DISEASES

DISEASES & PESTS

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.
Turnip Yellow Mosaic Virus:
  • 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.
PESTS

Flea 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.

10.2

  • 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
Minimum distance (meter)
Foundation Certified
Fields of the other varieties 1600
 1000
Fields of the same variety not conforming to varietal purity 1600
 1000

b. Specific Requirements
Factor
Maximum permitted (per cent)
Foundation Certified
Off-type 0.10
 0.20
Other crop plants --
 --
Objectionable weed plants --
 --
Diseased plants 0.1
 0.50

B. Seed Standards
Factor
Standards for each class
Foundation Certified
Pure seed (minimum) % 98.0
 98.0
Inert matter (maximum) % 2.0
 2.0
Other crop seeds (maximum) Number/ kg 0.05
 0.10
Total weed seeds (maximum) Number/ kg 0.10
 0.20
Objectionable weed seeds (maximum) Number/ kg --
 --
Germination (minimum) % 70
 70
Moisture (maximum) % 6.0
 8.0


Last modified: Tuesday, 19 June 2012, 5:48 PM