Management of bacterial wilt in tomato
Though several diseases are major hurdles in its cultivation, bacterial wilt is most devastating causing severe tomato yield losses up to 90 percent. The disease is also known as southern bacterial blight or solanaceous wilt.
Common symtoms
Rapid and complete wilting of normal grownup plants is a characteristic symptom of bacterial wilt.
During warm and wet climatic conditions the most common symptom of sudden drooping of leaves, without yellowing, often accompanied by rotting of the stem are seen.
The disease is caused by a bacterium Ralstonia solanacearum, that infects more than 200 plant species. The pathogen is soil borne and survives for 2 years in absence of any host.
How it spreads
It is found in soil up to 45cms depth and spreads through irrigation water, soil movement, implements and infected plant material.
It is more severe in sandy loam soil and is favoured by high temperature (30-35{+o}C) and high soil moisture.
The bacterium enters through wounds created during transplanting, cultivation, by insects or nematodes invasion.
Wilt occurs within 2-5 days after infection depending upon host susceptibility, temperature and virulence of the pathogen.
Management
— The disease can be kept under check if crop rotations are followed with crops such as maize, ragi and okra, since they can reduce the pathogen population significantly.
— Several biological control agents such as Pseudomonas fluorescens, Bacillus licheniformis, B. cereus, B. subtilis and mycorrihiza are effective in delaying and reducing the wilt development.
—Tomato seedlings can be treated with root dipped in Pseudomonas fluorescens before planting. .
—Application of bleaching powder (15kg/ha) has also been found effective against this disease.
—Bacterinol – 100 can be used as dry seed dresser for nursery spray and filed application.
— Varieties such as Arka Abha, Sonali, DPT-38 and Arka Alok which are resistant to bacterial wilt can be used for cultivation.
Mallikarjun Y Kenganal
& Byadgi, A.S.
Department of Plant Pathology
University of Agricultural Sciences, Dharwad
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