Which disease might cause lodging in grain sorghum fields?

Charcoal rot is a fungal disease that affects grain sorghum and is known to lead to lodging, which is the bending or falling over of the plant. This occurs because the disease can weaken the plant's stem structure. When charcoal rot infects the plant, it often reduces its vigor and structural integrity, especially under stress conditions such as drought. As the disease progresses, the stems become brittle and may not be able to support the weight of the grain heads, resulting in lodging.

In contrast, while bacterial streak and powdery mildew can affect the overall health of grain sorghum, they do not typically lead to significant lodging. Bacterial streak primarily causes leaf symptoms that can reduce photosynthetic capacity but does not directly weaken stems to the same extent as charcoal rot. Powdery mildew affects the surface of the leaves, diminishing their function, yet it does not generally compromise stem strength or support, thus is less associated with lodging. Thrips damage primarily concerns the foliage and may lead to reduced yield but is not directly linked to causing plants to lodge.

By understanding the effects of these diseases on plant structure and integrity, it's clear that charcoal rot has a distinctive and impactful role in causing lodging in grain sorghum fields.