Spices and Condiments

Pests and diseases

Pests
Shoot borer (Conogethes punctiferalis)

• As in ginger, the shoot borer is an important pest of turmeric.
  
• The larvae bore into the pseudostems and feed on the growing shoots resulting in yellowing and drying of the infested shoots.
  
• The presence of bore holes in the pseudostem through which frass is extruded and the withered central shoot (dead heart) are characteristic symptoms of pest infestation.
  
• Spraying Monocrotophos (0.075%), or Dimethoate (0.1%) or Quinalphos (0.025%) during July-October at monthly intervals controls the pest.
  
• Hexameris sp., hymenopteran parasitoids have been identified as bio-control agents for this pest.
Leaf roller (Udaspes folus)

• The pest is abundant in the field during August-October. Spraying Carbaryl (0.1%), Dimethoate or Phosphamidon (0.05% each) can control the pest.
Rhizome scale (Aspidiella hartii)

• The pest infests the crop both in the field and in storage. In the field, the plants wither and dry during severe infestation.
  
• In storage, the shrivelling of the buds and rhizomes is observed due to pest attack.
  
• Dipping the seed rhizomes of turmeric in Quinalphos (0.025%) or Fenitrothion (0.05%) for 5 minutes after harvest and before planting/ storage + spraying of Phosphomedon (0.05%) in the field controls the pest.
• The larvae of the crane fly (Libnotes punctipennis) and rhizome fly (Calobata albimana) have been reported to bore into the rhizomes.

Nematodes
Nematodes (Meloidogyne incognita)

• The affected plants show stunted growth, yellowing, marginal and tip drying of leaves, reduced tillering and galling, and rotting of the roots.
  
• A high population of M. incognita causes yellowing and severe stunting and withering in large patches.
  
• The plants die prematurely leaving a poor crop stand at harvest. The infested rhizomes lose their bright yellow colour.
Radopholus similes

• The infested plants show a tendency to aging and dry faster than healthy plants.
  
• The infested rhizomes are a yolk-yellow colour compared with the golden-yellow colour of the healthy rhizomes and have shallow, water-soaked, brownish areas on the surface.
  
• The roots show rotting and most of the decayed roots are devoid of the cortex and stylar portions.
  
• The application of Thimet @ 10-15 kg/ha or Phorate 10 kg/ha at the time of field prepration or Aldicarb and Carbofuran (1-3 kg a.Vha) 3 weeks after planting controls the nematode infestation.
  
• The varieties Kodour and Chayapasupu are resistant to root-knot nematodes.
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The other species of nematodes reported to cause damage to this crop are Longidorous elongatus, Xiphinema elongatum, Hoplolaimus seinhorstii, Helicotylenchus multicinctus, Tylenchorhychus martini, Pratylenchus delattrei and Rotylenchulus reniformis.


Diseases
Leaf blotch

• This disease is caused by Taphrina maculans. The disease starts as small, scattered, oily-looking, translucent spots on the lower leaves when the plants are in the 3-to-4-leaf stage. The leaf-spots later turn dirty yellow and deepen to the colour of gold and sometimes to a hay shade.
• The adjacent individual leaf-spots of 1-2 mm in diameter coalesce forming reddish-brown blotches and lead to varying degrees of leaf blight.
• Foliar sprays with Dithane Z-78 (0.2%) or Dithane M¬45 (0.25%) at 15-day intervals controls the disease.
Leaf-spot

• This is caused by Collectotrichum capsici. The infection is usually confined to the leaf-blades and occasionally extends to the leaf sheath.
  
• The disease appears as elliptic to oblong spots of variable size on both surfaces, but more on the upper surface.
  
• These spots gradually enlarge in size and coalesce to cover the entire leaf area or form large necrotic patches.
  
• The spots vary from 4-5 cm in length and 2-3 cm in breadth.
  
• A fully-developed spot has a grayish-white centre with a brown margin surrounded by a yellowish colour in the shape of a defined halo.
  
• In severe infections, the leaves dry up and defoliate. Spraying of Bordeaux mixture (1%) or Dithane M-45 (0.25%) controls the disease.
Rhizome-rot

• This disease is caused by Pythium graminicolum and Pythium aphanidermatum.
  
• This is an important disease, prevalent in all turmeric-growing areas. The disease appears in patches in the field.
  
• The leaves of the infected plants become yellow and exhibit gradual drying along the margins.
  
• Water-soaked lesions develop on the pseudostem and become soft to the touch.
  
• The root system is adversely affected, as the roots rot completely.
  
• As the disease progresses, the infection gradually spreads.
  
• The infected rhizomes turn brown in colour.
  
• In the case of a severe attack, the yield is reduced considerably.
  
• Planting healthy rhizomes and seed treatment with Dithane M-45 (0.25%) + Carbendazim (0.1%) for 60 minutes and drying under the shade for 24 hours before sowing/storage are the recommended control measures.
  
• The seed rhizomes should be dipped in Blitox 50 (0.3%) before storage or sprayed with Carbendazim or Bordeaux mixture at the first apperance of the disease symptoms to control the disease.
  
• Trichoderma harziarum, Trichoderma hamatum or Trichoderma viride can be used as bio-control agents for this disease.
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