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How to Manage Pests

UC Pest Management Guidelines

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Citrus

Fruit Thinning with Naphthalene Acetic Acid (NAA)

(Reviewed 9/08, updated 9/08)

In this Guideline:
Variety Amount to Use Time
  Calculate impact of pesticide on air quality
A. ORANGES, TANGERINES (MANDARINS), 100–500 mg/liter When fruitlets are 3/16–3/4 inch
  TANGELOS and TANGORS (100–500 ppm) (5–20 mm) diameter
 
  COMMENTS: Restricted entry interval (REI): 24 hours. Make only 1 application per year. Within the specified concentration range, inadequate to excessive thinning may occur. In general, inadequate thinning occurs from the lowest label rate when maximum daytime temperatures on the day of application and several days thereafter are relatively low (~85°F [29°C]). Excessive thinning generally occurs from the highest label rate when maximum daytime temperatures on the day of application and several days thereafter are relatively high (~100°F [38°C]). In addition, excessive thinning can occur when NAA is applied to unhealthy or water-stressed trees. Do not use on varieties where both young fruit and fruit close to maturity are present on the tree. Do not apply within 150 days of harvest. Use either the ammonium salt or the potassium salt formulation of NAA.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
Plant Growth Regulators
C. J. Lovatt, Botany and Plant Sciences, UC Riverside
Acknowledgment for contributions to Plant Growth Regulators:
C. W. Coggins, Jr., Botany and Plant Sciences, UC Riverside

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