Epidemiology, Variability and Management of Tomato Wilt Caused by Fusarium oxysporum f. sp. lycopersici (Sacc.) Snyder and Hansen
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Date
2022
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Abstract
Tomato (Lycopersicon esculentum Mill.) is one of the most
prevailing and important valued vegetable crops belonging to the family
Solanaceae and grown all over the world. Tomato swayed by numerous
biotic and abiotic stresses such as fungi, bacteria, viruses and nematodes
that significantly affect its yield as well as quality. Among the fungal
diseases, Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici
(Sacc.) Snyder and Hansen is regarded as serious pathological threats
and caused considerable yield losses.
A field survey was conducted during Kharif 2019 in four major
tomato growing districts viz., Jaipur, Sikar, Tonk and Udaipur of
Rajasthan. The maximum (22.63%) disease incidence was recorded in
Jaipur and minimum (10.21%) in Udaipur district. The pathogen was
isolated, purified and proved pathogenic by following Koch‟s postulates
and identified as Fusarium oxysporum f. sp. lycopersici. Twelve isolates of
F. oxysporum f. sp. lycopersici were collected and all isolates exhibited
considerably variation in different cultural and morphological
characteristics. The pathogenic behavior of all isolates was also varied from 20.52-78.98 per cent and isolate FOL-02 was found highly
pathogenic with maximum (78.98%) disease incidence.
Maximum mycelial growth and sporulation of F. oxysporum f. sp.
lycopersici was recorded at 25 0C temperature, 90 per cent relative
humidity and 6.5 pH. Potato Dextrose Agar medium was proved better for
higher mycelial growth and sporulation. The accumulation of total phenol
and protein contents were gradually higher after inoculation of pathogen.
The higher accumulation of phenol and protein contents of plants were
recorded in moderate resistant (Heemsohna and Abhilash) and minimum
in susceptible (S-22 and Azad T-6) varieties.
Among weather factors, the per cent disease incidence was
positively correlated with maximum temperature whereas with other
factors i.e. minimum temperature, morning and evening relative humidity
and rainfall it was negatively correlated during both years (Kharif, 2019
and 2020). Out of 16 screened varieties, none was found free. However,
seven varieties were moderately resistant, seven were moderately
susceptible while two varieties were susceptible.
On the basis of in vitro experiments the efficacy of neem leaf
extracts @ 10%, Trichoderma harzianum and carbendazim @ 300 ppm
were found most promising in inhibition of mycelial growth and reducing
the disease incidence under pot conditions. Under field conditions, soil
application of Trichoderma harzianum @ 2.5 kg/100 kg FYM/ha + root dip
with carbendazim @ 0.1% for 30 min.+ drenching with carbendazim @
0.1% at 35 DAT was proved effective in reducing disease incidence and
in increasing fruit yield. However, the Incremental Cost Benefit Ratio was
found best (1:37.88) with soil application of Trichoderma harzianum @ 2.5
kg/100 kg FYM/ha + root dip with carbendazim @ 0.1% for 30 min. due to
lower cost of inputs.