dc.description.abstract |
Sclerotium rolfsii Sacc. is a soil borne fungal pathogen infects more than 500 species of plants in about 100
families. Management of this pathogen is much difficult because of its wide host range and soil borne in
nature. An experiment was conducted to manage collar rot in potato using plaster of paris (CaSO4.½ H2O)
and microbes. Effect of plaster of paris (@ 2.5g/infected collar region of plant) on two different growth
stages (mycelial stage and sclerotial stage) of S. rolfsii isolated from infected potato plant was determined.
Plaster of paris was applied directly as powder form over the infected area and adverse effect on the
fungus was recorded. The whitish mycelial growth of the fungus from collar region of all the treated plants
was found to disappear. Further formation of sclerotia was stopped. The existing sclerotia became
deformed and dried. The sclerotia and small bits of treated infected plant tissue when transferred to PDA
medium no mycelial growth and sclerotial germination was observed. Whereas, from the untreated infected
plants, growth of thick whitish fan-shaped mycelial growth was observed with huge numbers of
sclerotia. A field experiment was also conducted using four biological agents (Pseudomonas
fluores cens (Flügge) Migula,Trichoderma viride Pers., Azotobacter chroococcum, Glomus
fasciculatum (Thaxt.) Gerd. and Trappe emend. C. Walker and Koske), two organic amendments
(vermicompost and neem cake enriched with neem oil), and one building material (plaster of paris) for
managing the disease at Benuria under Red and Lateritic Agroclimatic Zone of West Bengal during 2014-
15. Randomized Block Design was adopted with three replications. The treatments, vermicompost @ 6kg/
plot i.e. 5.5t/ha, neem cake enriched with neem oil @ 2.2kg/plot i.e. 2t/ha,Pseudomonas fluorescens @
10g/plant, Trichoderma viride @ 10g/plant, Azotobacter chroococcum @10g/plant, Glomus
fasciculatum @10g/plant were applied directly once in the field just before planting. The plaster of paris @
2.5g/plant was dusted twice at the collar region of plant at fifteen days interval starting from 15 days after
planting. Severity of the disease recorded highest in control plots (8.95 and 19.88%) followed byGlomus
fasciculatum (4.92 and 8.11%), neem cake (4.55 and 5.51%) and Trichoderma viride (2.50 and 4.74%)
treated plots while lowest disease severity recorded in plaster of paris (0.70 and 2.65%) followed by
vermicompost (1.05 and 3.80%),Pseudomonas fluorescens (1.41 and 4.30%) and Azotobacter
chroococcum (1.38 and 4.20%) treated plots at 60 and 75 days after planting, respectively. The per cent
disease control (PDC) at 75 days after planting was highest in plaster of paris (90.24%) followed by
vermicompost (85.82%), Azotobacter chroococcum (83.73%) and Pseudomonas fluorescens(83.38%)
treated plots. Trichoderma viride (73.96%) revealed better than Neem cake (62.33%) and Glomus
fasciculatum (52.21). No phytotoxicity has been developed on host plants for the application of plaster of
paris. These effective treatments can be incorporated in Integrated Disease Management Programme for
sustainability. |
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