Tikka disease of groundnut

It explains in detail about the tikka disease of groundnut. Causal agent, mesures to control it is also mentioned.

1. Tikka Disease of Groundnut Keshav Narayan Pai Msc I DOS in Botany

2. Content Introduction Causal Organism Symptoms Disease Cycle. Favourable Condition. Disease Management Conclusion Reference

3. Introduction Groundnut is the most important oilseed crop of India. The Total area under ground nut is about 8 million hectares . Tikka disease is the major disease of groundnut in India. It occurs in every state in India and in every ground of nutgrowing countries of the world. In Uttar Pradesh, the disease is locally known as chitwa or haldai .

4. Causal organism The causal organism for the tikka disease of ground nut are Cercospora personata and Cercospora arachidicola . The Symptoms caused by the two pathogens will differ. This disease is also called Leaf spot of Ground nut because it causes leaf spots on the leaves .

5. Symptoms appear when the plants are 1or 2 months old. Due to excessive spotting on the leaves, there is gradual weakening of the foliage which results in defoliation. Consequently, fewer and smaller nuts are formed . According to Sundarram (1965) severe intensity of infection leads upto 22%reduction in yield. Symptoms

6. Symptoms According to Woodruff(1933) designated the disease caused by C.arachidicola as early spot and that caused by C.personata as late spot. The first symptom of both the leaf spots is the appearance of pale areas on the upper surface of older leaves. As the lesions develop the two species can be distinguished.

7. Early Leaf Spot Symptoms Sub-circular dark brown spots are produced on the upper leaflet surface. The spots are of lighter shade of brown on the lower side of the leaflets. Yellow halo is seen around the brown spots.

8. spot on stem

9. Infected leaf

10. Late leaf spots are nearly circular and darker than early leaf spots. Yellow halo develops around each only in later stage of development. Late leaf spots can be distinguished from those of early leaf spots. Late leaf spots are darker with no or light yellow halo. Late leaf spot symptoms Late leaf spot

11. Causal organism The mycelium of C.arachidicola is inter and intracellular, brown,septate and without haustoria . Conidophores are yellowish brown and as the conidium remains attached to geniculation on conidiophore . Conidiophores are 22-44 micron long and 3-5 micron broad continuous or 1-2 septate .

12. Causal organism Cercospora personata produces an intercellular branched mycelium. To absorb food from the host tissue, haustoria are developed. Lesions appears 2-4 weeks later. Conidiophores of C. personata are 25-54 micron long, 5-8 micron broad continuous or 1-2 septate . Conidia are terminal and each conidiophores bear each single conidium at the apex. It is potentially more damaging because it produces more spots, spreads faster and causes earlier defoliation

13. Disease Cycle Perennation The disease perpetuates through conidia lying in the soil on diseased plant debris and through conidia being carried in the shell of groundnut. Primary Infection When the new crop of groundnut starts growing, the viable conidia are brought to the host surface by various agencies, germinate in favourable conditions and cause primary infection.

14. Cont..... Secondary infection The secondary infection on healthy plants in the same field or adjacent fields is brought by conidia produced on primary infected leaves. The conidia are dispersed by air or other agencies , which bring them on the healthy leaves. Later they germinate in favourable conditions and cause infection.

15. Relative humidity is the most important factor for infection. A period of three days of high humidity is essential for maximum infection . Prolonged low temperature and dew also favour severe infection. Favourable factors

16. The application of potash slightly decreases disease incidence. Leaf spot development is minimal when gypsum is applied as a source of calcium. Unfavourable Condition

17. As the disease is soil-borne, proper crop rotation is important. Plant disease debris should be burnt to avoid soil borne inoculum . Early planting,alternation in date of sowing and use of maturing varities helps to escape rom the attack of the disease. Growing moderately resistant cultivars like ICGV 89104, ICGV 91114 (EM), ICGV 920920, ICGV 92093 (MM). Foliage spray with Bordeaux Mixture (4:4:50), Dithane M-45 (0.2%), Benlate and Bavistin (0.1%) gives good results. Disease Management

18. Disease Management Cultural Method Grow tolerant varieties can be grown wherever early leaf spot is severe. Intercropping pearl millet or sorghum with groundnut (1 : 3) is useful in reducing the intensity of early leaf spot. Crop rotation with non-host crops preferably cereals. Mechanical Method Deep burying of crop residues in the soil, and removal of volunteer groundnut plants are important measures to reduce the primary source of infection

19. Cont.. Biological Method Foliar application of aqueous neem leaf extract (2-5%) or 5% neem seed kernel extract at 2 weeks interval 3 times starting from 4 weeks after planting is good. Chemical Method Spray carbendazim 0.1% or mancozeb 0.2% or chlorothalonil 0.2%.

20. Conclusion Tikka Disease is a common disease in ground nut caused by Cercospora arachidicola and Cercospora personata . In the diseased condition, many circulars spots appear on the surface of the leaf . The conidia of the fungus present in soil or those present in the fruit shell is the source of infection. Use of fungicides controls the disease.

21. Mehrotra.R.S .(1980). Plant Pathology .Tata Mc.Graw Hill Pub.CO.Ltd . Pg.no-455-465. Rangaswamy,G and Mahadevan,A (2002). Diseases of crop plants in India ,Prentice Hall of india,Pvt.Ltd.Pg.no-334-343. www.flickr.pathology.Tikkadisease.Com Reference

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