Turmeric
Leaf Blotch of Turmeric
Taphrina maculans
Fungus
In a Nutshell
- Several small, oval, irregular spots appear on both surfaces of the leaves.
- The spots coalesce and form irregular lesions.
- Plants show a scorched appearance and rhizome yield is reduced.
Can also be found in
Turmeric
Symptoms
The disease typically appears on the lower sides of leaves. The individual spots are small with 1 - 2 mm in width and are mostly rectangular. The spots are arranged in rows along the veins and coalesce freely to form irregular lesions. First, they appear as pale yellow discolourations and later become dirty yellow. Infected leaves are distorted and have a reddish-brown appearance. In severe cases, the plants present a scorched appearance and the rhizome yield is reduced.
Recommendations
Organic Control
Products containing Pseudomonas fluorescens and Trichoderma harzianum can reduce the infestation when the disease pressure is low. A leaf extract of Ashoka (Polyanthia longifolia) or hommade extract of onion bulbs can also reduce the infestation.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments, if available. Treat the seed material with Mancozeb @ 3 g/liter of water or Carbendazim @ 1 g/liter of water for 30 minutes and shade dry before sowing.
What caused it?
The fungus is mainly airborne and the primary infection occurs on lower leaves. The inoculum survives in dried leaves of hosts that are leftover in the field. Secondary infection is caused by ascospores that spread from successively maturing asci and infect fresh leaves. In summer, the pathogen persists through ascogenous cells on leaf debris and desiccated ascospores and blastospores in soils and among fallen leaves. The disease is favoured by high soil moisture, 25°C temperature and leaf wetness.
Preventive Measures
- Practice proper sanitation.
- Collect and burn infected and dry leaves to reduce inoculum source in the field.
- Select seed material from disease-free areas.
- Practice crop rotation where possible.
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