KARNAL BUNT OF WHEAT

CAUSAL ORGANISM,SYMPTOM,MANAGEMENT

1. P PAT – 302 DISEASES OF FIELD CROPS AND THEIR MANAGEMENT (1+1) ASSIGNMENT TOPIC KARNAL BUNT OF WHEAT SUBMITTED BY, COURSE TEACHER DEEPTHI.S, Dr. PARTHASARATHY.S, 2015021027. Asst. Prof., PLANT PATHOLOGY

2. CAUSAL ORGANISM: Tilletia indica Mitra ( Telomorphic stage). Initially, the disease was reported as Neovassia indica ( Mitra ) Mundkur in 1940 then it was called as Tilletia indica Mitra in 1953.

3. NAME OF THE DISEASE International Common Names English :   Indian bunt of wheat; new bunt; partial bunt of wheat. French :   carie de Karnal . Local Common Names Germany :   Indischer Weizenbrand .

4. The disease is sometimes called partial bunt because only part of the kernel usually is affected. The infected grain gives decaying fish smell due to trimethylamine .

5. HISTORY The first report of a new bunt disease in wheat came from the region of Faizalabad (Pakistan) in 1909. This was presumably Karnal bunt, which was first formally recorded in 1930 near the north Indian city of Karnal ( Mitra , 1931). Within India the pathogen spread and can now be considered widespread in northern and central India.

6. SYSTEMATIC POSITION Domain : Eukaryota Kingdom : Fungi         Phylum: Basidiomycota             Subphylum: Ustilaginomycotina                 Class: Ustilaginomycetes                     Subclass: Exobasidiomycetidae                         Order: Tilletiales                             Family: Tilletiaceae                                 Genus: Tilletia                                     Species: Tilletia indica

7. MODE OF INFECTION Primary spread of disease– The leaves of monocotyledons appeared to support sporidial survival. Secondary spread of infection - Seed borne and soil borne disease.

8. FAVOURABLE CONDITIONS High humidity favours this disease. Temperature ranges from (8 - 23°C ) Frequent rainfall favours disease development. High dose of nitrogen. Close planting favours pathogen attack.

9. OCCURENCE IN WORLD Asia Africa North and South America Europe

10. OCCURRENCE IN INDIA Uttar Pradesh Haryana Punjab Himachal Pradesh Rajasthan and Madhya Pradesh.

11. SYMPTOMS The fungus causes a reduction in the length of ears as well as in the number of spikelets of bunted ears . Infected plants may be dwarfed . In general,  T. indica  rarely infects more than a few spikelets per ear and then the affected grains are not swollen.

12. Oblong or ovoid sori , 1-3 mm diameter, develop, containing dusty, brown to black spore masses. The smell of decaying fish on grains.  In advanced attack, tissues along the suture and adjacent endosperm are replaced by spores. Both glumes and grains may fall to the ground.

13. SYMPTOMS ©agritech.tnau.ac.in

14. SYMPTOMS ©agritech.tnau.ac.in

15. PATHOGEN CHARACTER Teliospores are dark reddish to coppery, dull brown or dark brown, some spores typically black/opaque, globose to subglobose . Occasionally with a mycelial fragment attached,24-47µm diameter exospore with thick, truncate, compact projections.

16. symptoms © agritech.tnau.ac.in

17. TELIOSPORE OF Tilletia indica © https:www.cals.ncsc.edu

18. ©https:www.cals.ncsc.edu

19. ECONOMIC IMPORTANCE The disease appeared in the Punjab (India) around 1930. It was epidemic there in 1953-1954. Until 1970, sporadic outbreaks occurred every 2-3 years in the Punjab, Haryana and Uttar Pradesh regions, with a disease incidence of 0.1-10%. Annual yield losses of about 0.2% .

20. In 1974 and 1975, the disease was epidemic in other regions (Himachal Pradesh, Tarai areas of Uttar Pradesh and the Gurudaspur area of the Punjab) with 50% infection on the cultivar HD-2000. In Mexico, where Karnal bunt appears regularly, direct losses are not very significant and do not exceed 1%.

21. LIFE CYCLE © agritech.tnau.ac.in

22. IDM : CULTURAL PRACTICES: Grow resistant varieties such as HD 1907, L 176, HI 358, HP 743 and L 191. Crop rotation may help to control the pathogen, because  T. indica  can survive for up to 4 years in the soil. The movement of farm machinery from contaminated fields may also be restricted.

23. To prevent the spread of  T. indica  into previously unaffected areas, the use of disease-free seed is essential. Deep ploughing is done to remove spores. Split application of Nitrogen fertilizer reduces the incidence of the disease.

24. CHEMICAL CONTROL Chemical seed treatments have proved to be ineffective in killing the teliospores of T. indica  on seeds of wheat, with the exception of mercurial compounds, which are banned in most countries. Bleach, in combination with heat treatment, is effective(Soaking at 35°C for 12 h was the most effective treatment).

25. Carboxin + thiram and Chlorothalonil have been used as seed treatments in the USA and Mexico. Foliar spray of Propiconazole was shown to be effective against natural infection in India. Apply Cyproconazole @ 500 ml/ha and Bavistin @ 1000g/ha may be recommended.

26. BIOLOGICAL CONTROL Leaf extract of Azadiracta indica and Cassia fistula used as spray. Seed treatment with Thiram or Carbendazim 2g/kg makes the seed free from seed borne pathogen. Foliar spray of conidial suspension of Trichoderma viridae or T. harzianum @ 5ml/ha.