Which characteristic of corn smut makes it particularly damaging to its host plants?

The production of galls that disrupt plant tissues is the characteristic of corn smut that makes it particularly damaging to its host plants. Corn smut (Ustilago maydis) is a fungal pathogen that infects corn, leading to the development of galls—tumor-like growths—on various parts of the plant, including the ears, stalks, and leaves. These galls not only affect the aesthetic and commercial value of the corn but also impair the plant’s ability to function normally. As the gall tissue replaces healthy plant tissue, it can significantly hinder nutrient transport and water uptake, ultimately leading to reduced yield and quality of the corn.

Additionally, galls can serve as a reservoir for the pathogen, facilitating further spread within and between plants. This disruption of plant tissues effectively compromises the vitality of the host, making this characteristic the primary reason for the pathogenicity and economic impact of corn smut.