Radish (Raphanus sativus)
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.
- 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.
- Radish heads develop sunken black spots and rots.
Management
- All weeds serving as collateral host of the fungus should be removed and destroyed.
- Spray Copper oxychloride 50 WP (2 gram/litre of water) or Copper hydroxide 77 WP (1 gram/litre of water) or Potassium phosphonate 40 SC (3-4 ml/litre of water).
- Rotate the crop excluding the members of Brassica family
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 | Potassium phosphonate 40 SC | Akomin | Green | 4 ml/ litre of water | 40 ml | 800 ml | 2000 ml | - |
| 2 | Copper hydroxide 77 WP | HiDice, Kocide 101 | Blue | 2 g/ litre of water | 20 g | 400 g | 1000 g | - |
Extremely Toxic
Highly Toxic
Moderately Toxic
