Phosalone: A Broad-Spectrum Organophosphate Insecticide and Acaricide

Technical Introduction

Phosalone (chemical name: O,O-diethyl-O-[6-chloro-2-oxo-3-benzoxazolinyl] phosphorodithioate) is a broad-spectrum organophosphate insecticide and acaricide widely used in agriculture. It was developed in the 1960s and is known for its effectiveness against a wide range of insect pests and mites.

Its mode of action is typical of organophosphates:

• Inhibits acetylcholinesterase (AChE), an essential enzyme in the nervous system of insects.

• This causes accumulation of acetylcholine, leading to paralysis and eventual death of the pest.

Phosalone exhibits both contact and stomach action, with some residual activity on plant surfaces.

Applications

• Agricultural Crops:

  • Widely used on cotton, fruits (apple, citrus, pear), vegetables, and cereals.

  • Controls chewing and sucking pests such as aphids, leafhoppers, thrips, caterpillars, beetles, and fruit borers.

  • Effective against mites (acaricidal action), making it dual-purpose.

• Ornamentals:

  • Used in ornamental plant protection against mites and insect infestations.

• Stored Products (in some regions):

  • Applied for control of stored grain pests, though less common compared to fumigants.

• Veterinary / Public Health (limited):

  • Occasionally applied in ectoparasite control on animals, but mostly replaced by safer alternatives.

Advantages

• Broad Spectrum: Effective against both insects and mites.

• Dual Mode of Action: Contact and stomach poison, ensuring multiple routes of effectiveness.

• Residual Activity: Provides long-lasting control compared to highly volatile OPs like dichlorvos.

• Versatile Use: Applicable to field crops, orchards, vegetables, and ornamentals.

• Cost-Effective: Relatively low production cost compared to newer insecticides.

Specifications (Typical Parameters)

FAQ

Q1: What crops benefit most from Phosalone?
A: It is widely applied on cotton, citrus, apple, pear, vegetable crops, and cereals, especially where both insect and mite infestations occur.

Q2: Is Phosalone systemic?
A: No, Phosalone is not systemic. It acts as a contact and stomach poison, with residual activity on treated surfaces.

Q3: How does it compare to other OP insecticides like Malathion or Chlorpyrifos?

• Malathion: Safer but less potent, mainly for household and mosquito control.

• Chlorpyrifos: Stronger residual soil insecticide, used for termites and root pests.

• Phosalone: Balanced insect + mite control, primarily used in orchards and crops.

Q4: What precautions are required in handling?
A: As a moderately toxic organophosphate, applicators must wear PPE, avoid inhalation, and wash thoroughly after use. It should not be applied near water bodies due to fish toxicity.

Q5: Is Phosalone still registered worldwide?
A: Phosalone is restricted or banned in many countries due to environmental and toxicological concerns, but still used in some regions for crop protection where regulatory approval remains.