DISEASES OF TURMERIC

DISEASES OF TURMERIC

1. RHIZOME ROT
The yield is considerably reduced due to the attack of this disease.

Symptoms:
  • The affected plants show progressive drying of the leaves, which proceeds first along the margins and later the entire leaf dries up.
  • The base of the aerial shoots shows water soaked soft lesions.
  • The root system is adversely affected and as the disease progresses, infection gradually passes to the rhizomes, which begin to rot and become soft.
  • The colour of the affected rhizomes is changed into different shades of brown.
Pathogen:
  • Different fungi like Pythium aphanidermatum (Edson) Fitzp., P. graminicolum Subram. and Fusarium solani (Mart.) Sacc. have been reported to be associated with this disease.
  • The pathogen is described in detail in ginger diseases.
Disease cycle and epidemiology:
  • These fungi are both seed and soil borne.
  • High temperature and soil moisture favour the disease development.
Management:

i. Select healthy seed rhizomes for sowing.
ii. Collect and destroy the infected clumps and burn them.
iii. Follow atleast three years crop rotation.
iv. Use tolerant cvs. like PCT-13, PCT-14, and Shillong.
v. Dip seed rhizomes in the solution of metalaxyl + mancozeb (0.25%) before sowing and with the initiation of the disease, drench the plants with the same chemical.

2. TAPHRINA LEAF BLOTCH
This disease was first described by Butler (1911) and now it has been observed in all the turmeric growing areas of the country. Severe outbreaks of this disease have been reported from Rayalaseema area of Andhra Pradesh.

Symptoms:
  • Several spots of the disease appear on both surfaces of leaves, being generally more numerous on the upper surface.
  • Spots of 1-2 mm in diameter, first appear as pale yellow discolouration not sharply defined from the rest of the tissue, become dirty yellow and then deepen to the colour of old gold and some times to bay shade.
  • The infected leaves are distorted, have a reddish brown appearance and become yellow much sooner in comparison to the normal ones.
Pathogen:
  • The disease is caused by Taphrina maculans Butler.
  • The fungus produces cuboid ascogenous cells several layers in depth in the subcuticular interspaces of the epidermis.
Disease cycle and epidemiology:
  • The fungus persists by means of ascogenous cells on the leaf debris and as desiccated ascospores and blastospores on the soil and amongst fallen leaves.
  • Ascospores cause primary infections.
  • Optimum temperature for infection is 21-23o C along with 80 per cent RH.
Management:
i) Collect and destroy the infected plant debris.
ii) Use resistant cvs. like CLL 324, Amalapuram, Mydukur, Karhadi local, CLL326, Ochira 24 and Alleppey.
iii) With the initiation of the disease, spray the crop with funcides like carbendazim (0.1%) or thiophanate methyl (0.1%) or mancozeb (0.25%) or propineb (0.25%) and repeat at 10-14 days interval.


3. LEAF SPOT
This disease was first reported from Coimbatore districts in Tamil Nadu and is now prevalent in all the turmeric growing tracts in India. The disease mostly appears during August and September when the humidity is high.

Symptoms:
  • The disease manifests in the form of elliptic or oblong spots of variable size.
  • In the initial stages, the spots remain small but very soon many of them increase in size.
  • Many spots coalesce and develop irregular patches often involving a major portion of the leaf which eventually dries up.
  • The centre of the spots is greyish white and thin with numerous black dot like acervuli on both surfaces.
  • There is an indefinite yellowish region outside the spot forming a halo around.
  • The infected field presents a scorched look during the years of epiphytotics.
Pathogen:
  • The disease is caused by Colletotrichum capsici (Syd.) Butler & Bisby.
  • The pathogen is described in detail in bell pepper and chili diseases lecture.
Disease cycle and epidemiology:
  • The pathogen may be carried over in the rhizomes as dormant stromata between the scales.
  • The disease appears when there is high and continuous humidity in the atmosphere.
Management:

i) Use healthy seed rhizomes.
ii) Use resistant cvs. like Nallkatla, Sugandham Duvvur and Ganikota.
iii) With the initiation of the disease, spray the crop with carbendazim (0.1%) and repeat at 15 days interval.
Last modified: Friday, 2 March 2012, 5:24 AM