What is the shape of the stem affected by anthracnose in alfalfa?

The shape of the stem affected by anthracnose in alfalfa is best described as a shepherd's crook. This distinctive curvature is a characteristic symptom of anthracnose, which is a fungal disease that impacts the plant's vascular system.

When alfalfa plants are infected, the disease often causes the stem to bend excessively, resembling the curved shape of a shepherd's crook. This bending occurs as a result of the disease disrupting normal growth patterns, leading to weakened and distorted stems. In contrast, other shapes like a straight cylinder, curved hook, or twisted spiral do not accurately reflect the specific type of deformation caused by the disease. Understanding this symptom helps growers identify and manage the disease effectively, distinguishing it from other issues that may affect alfalfa crops.