Method 2: Use the full rate per acre as calculated by the standard conversion from the dilute rate.
When a pesticide label states the rate as an amount of pesticide per 100 gallons of water, but you want to make a concentrate application and you need to know the equivalent amount of pesticide per acre, then you can make the standard conversion to the full rate per acre. The full rate is sometimes referred to as the concentrate rate. This full rate per acre should be thought of as the maximum amount of pesticide to use per acre.
Make the standard conversion by multiplying the amount of pesticide per 100 gallons times the standard dilute volume of water per acre. In the case of apples, the standard dilute volume per acre is usually defined as 400 gallons per acre. The amount of pesticide per 100 gallons, times 400 gallons per acre, gives you the full amount of pesticide needed per acre of apples. This is based on the old assumption, as mentioned near the beginning of this bulletin, that it takes 400 gallons of spray mix for a thorough dilute application to an acre of large apple trees.
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For example, if the dilute rate for Captan 50WP on apples is 1.5 pounds per 100 gallons of water, then the full rate per acre is 1.5 pounds per 100 gallons, times 400 gallons water per acre, which equals 6 pounds Captan per acre.
| 1.5 pounds 100 gal. water |
x | 400 gal. water acre |
= | 6 lbs. Captan acre |
Note: It is these full rates per acre calculated by the standard conversion that we list in the column called "rate per acre" in our Ohio tree fruit spray guide. Again, this full rate per acre should be thought of as the maximum amount of pesticide to use per acre.
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Advantage of Method 2: It is relatively easy to calculate, and the calculations have already been done and are listed in our Ohio tree fruit spray guide.
Disadvantage of Method 2: It can result in using higher than necessary rates, especially for small trees.
Recommendation: Do not use this method if you want the most economical rate; it is better to use Method 1 or 4 or 5.
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