DISEASES & PESTS
DISEASES & PESTS
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Diseases
1. Early blight : (Alternaria solani)
- The infection appears on lower leaves with necrotic spots having concentric rings.
- This fungus survives in the soil in diseased plant debris.
- High moisture and low temperature is favourable for disease.
Control measures
- Follow crop rotation.
- Spray the crop with mancozeb@ 0.2 per cent, 30-35 days after planting and grow tolerant varieties such as Kufri Jeevan.
2. Late Blight : (Phytophthora infestans)
- The infection appears at the tips or edges of the lower leaves with circular or irregular water soaked spots.
- White downy fungus growth appears on the underside of the leaves around the spots.
- Cloudy weather is conducive for very fast spread of the disease.
- Later the disease may spread to tubers and initiate rotting.
Control measures
- Plant only healthy disease free seed tubers.
- Spray the crop with mancozeb @ 0.25 per cent well in advance.
- Avoid applying excess irrigation and nitrogen.
3. Black Leg / Soft Rot : (Erwinia spp.)
- The bases of shoots develop a blackened shrivelled cortex and its growth is stunted.
- Leaflets become reddish in colour at the tips.
- Branches become stiffened and more upright than normal.
- The affected haulms are jet black in colour at the soil level.
- The tubers become watery and upon rotting give off offensive sulphurous odour.
Control measures
- Obtain healthy tubers for planting.
- Collect and destroy affected plants.
- Wash the tubers with chlorinated water before storage and avoid planting too early.
4. Wart disease of potato: (Synchytrium endobioticum)
- Affected plants show warty growth protuberances on stems, stolons and tubers.
- The roots are not affected.
- The wart consists of distorted, proliferated, branched structures grown together into a mass of hypertrophied tissue.
- It is difficult to control once it has been established in a field.
Control measures
- Obtain disease free seed for planting.
- Soil treatment with 5 per cent Formalin is also effective.
Pests
1. Cut worms: (Agrotis spp)
- They feed only at night and cut the sprouts at ground level.
- They also attack tubers and make holes thereby reducing market prices.
Control measures
- Drench the plants with chlorpyriphos (0.04 %) where the damage is noticed.
- Use only well rotten Farm Yard Manure.
2. Leaf eating caterpillars : (Spilosoma obliqua, Spodoptera exigua)
- The caterpillars of both the species cause damage by feeding on potato leaves.
Control measures
- Spray the crop with deltamethrin (0.0025%).
3. Aphids : (Myzus persicae)
- Aphids suck the sap from leaves.
- Affected plants become weak, leaves become yellow and curl downwards.
- Aphid secretes honeydew, which gives rise to sooty mould and other fungal diseases.
Control measures
- Spray malathion (0.05%) or oxy-demeton methyl (0.025%).
4. Potato tuber moth: (Phthorimaea operculella)
- It is major pest of potato in storage.
- It can also attack in the field.
- It bores and makes tunnel into the potato tubers.
Control measures:
- Sow healthy insect free potato tubers.
- Use only well rotten Farm Yard Manure.
- Do earthing up carefully, so that the tubers are not exposed in the field to ovipositing female moths.
- Spray the crop with carbaryl (0.1 %).
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Last modified: Sunday, 17 June 2012, 6:37 AM