Onion (Allium cepa L.)
White rot (Sclerotium rolfsii, S. cepivorum)
Symptoms
- The initial symptom of the disease is yellowing and dieback of leaf tips. Stem, stem plate and roots get destroyed.
- The bulbs become soft and water soaked.
- White fluffy or cottony growths of mycelium with abundant black sclerotia resembling mustard grain are seen on the infected bulbs.
Management
- Repeated cultivation of onions on the same piece of land should be avoided.
- Crop rotation with cereal crops is recommended.
- Use of disease free areas.
- Hot water treatment of bulbs at 49 °C.
- Solarization of soil at high temperature i.e. 35 °C for 18 hours or 45 °C for 6 hours reduces the disease incidence by 50-70%.
- Heavy manuring with organic manures reduces the disease in the crop.
- Application of bio-control agents like Trichoderma viride to the soil reduces the disease inoculum.
Chemical Control
| Sl.No | Generic Name | Trade Name | Color code | Dosage/litre | Knapsack Sprayer (Capacity 10L) | Recommendation | Remarks | |
|---|---|---|---|---|---|---|---|---|
| Dosage/acre (200 L) | Dosage/hectare (500 L) | |||||||
| 1 | Mancozeb 75 WP | Devidayal M-45, Dhanuka M 45, Dhanuka M-45, Dithane, Dithane M-45, Hilthane, Hindustan M 45, Indofil M 45, Izeb M-45 Manzate, Luzen-45, Macoban, Macoban M-45, Mancosaan, Mancosaan M-45, Maneb Manzane, M-Guard, Savour M 45, Tata M-45 Eurofil-NT, Uthane M-45, Veera, Zinthane | Green | 4 g/ litre of water/kg of seed | - | - | - | Seed treatment |
| 2 | Thiram 75 WS | Hexathir, Tagithram, Thiram 75 DS, Thiride, Vegfru Thiram | Blue | 4 gm/kg of seed | - | - | - | Seed treatment |
| 3 | Mancozeb 75 WP | Devidayal M-45, Dhanuka M 45, Dhanuka M-45, Dithane, Dithane M-45, Hilthane, Hindustan M 45, Indofil M 45, Izeb M-45 Manzate, Luzen-45, Macoban, Macoban M-45, Mancosaan, Mancosaan M-45, Maneb Manzane, M-Guard, Savour M 45, Tata M-45 Eurofil-NT, Uthane M-45, Veera, Zinthane | Green | 3 g/ litre of water | 30 g | 600 g | 1500 g | - |
Extremely Toxic
Highly Toxic
Moderately Toxic
