Bacterial Wilt Control

Symptoms

Plants wilt suddenly during the hottest part of the day and may recover at night in the early stage, but soon wilt permanently and die while the leaves are still green. The lower stem may show brown discolouration inside. A sure test is to cut the lower stem and dip it in clear water, where a milky white thread of bacterial ooze streams out within minutes. The disease appears in patches and spreads in warm wet soil.

Damage

Bacterial wilt caused by Ralstonia solanacearum is one of the most destructive soil borne diseases of tomato, brinjal, chilli and potato in warm humid regions and can cause total loss in badly infested fields. There is no chemical cure once a plant is infected, and the bacterium survives many years in the soil and in roots of weeds, making infected fields unfit for solanaceous crops for a long time. It spreads through soil water, tools, and infected seedlings and transplant water.

Organic & cultural control

Grow resistant or grafted plants, using brinjal or wild solanum rootstock that resists wilt, which is one of the best practical options. Follow long crop rotation of three years or more with non host crops like cereals and maize. Practice deep summer ploughing and soil solarisation to reduce the bacterium. Apply well decomposed farmyard manure, neem cake and bio agents like Pseudomonas fluorescens and Trichoderma to the soil. Ensure good drainage, avoid waterlogging, and remove and destroy wilted plants with the surrounding soil.

Chemical control

There is no spray that cures bacterial wilt, but soil treatment can reduce its spread. Apply bleaching powder to the soil before planting in known sick fields, and drench the root zone with copper oxychloride. A streptocycline plus copper drench is sometimes used around healthy plants to slow spread, but its effect is limited and it must be used as advised. Lime application to raise soil pH also helps. Always follow the product label dose and consult your KVK or agronomist as chemical control alone rarely works.

Always follow the product label, the recommended pre-harvest interval, and your local KVK or agronomist. Pesticide approvals change, so verify before use.

Prevention

Avoid planting solanaceous crops in fields with a known history of wilt and use resistant varieties or grafted seedlings. Raise nurseries in clean disease free soil and use only healthy transplants. Follow long rotation with cereals, maize or other non host crops and avoid waterlogging by planting on raised beds with good drainage. Disinfect tools and do not let water drain from a sick field into a healthy one. Keep fields free of solanaceous weeds and remove wilted plants promptly.