AMVAC · 1-Naphthaleneacetic Acid, Potassium Salt 24.2% · EPA Reg 5481-628 · Plant Growth Regulator
Document last checked 2026-05-30
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Mandolin is a plant growth regulator used for thinning citrus crops. Its active ingredient is 1-Naphthaleneacetic Acid, Potassium Salt (24.2%), which is equivalent to 20.2% 1-Naphthaleneacetic Acid (NAA) per gallon. The product is designed to thin fruit during a heavy crop year to provide adequate return bloom in the following season. It can be applied to mandarins (tangerines, tangelos, and clementines) and oranges. Application rates vary based on the target concentration of NAA (ppm) and the spray volume used (150, 200, 250, or 300 gallons per acre). For mandarins, the product is applied to the entire fruiting area during the early stage of development (5 to 20 mm in diameter) during the normal 'June Drop' period. For oranges, it is applied during the early stage of development (5 to 20 mm in diameter) during the normal 'June drop' in Florida. Users should note that higher thinning activity may occur during hot and dry conditions, particularly when temperatures exceed 85°F. When handling, use long-sleeved shirts, long pants, shoes plus socks, chemical-resistant gloves, and protective eyewear. Avoid contact with skin and eyes, as it causes moderate irritation. Always follow local extension specialist advice for specific timing and application methods, especially regarding wind speed and spray drift management.
Pests covered (1)
Scale Insects
Areas treatable (1)
Citrus (Mandarins and Oranges)
How to treat each type of area 1
Citrus (Mandarins and Oranges)
| Location |
Rate |
Unit |
Dilution |
Label notes |
| Outdoor |
Varies by concentration |
fl. oz./acre |
150-300 GPA |
Used for fruit thinning during heavy crop years to ensure adequate return bloom. |
Mixing instructions 2
| For pests |
Amount |
Per |
Finished strength |
Label notes |
| Mandarins |
17.5-52.6 |
fl. oz./acre |
200-300 ppm NAA |
Spray volumes of 150, 200, 250, or 300 GPA. |
| Oranges |
6-24 |
fl. oz./100 gallons |
100-500 ppm NAA |
Apply at 100 to 500 ppm. |
Worker safety
Re-entry interval (REI)
48
PPE required
Long-sleeved shirt and long pants, shoes plus socks, chemical-resistant gloves (except for pilots), and protective eyewear.
Timing & weather
- Apply during early stage of development (5 to 20 mm diameter) during 'June Drop'.
- Avoid application when wind speeds are greater than 10 mph.
- Higher thinning activity may occur during hot/dry conditions (above 85°F).
Use restrictions 5
- Do not apply within 90 days of harvest (PHI 90 days).
- Do not exceed 52.6 fl. oz. (0.75 pounds AI equivalent) per acre per treatment or per year.
- Do not apply more than one application per year (for mandarins).
- Do not use in a greenhouse.
- Do not apply this product through any type of irrigation system.
Active ingredient
1-Naphthaleneacetic Acid, Potassium Salt 24.2%
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