What Is Captan?
Captan (C9H8Cl3NO2S) is a pesticide classified as a fungicide, used to protect crops from the harmful effects of fungi and bacteria. It is known for its broad-spectrum action, inhibiting multiple points of action, unlike fungicides that target specific processes such as mycelial respiration or cell wall synthesis.
It falls under the M (multiple action point contact activity) group in pesticide classification, based on its mechanism of action. Its diverse inhibitory effects prevent mycelium growth, reducing the likelihood of resistance development in fungi.
Captan is an odorless, white powdery substance at room temperature and pressure, often dissolved in water for application.
Uses of Captan
As a versatile fungicide, Captan is used for prevention and treatment in various agricultural settings. Its applications span two major categories:
1. Application by Spraying on Crops
By diluting captan-based fungicides in water, they can be sprayed onto crops at various growth stages. Its efficacy against fungicide-resistant strains makes it suitable for a broad range of plants, including fruit trees (apples, pears, grapes, peaches, plums), vegetables (eggplants, cucurbits), and ornamentals (roses). It is notably effective against downy mildew in cucumbers and gray mold in greenhouse tomatoes and strawberries, with some crops safe for spray application up to the day before harvest.
2. Seed Treatment
Another method involves treating seeds with captan fungicides, typically at a rate of 0.2% to 0.4% fungicide by seed weight. This protects the seeds from surface and internal pathogens, ensuring stable germination. It is effective against seedling blight in solanaceous plants (tomatoes, eggplants, peppers), cucurbits (cucumbers, melons, watermelons, pumpkins), and diseases caused by Pythium and Rhizoctonia in corn and other vegetables.
Types of Captan
Captan fungicides are categorized by their active ingredient concentration:
1. Orthocide Hydrate 80
Containing 80.0% captan, orthocide hydrate 80 is approved for a wide array of crops and diseases, including vegetable blights, fruit tree diseases, and seed treatment for cucurbits, eggplant, and ginger. It is also effective as a soil irrigation treatment during the seedling stage.
2. Oxirane Hydrate
With 20.0% captan and an additional 30.0% copper 8-hydroxyquinoline, oxirane hydrate combats a range of diseases in vegetables and fruit trees and is notable for its dual-active formula offering broad-spectrum prevention.
3. Caprate Hydrate
Caprate hydrate, which contains 60.0% Captan and 10.0% benomyl, targets diseases in pears, eggplants, and tomatoes. It is distinguished by its preventative and curative properties and long-lasting effectiveness.
Other Information on Captan
Precautions for Use
- Wear gloves, masks, and protective eyewear during application to prevent contact with eyes, nose, and skin.
- Adhere to established daily intake limits to avoid excessive consumption.
- Exercise caution to prevent adverse effects on silkworms, honeybees, and beneficial organisms, especially in environments where they are present.