Karnal bunt

Karnal bunt, also known as partial bunt, is a fungal disease that affects wheat (Triticum spp.) and related cereal crops. It is caused by the fungus Tilletia indica. Karnal bunt is a significant concern for wheat growers because it can lead to reduced crop quality and economic losses. Here is a description of Karnal bunt:

Symptoms: Karnal bunt primarily affects the wheat kernels, and the symptoms become noticeable during and after harvest. The key symptoms of Karnal bunt include:

1. Smell: Infected wheat kernels emit a distinctive fishy or foul odor, which is often the first sign of infection.

2. External Appearance: Infected kernels may appear normal from the outside, making it difficult to detect the disease visually. However, some infected kernels may exhibit small, dark brown to black specks or pustules on the surface.

3. Internal Damage: The most significant damage occurs inside the kernel. When infected kernels are broken or cut open, they reveal a powdery mass of spores. These spores are often dark brown to black and have a characteristic fishy odor.

Disease Cycle: Karnal bunt has a unique disease cycle:

1. Infection: The fungal spores (teliospores) of Tilletia indica can survive in the soil for extended periods. Infection occurs when these spores come into contact with developing wheat spikes during the flowering stage.

2. Systemic Growth: The fungus penetrates the developing kernels, and its mycelium grows inside the kernels without causing external symptoms.

3. Spore Production: Infected kernels serve as a source of fungal spores for the next season. When infected kernels are planted as seed, they can transmit the disease to the new crop.

Environmental Conditions: Karnal bunt is favored by specific environmental conditions, including cool temperatures (between 15-24°C or 59-75°F) and high humidity during the flowering stage of wheat. These conditions promote fungal infection and spore production.