Leaf spot of turmeric is the most important disease of turmeric. It has become as major constraint in successful cultivation of turmeric. The disease has resulted in drastic reduction in rhizome yield.
Oblong brown spots with grey centres are found on leaves. Severely affected leaves dry and wilt. The disease is usually appears in October and November.
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Proper spacing should be maintained (for single row planting: 45cm between rows and 15cm among plants and 4cm depth and Broad ridge system or paired row system under drip irrigation the farmers follow broad ridge system of planting in which 120 cm broad ridge are formed and two rows of rhizomes planted at a spacing of 15 x 45 x 45 x 15 cm and 4 cm depth.
Select seed material from disease free areas. Infected and dried leaves should be collected and burnt. Crop rotations should be followed whenever possible and far as possible use only rhizomes from known sources .
Cultivate resistant/tolerant varieties. Proper spacing should be maintained. Pseudomonas fluorescens and Trichoderma harzianum can reduce the disease when the disease pressure is low.
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Leaf extract of Ashoka (Polyanthia longifolia) and bulb extract of onion (Allium cepa) can be reduce the disease
Treat seed material with mancozeb at 3gm/litre of water or carbendazim at 1 gm/litre of water, for 30 minutes and shade dry before sowing.
Spray mancozeb at 2.5 gm/litre of water or carbendazim at 1gm/litre; 2-3 sprays at fortnightly intervals.
Spraying Blitox or Blue copper at 3 gm/lt of water was found effective against leaf spot.
Rhizome treatment with carbendazim and mancozeb (0.1 per cent) and and foliar application of propiconazole (0.1 per cent) at 45 and 90 days after planting (DAP) can help reduce the disease.
(Dr. Utpal Dey, Department of Plant Pathology, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani, Maharashtra, email: utpaldey86@gmail.com, Mobile: 8275824103.)