Ecofriendly management of Rhizoctonia solani causing black scurf of potato
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Date
2018
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CCSHAU
Abstract
In recent years, among different fungal diseases of potato, black scurf disease has emerged as
a serious problem caused by Rhizoctonia solani in most of the potato growing areas of India with 2-70
per cent disease incidence leading to considerable yield losses up to 50 per cent. Due to difficulties in
disease management and lack of stable genetic resistance in potato cultivars against R. solani, different
ecofriendly management aspects including fungicides, bioagents, organic amendments and cultural
practices as well as systemic acquired resistance (SAR) activators in vitro and in vivo conditions were
undertaken for effective management of the disease in present investigation. The in vitro and in vivo
management study involving fungicides, bioagents or organic amendments indicated that among
fungicides, Monceren, MEMC were most effective, whereas, in bioagents Trichoderma harzianum
produced better results followed by T. viride. Among the organic amendments, vermicompost was
found most effective followed by neem cake against black scurf of potato. Besides chemicals and
biological control, cultural practices have also been used to minimize the inoculums level from the soil
and tubers. Black scurf incidence is significantly influenced by irrigation level and depth of planting.
As the irrigation frequency and depth of planting were increased, disease incidence and severity of
potato black scurf was also increased. The delayed date of planting also affects disease incidence and
severity. It was observed that soil moisture content is directly proportional to increased irrigation
frequency and depth of planting. Black scurf disease incidence and severity showed a linear and
negative correlation with soil temperature, whereas, a linear and positive correlation with soil moisture.
Biochemical analysis indicated roles of systemic acquired resistance (SAR) inducing chemicals viz.,
salicylic acid, jasmonic acid, β-aminobutyric acid, γ-aminobutyric acid and hydrogen peroxide against
black scurf of potato caused by R. solani. SAR activators play an important role in biochemical
composition viz., total phenol, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase and
enhanced defense mechanism in potato crop for black scurf. It was also inferred from the study that all
the biochemical constituents initially increased up to peak concentration after that, it decreased. Tubers
dipping of SAR activators were found more effective to control the disease by reducing disease
incidence as compared to foliar spray.
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