of water per acre by the standard dilute volume of water per acre, which gives you the percentage of standard for your trees. How to determine your dilute volume per acre was detailed on pages 4-6. The standard dilute volume for apples is 400 gallons per acre as defined on pages 1, 3, and 10.

your dilute volume of water per acre standard dilute volume of water per acre = the percentage of standard for your trees

For example, if you determined that it takes 180 gallons per acre for a dilute application to your apple trees, then your percentage of standard = 180 gallons per acre, divided by 400 gallons per acre = 45%. Your trees are 45% of standard.

180 gal. water per acre 400 gal. water per acre

=

0.45 Your trees are 45% of standard.

An alternate way to get the percentage of standard is to use tree size and spacing in the chart on page 19. For example, for trees 12 feet wide and 10 feet tall at 20-foot row spacing, the trees are 46% of standard if well-pruned, as found in the column for minimum dilute volume, or 65% of standard if unpruned, as found in the column for maximum dilute volume.

Second, determine the amount of pesticide to use by multiplying your percentage of standard by the full rate per acre. Remember that the full rate per acre = amount of pesticide per 100 gallons times 400 gallons water per acre of apples, as explained previously in Method 2 (page 10).

your percentage of standard x the full pesticide rate per acre = the amount of pesticide to use per acre

For example, if your trees are 45% of standard and you need to apply Imidan 70WP, which has a dilute rate of 1 pound per 100 gallons, then the full rate by the standard conversion is 1 pound per 100 gallons, times 400 gallons per acre, which equals 4 pounds per acre. Take 45% of the full rate: 45% of 4 pounds per acre is 0.45 times 4 equals 1.8 pounds per acre.

The full rate by the standard conversion:

1 pound 100 gal. water

x

400 gal. water acre

=

4 pounds Imidan per acre

45% of the full rate:

45% of 4 pounds per acre = 0.45 x 4 = 1.8 pounds Imidan per acre

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