Controlling Tundu Disease in Wheat

Tundu disease, commonly known as 'Sehwan' in many parts of India, is a destructive disease of wheat caused by a complex interaction between a nematode (Anguina tritici) and a bacterium (Clavibacter tritici). This disease can significantly reduce yield and grain quality. The nematode galls carry the bacteria, and both are introduced into the field through infected seeds. Understanding how to identify and manage this disease is crucial for protecting your wheat harvest.

Recognizing Tundu Disease Symptoms

Identifying Tundu disease early is important for timely management. The symptoms typically appear as the wheat plant grows, becoming more prominent during the heading stage.

Early Symptoms: Young seedlings may show twisted, crinkled, or distorted leaves. Plants might appear stunted compared to healthy ones.
Characteristic Yellow Slime: The most distinctive symptom is the appearance of a bright yellow, sticky, bacterial ooze on the glumes (outer covering) of the developing wheat ears. This ooze can dry into a shiny, yellow crust.
Distorted Ears: Infected ears often become twisted, malformed, and remain upright instead of nodding naturally. They may also be darker green than healthy ears.
Shrivelled Grains: Inside the infected ears, the grains are often replaced by dark brown or black, hard nematode galls, which are smaller and lighter than healthy wheat grains. These galls are the primary source of infection for the next season.

Preventing Tundu Through Clean Seed

The primary way Tundu disease spreads is through infected seeds containing nematode galls. Therefore, using clean, disease-free seed is the most critical step in prevention.

Certified Seeds: Always purchase certified, disease-free wheat seeds from reliable sources. These seeds are typically screened for diseases.
Salt Water Treatment: If using farm-saved seeds, a simple salt water treatment can help remove nematode galls. Dissolve 10 kg of common salt in 100 litres of water. Soak the wheat seeds in this solution for about 5-10 minutes. The lighter nematode galls will float to the surface and can be skimmed off and destroyed. Rinse the healthy seeds thoroughly with fresh water immediately after treatment to remove salt, then dry them in the shade before sowing.

Seed Treatment for Effective Control

Even after physical cleaning, chemical seed treatment provides an extra layer of protection against Tundu disease and other seed-borne pathogens. This is especially important if Tundu has been a problem in your area.

MethodDescriptionBenefitSalt Water TreatmentDissolve 10 kg common salt in 100 litres of water. Soak wheat seeds for 5-10 minutes.Nematode galls (containing bacteria) float and can be skimmed off, reducing primary inoculum.Chemical Seed TreatmentTreat seeds with a recommended nematicide and bactericide combination before sowing.Protects against early infection from any remaining galls or soil-borne pathogens, ensuring healthy seedling establishment. Consult local agricultural extension for specific product recommendations and dosages.

Cultural Practices and Field Management

Good agricultural practices play a vital role in reducing the incidence and spread of Tundu disease in your fields.

Crop Rotation: Avoid planting wheat in the same field year after year. Rotate wheat with non-host crops like pulses (e.g., chickpea, lentil), mustard, or fodder crops for at least 2-3 years. This helps break the disease cycle by starving the nematode and bacterium in the soil.
Field Sanitation: Remove and destroy any infected wheat plants or stubble observed in the field. Do not leave infected plant debris, as it can harbor the disease.
Deep Ploughing: After harvest, deep ploughing can help expose any remaining galls in the soil to sunlight and desiccation, reducing their viability.
Weed Control: Some weeds can act as alternative hosts for the nematode or bacteria, so keeping fields free of weeds is beneficial.

Choosing Resistant Varieties

While completely resistant varieties to Tundu disease are rare, some wheat varieties show a higher level of tolerance or less susceptibility. Consult your local agricultural university or extension worker for recommendations on wheat varieties known to perform better against Tundu disease in your region.

Controlling Tundu disease in wheat requires an integrated approach. By combining the use of clean, treated seeds with effective cultural practices like crop rotation and field sanitation, farmers can significantly reduce the impact of this disease and ensure a healthier, more productive wheat crop.