Chrysanthemum flower (Chrysanthemum morifolium Ramat.) is popularly designated as "Queen of the east", or autumn queen (as its bloom in November-December). F. oxysporum f. sp. chrysanthemi causing vascular wilt of chrysanthemum is one of the most devastating pathogens infecting this flower crop. This particular disease gains more significance in terms of economic loss as it can attack the crop at all the growth stages ranging from nursery to flowering. Considering the seriousness of the disease and economic importance of the crop study of this pathogen becomes more essential in all aspects, i.e., cultural, biochemical and molecular aspects. In this experiment an attempt was made to record reaction of F. oxysporum f. sp. chrysanthemi in terms of cultural characteristics on seven different culture media. Data recorded after 10 days of inoculation, exhibited that Corn Extract Agar was the best media with 89.33 mm radial growth, while as, Czapek's Dox Agar supported least radial growth of 58.33 mm. The test fungus sporulated on all the culture media under test, but, RSA and CEA supported maximum sporulation.
In-vitro effectiveness of various antagonistic fungi namely Aspergillus niger, A. flavus, Trichoderma koningii, T. atroviride, and T. harzianum were evaluated against Rhizoctonia solani by dual culture technique on potato dextrose agar. According to the observation recorded after 5 days, all the treatments were found to be superior over control (R. solani), but among all treatments A. niger was found to the most effective antagonist, with highest radial growth inhibition of the pathogen (77.01 percent), followed by A. flavus, T. harzianum and T. koningii i.e., 66.23, 64.42 and 62.20 percent. While as, T. atroviride was found to be the least effective one with minimum growth inhibition i.e., 42.21 percent. Whereas, at the same time control (R. solani) showed 100 percent radial growth and covered the whole Petri Plate within 5 days. All the bio-control agents were significantly effective to inhibit the sclerotia formation and development, except T. atroviride in which formation of sclerotia was recorded, while in all other treatments complete inhibition of sclerotia formation was recorded after 10 days of incubation.
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