DISEASES
DISEASES & PESTS
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Powdery Mildew: (Erysiphe cruciferarum)
- Affected plants show powdery patches of varying size on leaves.
- Dry atmosphere is favourable for development of this disease.
Control measures:
- Irrigate the crop regularly.
- Remove leaves as soon as disease appears and destroy them.
- Before observing symptoms, spray dinocap (0.05%) or wettable sulphur (0.2%) at 10-15days interval.
Downy Mildew: (Peronospora parasitica)
- Affected leaves show grayish white patches on under surface of leaves.
- Leaves turn yellow and later die.
Control measures:
- Remove affected leaves and destroy them.
- Spray Zineb @ 0.2 per cent.
Soft Rot: (Erwinia carotovora)
- Affected roots become soft from inside while outer skin remains hard and firm.
Control measures:
- Uproot affected plants along with roots and destroy.
Dry Rot:
- Affected roots show drying symptoms, and brown, sunken canker like areas develop on the roots.
Control measures:
- Avoid the attack of slugs and snails.
- These cause wounds on turnip which facilitate bacterial entry.
- Affected plants can be uprooted and destroyed.
- Affected plants do not grow properly, root development slows down and the quality deteriorates.
- The disease is transmitted by flea beetle.
Control measures:
- Remove affected plants, control flea beetle population and remove cabbage plants as they serve as collateral host of mosaic virus.
PESTSFlea Beetle: (Phyllotreta sp.)
- They make small holes in the leaves. Besides, they transmit Turnip Yellow Mosaic Virus.
Control measures:
- Hoeing may reduce population of this pest.
- Also spray carbaryl (0.1%) as soon as the attack is noticed.
Wire Worms:
- They bore roots and make tunnels.
Control measures:
- Regular cultivation will reduce the incidence.
Mustard Saw Fly: (Athalia promixa)
- It feeds on leaves and pods, and damages the seed.
- The affected leaves and fruits show holes.
Control measures:
- Mix follidol M (2%) or malathion dust (5%) @ 20-25 kg/ha in the soil at the time of soil preparation.
- Spray malathion (0.05%) or dichlorvos (0.04%) as soon as the attack is noticed.
- It is caused due to the deficiency of boron.
- The disorder is prevalent in very acidic soil where boron is deficient.
- The symptoms are characterized by the appearance of grey or brown colour in the inner portion of the affected roots.
- The roots become unfit for consumption.
Correction:
- Avoid the sowing in too acidic soils.
- Maintain adequate soil moisture to prevent drought condition.
- Incorporate borax @10-15kg /ha in the soil before sowing
- Spray the crop with boric acid (0.2%), 2-3 times at vegetative stage.
- Turnip bears hermaphrodite flowers even though it is highly cross-pollinated crop.
- Honey bees are main pollinators.
- Therefore, maintain 1600m and 1000m isolation distance for foundation and certified seeds, respectively between two different varieties and between the crops like rape, mustard, chinese cabbage and rutabaga.
- Raise seed crop either by seed to seed method or root to seed method.
- Seed crop is sown at wider distance of 45 cm apart on ridges.
- Sow seeds in the month of August to September.
- Apply 100 quintal of Farm Yard Manure during field preparation, 40kg of P at the time of transplanting the roots and 25kg of K before flowering per hectare.
- Application of 25kg of N in pre-bolting stage is beneficial.
- In the month of November, roots are uprooted, selected and foliage as well as top of roots are clipped (preferably 2/3rd tops and ½ of the roots) and are replanted at a distance of 45 x 45cm.
- Light irrigation is done just after replanting of roots.
- Rogue out all off-types and diseased plants.
- First roguing is done 20-30days after sowing, second when roots are lifted and replanted and third during flowering and pod formation stage.
- In higher hills, roots are uprooted by the end of October and replanting is done in the month of March-April. Initiation of seed stalks and flowering starts by the end of April depending upon variety, time of planting, area where seed production is being done.
- Harvesting is done in May end depending on the altitude of the seed production site preferably when 60-70per cent pods turn yellow brown.
- Delay in harvesting results in shattering of seeds.
- Harvesting, threshing and curing operations are like other cole crops.
- Thresh and winnow seeds and dry in sun and store in cloth bags under cool, dry and well-ventilated place.
- Turnip seeds remain viable for about 3-4 years under good storage conditions.
Seed Yield:
- 600-800kg/ha depending upon environmental factors and the varieties used.
A. Fields Standards
a. General requirements
Isolation
Seed fields should be isolated from the contaminants as shown in the table given below:
Contaminants
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Minimum distance (meter)
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Foundation
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Certified
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Fields of the other varieties
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1600
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1000
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Fields of the same variety not conforming to varietal purity
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1600
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1000
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b. Specific Requirements
Factor
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Maximum permitted (per cent)
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Foundation
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Certified
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Off-type
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0.10
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0.20
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Other crop plants
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--
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--
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Objectionable weed plants
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--
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--
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Diseased plants
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0.1
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0.50
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B. Seed Standards
Factor
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Standards for each class
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Foundation
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Certified
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Pure seed (minimum) %
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98.0
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98.0
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Inert matter (maximum) %
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2.0
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2.0
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Other crop seeds (maximum) Number/ kg
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0.05
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0.10
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Total weed seeds (maximum) Number/ kg
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0.10
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0.20
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Objectionable weed seeds (maximum) Number/ kg
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--
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--
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Germination (minimum) %
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70
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70
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Moisture (maximum) %
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6.0
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8.0
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Last modified: Tuesday, 19 June 2012, 5:48 PM