Karnal bunt of wheat

Karnal bunt of wheat

Pathogen:- Tilletia barclayana.

Systemic position of pathogen:- class- basidomycetes; order-ustilaginales; family- tilletiaceae.

Distribution :- In India , for the first  time this diseases was reported from karnal and since then this disease has been named as  ‘karnal bunt of wheat’. In Uttar Pradesh, this disease was first reported in 1942 and since then it has been reported from several districts of western utter Pradesh. Elsewhere in the country this disease is unknown. Through the disease, is of less importance, yet in certain years it caused heavy damage.

Symptoms:- This disease can be observed in the field only when the ears are emerged out, and grains are formed in an affected plant, not all the ears are infected. On the other hand, in an infected ear, only a few grains not more than five or six, are being infected and changed into sori. The sori are always irregularly distributed on the infected ear. On the maturity of the grain, the other glumes in a spike spread out, and the bunted grains may be observed. The bunt-balls remain covered by the pericarap in the beginning, but later on they burst and the spore-mass is exposed .The spore-mass smells strongly of rotten fish like other two bunts.

The pathogen:- the karnal bunt of wheat is caused by Tilletia barclayana .The spores are spherical, smooth-walled and measuring 22- 49 micron id diameter. Prior to germination, the spores requires a long resting period, on germination the spores produces a short, stout basidium. The sporidia are produced in large numbers (60-120) at apex of the basidium. The primary sporida are needle-shaped and flexible. The secondary sporidia, if produced are sickle-shaped.

Nature and recurrence of disease:- the disease is spoil-borne as well as air-borne. The spores found in the soil germinate, forming a large number of needle-shaped sporidia , and sickle-shaped secondary sporidia. The sporidia are being carried to the inflorescence through the air currents, where they infect the ovaries and the developing kernels. Infection takes place only when the flowering occurs.

Control measure:-

Crop rotation- This method of control may be helpful to some extent.

Resistant varieties- for effective and economical control, the resistant varieties should be grown. Some important resistant varieties are: kalyan sona, S 227, PV 18, HD 2012, 4513, 4519, IWP 72,87,127, HB 383, UP 2002, etc.