BIO- INTENSIVE MANAGEMENT OF DAMPING – OFF OF TOMATO (Solanum lycopersicum L.)
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Date
2019-10
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UHF,NAUNI
Abstract
ABSTRACT
In the present investigations on damping-off of tomato, characteristic symptoms of the disease
first appeared in two phases i.e. pre- emergence and post- emergence. In the first phase, infected seeds
failed to germinate while in second phase, small water soaked lesions on the stem appeared at soil line
leading to toppling over of the seedling on ground level. Four fungal pathogens namely P. ultimum, F.
oxysporum, R. solani and S. rolfsii were isolated from infected seedlings. Identification of the isolated
pathogens was done on the basis of various morphological and cultural characteristics. Morphological
studies revealed that pathogens were fast growing on artificial medium with initially white cottony and
profusely growing mycelium attaining a colony diameter of 90 mm within 3-6 days days. In case of P.
ultimum, hyphae were hyaline and coenocytic, produced sporangia and oospore. In F. oxysporum, the
mycelium was hyaline and had branches and produced macroconidia, microconidia and chlamydospores.
In R. solani, the mycelium was septate, colour of the hyphae was brown. The branching occurred almost at
right angles to the hyphal cell and produced sclerotia. In S. rolfsii, the hyphae was hyaline, thin walled,
sparsely septate when young. Sclerotia were dark brown but variation from lighter brown to darker colour
was found. Pathogenicity test revealed that disease incidence was more 94.44 per cent in pre-emergence
phase while it was 50.00 per cent in post-emergence phase. During in vitro thermal sensitivity of inocula of
fungal pathogens of damping-off of tomato maximum mycelial growth inhibition was recorded in P.
ultimum (5.56%) followed by F. oxysporum (4.95%) and R. solani (3.73%). Soil solarization increased the
mean soil temperature by 3.49 ºC at 5 cm depth as compared to nonsolarized control at the same depth.
Soil solarization for 30 days resulted in killing of the pathogens F. oxysporum and R. solani while all the
pathogen were not viable after 40 days of soil solarization. Among different antagonists evaluated, T.
harzianum caused maximum mycelial inhibition under in vitro conditions and was also found effective
under the pot conditions. There was significant reduction in the disease incidence with Lantana camara
(37.50%) followed by Vitex nigundu (39.16%) in the pot conditions. Among SAR chemicals potassium
chloride and potassium dihydrogen phosphate when applied at 300 and 200 mM concentration were found
effective and resulted in (16.66%) and (20.24%) disease incidence, respectively. The minimum disease
incidence of damping-off was recorded in the field conditions with the combination of all the treatments
(soil solarization + soil application of T. harzianum + soil application of Lantana camara + seedling
treatment of potassium chloride) resulted in 13.11 per cent disease incidence and 74.88 per cent disease
control.
Signature of the Student Signature of Major Advisor
Name: Swadha Bhardwaj N
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