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

Bulletin 892-01

Calculations for Dilute Applications,
How much pesticide is needed for a dilute application?

The amount of pesticide to use per acre is the dilute rate times the dilute volume. The dilute rate is the amount of pesticide per 100 gallons of water. The dilute volume is either the full standard (maximum) of 400 gallons per acre, or a customized amount that is likely to be much smaller (100­200 gallons per acre) as described earlier.

amount of product per acre = (dilute rate) x (dilute volume)   = amt. of pesticide 100 gal. x gallons of water acre

For example, two orchards of different-sized trees need a dilute application of Guthion 50WP, which is used at a dilute rate of 0.75 pound per 100 gallons.

In the orchard of large standard trees that requires 400 gallons to spray to the point of runoff, the amount of Guthion to use for a dilute spray is 0.75 pound Guthion per 100 gallons water, times 400 gallons water per acre, which equals 3.0 pounds Guthion per acre.

0.75 pounds 100 gal. water x 400 gal. water acre = 3.0 pounds Guthion acre

In the orchard of small trees that requires 120 gallons to spray to the point of runoff, the amount of Guthion to use for a dilute spray is 0.75 pound Guthion per 100 gallons water, times 120 gallons water per acre, which equals 0.9 pound Guthion per acre.

0.75 pound 100 gal. water x 120 gal. water acre = 0.9 pound Guthion acre

For another example with the same two orchards, how much superior oil per acre is needed at half-inch green if the dilute rate is 2 gallons of oil per 100 gallons of water?

For the large trees in this example:

2 gal. oil 100 gal. water x 400 gal. water acre = 8 gal. of oil acre

For the small trees:

2 gal. oil 100 gal. water x 120 gal. water acre = 2.4 gal. of oil acre

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