Curvularia leaf spot

The disease is caused by the fungus Curvularia geniculata, a dematiaceous fungus that functions as a potent plant pathogen. It affects a wide range of host plants, acting as a necrotrophic parasite that breaks down plant tissues by releasing toxins and enzymes, leading to visible lesions and tissue death.

Various crops are susceptible to this infection, including corn, sorghum, rice, turfgrasses, and several tropical fruits. In agricultural settings, it is often identified as a major concern for grain yield stability, while in horticultural environments, it causes severe aesthetic and structural damage to foliage and stems.

Symptoms typically begin as small, discolored spots on the leaves, which gradually expand into elliptical, brown lesions often surrounded by a yellow chlorotic halo. As the disease progresses, the central portion of the lesions may turn gray or dark brown. During humid weather, the infected spots develop a velvety, dark-colored mass of spores that can be easily identified under low magnification.

Environmental conditions play a critical role in the epidemiology of Curvularia geniculata. The fungus thrives in high humidity and warm temperatures (ranging from 22°C to 30°C). It spreads via airborne conidia, water splashes, or contaminated equipment. The inoculum can overwinter in soil, debris, or remain latent on dormant plant tissues until conditions favor renewed growth.

Management strategies focus on reducing the initial inoculum and preventing secondary spread. Cultural practices, such as crop rotation, residue management, and improving field drainage, are essential. When environmental conditions pose a high risk of outbreak, the application of preventative fungicides is recommended. Additionally, selection of vigorous, resistant cultivars remains the most effective long-term strategy for minimizing yield losses caused by this fungus.