- Crop rotation with other cros that are not attacked by the purple blotch fungi.
- Control of onion thrips may reduce disease infection.
- Avoid wet season specially when sed production is done.
- Avoid close planting and practce the recommmeneded spacing.
- Do not apply excessive Nitrogen.
- Use recommended fungicides.Protective application of fungicide is recommended when conditions are fevourble for dieases infection. Common fungicides are effective but repeated application is needed when conditions are favorable for the disease.
Sunday, July 8, 2012
Control of purple blotch of onion
Purple blotch of Onion
This is a fungal disease distributed in many countries and it can attack other crops like shallots, leeks, garlic and chives.
Disease is severe during wet and warm weather condotion.
Causal organism: Alternaria porri
Symtoms and damage
At the initial stage small water soaked lessions appear on the leaves and flower stalks.These lesions turn in to brown color with reddish purple margins and enlarged .Later these leaves will die.Older leaves are more susceptible for the disease.When thrips damage is present onion plants are more easily attacked by the purple blotch fungi.During harvet fungi can infect onion bulbs and bulb rot can occur during storage.