Introduction In Turmeric, leaf spot and leaf blotch are the most important diseases. They effect the crop in its fast growing period and causes yield losses upto 60%.

Top

The Common Diseases In Turmeric Disease Symptoms Control Rhizome and root rot (Phythium graminicolum ) Complete drying of leaves. In advanced stages rhizomes get decomposed and decayed Drench the soil with Mancozeb (2.5g/lit) solution. Leaf Blotch (Taphrina maculans) Small oval, rectangular or irregular brown spots on either side of leaves Spray Carbendazim (1g/lit) or Mancozeb (2.5g/lit) +1ml Sandovit for 3-4 times. Leaf spot (Colletotrichum capsici ) Brown spots with grey centres on leaves and surrounded by yellow holes. Severely effected leaves dry and wilt Spray Dithane M-45 @3 g/litre of water (or) Bavistin @ 1 g/litre of water.

Top

Leaf Spot Colletotrichum capsici Occurrence The disease is usually appears in August and September. It is also observed in November in certain areas. Epidemiology The disease occurs when there is continuous high humidity in the atmosphere. Symptoms Oblong brown spots with grey centres are found on leaves. The spots are about 4-5 cm in length and 2-3 cm in width. In advanced stages of disease black dots representing fungal acervuli occur in concentric rings on spot. The grey centres become thin and gets teared. Severely effected leaves dry and wilt. They are surrounded by yellow halos. Indefinite number of spots may be found on a single leaf and as the disease advances, spots enlarge and cover a major portion of leaf blade. The fungus produce toxic metabolites which cause necrosis on leaves. Necrosis was found with in 4 hours of treating excised turmeric leaves with toxin solution. Mode of spread The fungus is carried on the scales of rhizomes which are the source of primary infection during sowing. The secondary spread is by wind, water and other physical and biological agents. The same fungus is also reported to cause leaf-spot and fruit rot of chilli where it is transmitted through seed borne infections. If chilli is grown in nearby fields or used in crop rotation with turmeric, fungus perpetuates easily, building up inoculum potential for epiphytotic outbreaks. Control measures Seed material should be selected from disease free areas. Seed material should be treated with Dithane M –45 @ 3g/litre of water or Bavistin @ 1 g/litre of water. Seed material should be dipped for 30 minutes in the fungicidal solution and should be shade-dried before sowing. The disease is effectively controlled by spraying Dithane M-45 @ 2.5 g/litre of water or Bavistin 1g/litre , 2-3 sprayings should be given at fortnightly intervals The infected and dried leaves should be collected and burnt in order to reduce the inoculum source in the field. Spraying Blitox or Blue copper at 3 g/l of water was found effective against leaf spot. Crop rotations should be followed whenever possible. Cultivate tolerant varieties like suguna and sudarshan.

Top

Leaf Blotch Taphrina maculans Occurrence Leaf blotch disease of turmeric is widely distributed in India as well as in Japan. The organism is pathogenic on several other cultivated and wild species of Curcuma and Hedychium. Epidemiology This disease is usually appears in October and November. Relative humidity of 80% and temperatures of 21-23° C favours the primary infection. Secondary infection is related to the availability of large inoculum potential, periodically produced under cool and humid conditions. Symptoms This disease is usually appears on lower leaves in October and November. The individual spots are small 1-2 mm in width and are mostly rectangular in shape. The disease is charectarised by the appearance of several spots on both the surfaces of leaves, being generally numerous on the upper surface. They are arranged in rows along the veins. The spots coalesce freely and form irregular lesions. They first appear as pale yellow discolourations and then become dirty yellow in colour. The infected leaves disort and have reddish brown appearance. The disease hastens defoliation of leaves. Mode of spread The fungus is mainly air borne and primary infection occurs on lower leaves with the inoculum surviving in dried leaves of host, left over in the field. The ascospores discharged from successively maturing asci into 8 spored microcolonies and infect fresh leaves without dormancy, thus causing secondary infection. Secondary infection is most dangerous than primary one causing profuse sprouting all over the leaves. The fungus persists in summer by means of ascogenous cells on leaf debris, and dessicated ascospores and blastospores in soil and among fallen leaves Control measures Seed material should be selected from disease free areas. Seed material should be treated with Dithane M -45 @ 3g/litre of water or Bavistin @ 1 g/litre of water. Seed material should be dipped for 30 minutes in the fungicidal solution and should be shade-dried before sowing. The disease is effectively controlled by spraying Dithane M-45 @ 2.5 g/litre of water or Bavistin 1g/litre , 2-3 sprayings should be given at fortnightly intervals or Carbendazim (1g/lit) or Mancozeb (2.5g/lit) mixed wits 1ml Sandovit can be sprayed 2-3 times. The infected and dried leaves should be collected and burnt in order to reduce the inoculum source in the field. Spraying Blitox or blue copper at 3 g/l of water was found effective against leaf blotch. Crop rotations should be followed whenever possible.

Top

Rhizome Rot Phytium graminicolum Symptoms Starting from the margins the leaves get dried up, collar region of pseudostem becomes soft and water-soaked and plants collapse. The rhizomes decay as a result of the attack of the fungus. Control Seed Material should be selected from disease free areas. Avoid water Stagnation in the field. Light soil may be preferred and drainage facility to be ensured. Grow tolerant varieties like Suguna and Sudarshan. Crop rotation to be followed. Deep ploughing to be given in Summer. Planting to be done in Ridge and furrow method. Remove diseased plants and the soil around plants to be drenced with Mancozeb (3gm/lit) or 3gm Ridomil M.Z. Spray on the crop Mancozeb (2.5g/lit) or Carbendazim (1g/lit) +1ml Sandovit. Seed treatment is a must. Keep Rhizomes in 3gm Mancozeb or 1gm Carbendazim or 3gm Ridomil M.Z or 2.5 gm Metalaxyl mixed in one litre of water solution for one hour and shade dry before planting.

Top