Sclerosporosis

Sclerosporosis is a severe plant disease caused by oomycetes within the order Sclerosporales. These pathogens are classified as downy mildews and act as obligate parasites, primarily infecting cereal crops during their early growth stages, leading to significant yield losses globally.

The disease frequently attacks crops such as maize, millet, sorghum, and various wild grasses. The pathogen infects seedlings directly through the roots, allowing the mycelium to spread systemically throughout the plant's vascular system, which disrupts nutrient transport and causes stunted growth.

Visible symptoms often include chlorotic stripes on the leaves, mosaic patterns, and extreme deformation of the plants. In severe cases, the reproductive organs, such as tassels or ears in corn, are replaced by abnormal, leaf-like structures, effectively rendering the plant completely sterile and preventing seed production.

Development and spread are favored by high soil moisture levels and moderate temperatures, particularly during the germination phase. The pathogen produces oospores that can survive in the soil or on crop residues for several years, making the infection cycle difficult to break without active management.

Effective management strategies include the planting of resistant or tolerant cultivars and strict adherence to crop rotation cycles. Seed treatment with systemic fungicides is crucial to protect emerging seedlings from soil-borne inoculum, while rigorous weed control helps eliminate alternative hosts that sustain the pathogen population.