Cauliflower (Brassica oleracea var. botrytis)
Downy mildew (Perenospora parasitica)
Symptoms
- It is a disease characterized by yellowish to purplish patches on the leaves.
- The disease is very serious in nursery and it can also appear in the main field.
- High humidity, fog, drizzling rains, and heavy dew favour the disease development and spread.
- The first symptom observed are small, light green-yellow lesions on the upper leaf surface, later showing on the undersurface.
- The spots turn yellow or orange as they enlarge.
- During periods of high humidity, a grayish white moldy growth is developed on the undersurface of the leaf.
- Later the leaf may become papery and die.
Management
- All weeds serving as collateral host of the fungus should be removed and destroyed.
- Crop rotation with non-cruciferous plants.
- Use disease free seeds.
- Heat treatment of seeds at 43 – 50oC for 20 minutes.
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 | Copper hydroxide 77 WP | HiDice, Kocide 101 | Blue | 1g | 10 g | 200 g | 500 g | - |
| 2 | Potassium phosphonate 40 SC | Akomin | Green | 4ml/ litre of water | 40 ml | 800 ml | 2000 ml | - |
| 3 | Copper oxychloride 50 WP | Bensaan, Blitox, Blue copper, Bluetrox, Copter, Cupramar, Cuprina, Dhanucop, Fytolan, Fytox, Fytran, Fytolan, Hilcopper, Killex copper, Maincop Dhanucop, Star cop, Tagcop, Trucop | Blue | 2g | 20 g | 400 g | 1000 g | - |
Extremely Toxic
Highly Toxic
Moderately Toxic
