06-08-2013, 04:53 PM
Management of Karnal Bunt Caused by Tillitia indica using Biocontrol Agents
ABSTRACT
Dwarf wheats though accelerated the production tremendously; stabilization of yield still remains one of the important problems. Wheat suffers from the ravages of several maladies afflicted by rusts, smuts, bunts, mildews and foliar blights. Factors like varietal reshuffle, intensive cultivation and high input technology are designated to be responsible for minor diseases to become major production constraint. One such disease that has caused much concern is Karnal bunt of wheat caused by Neovossia indica (Mitra) Mundkur. This disease was first reported from Karnal district of Haryana (India) in 1930s and was subsequently found in Pakistan, Afghanistan, Mexico and Nepal .This disease is widely prevalent in all the wheat growing areas in North-Western India. During severe epidemics total losses in India has been around 0.3 to 0.5 percent with incidence as high as 89 percent in some fields. Karnal bunt being seed, soil and air borne is very difficult to manage. The most ideal approach for tackling Karnal bunt is integrated disease management. Since most of the commercially grown wheat varieties are susceptible to Karnal bunt, thus development of resistant varieties is perhaps the most powerful weapon against Karnal bunt. Fungicides posing potential threat to environment and to human and plant health need to e replaced with biological control tools. In order to evaluate efficacy of biological control tools against T.indica, two strains of Trichoderma and two that of Pseudomonas were evaluated In vitro as well as In vivo. During investigations, T. viridae and T. harzianum were used as fungal biocontrol agents and Pseudomonas flouresence (PDBC) and Pseudomonas flouresence (Resident) were the bacterial Bioagents. Studies revealed that T.viride was most effective in checking growth of T. indica in vitro followed by that of T.herzianum, Pseudomonas flouresence ( PDBC) and Pseudomonas flouresence (Resident) were not that effective as fungi were. In vivo studies revealed that T.viridae was more effective in checking growth of Tillitia indica followed by that of T. herzianum. Field application of Pseudomonas flouresence (Resident) gave good check of disease over Pseudomonas flouresence ( PDBC). Out of all the four biological control agents, best result was obtained by using T. viridae.