Management of karnalbunt, aquarantine disease, in wheat

Karnal Bunt disease of wheat caused by Tilletia indica is a designated disease and a limiting factor in wheat export because most countries regulate the Karnal Bunt (KB) pathogen as a quarantine pest. KB pathogen is seed, soil and air borne. The seed must be threshed and examined for KB infection. Therefore, the post harvest management of KB in wheat seed production through mechanical processing is very important. Pre-cleaner and screen grader removed 83.1 and 61.4% of total KB infected seed present in the seed lot and reduced KB infection from 1.42 to 0.24% and 4.27 to 1.65% in 2012–13 and 2013–14, respectively. Hence, a total of 18 combinations, comprising of three deck slopes (S₁-2⁰, S₂-2.5⁰, S₃-3⁰), three feedings (F₁-5Kg, F₂-10Kg, F₃-15Kg per minute) and two output settings (O₁-45cm deck width, O₂-43cm deck width) of specific gravity separator were studied with an objective of getting maximum Karnal bunt free seed per unit of time. Minimum KB infection in final product (0.04 and 0.28%), maximum final output (12.58 and 12.78Kg/minute) and KB free seed recovery per minute (12.58 and 12.75Kg) with 84.1 and 86.4% recovery efficiency has been obtained by the treatment S₁F₃O₁ (slope of deck 2⁰, feeding 15Kg/minute, output deck width 45cm) in 2012–13 and 2013–14, respectively. Mechanical processing reduced KB infection by more than 93%, depending on the intensity of infection, and increased seed quality i.e. seed germination improved by 7.71% and physical purity by 2.41%.