• Causative agent: False smut is caused by the fungus Ustilaginoidea virens (also known as Villosiclava virens).
• Affected crop: Primarily rice (paddy).
• Symptoms: Individual rice grains are transformed into velvety, ball-shaped spore masses called smut balls. These start orange-yellow and mature into greenish-black. The smut balls enclose floral parts and release powdery spores when ruptured.
• Disease occurrence conditions: High relative humidity (>90%), temperatures 25-35°C, rainy and damp weather with soils rich in nitrogen favor disease development.
• Impact: Causes chalkiness in grains, reduces 1000-grain weight and seed germination by up to 35%. Yield losses can range from 7%-75% in India, 3%-70% generally depending on conditions.
• Infection stage: The fungus infects rice during the flowering stage, targeting floral organs including stamens, which are critical for smut ball formation.
• Disease cycle: Spores germinate on spikelets and infect inner floral parts; chlamydospores and sclerotia help fungus overwinter in soil and seeds.
• Mycotoxins: The fungus produces ustiloxins and ustilaginoidins, which are carcinogenic and harmful to human and animal health.
• Management: Use of resistant varieties, seed treatment, moderate nitrogen use, field sanitation by removing infected seeds and debris, alternate wetting and drying rather than continuous flooding helps reduce humidity and disease development.

• Destroying infected straw and stubble after harvest to reduce the primary inoculum for the next crop is essential.
• Use of certified disease-free or sclerotia-free seeds helps reduce initial infection.
• Cleaning bunds and controlling weed grasses around rice fields limit pathogen reservoirs.
• Furrow irrigation has been found effective in reducing disease severity.
• Maintaining moderate nitrogen fertility rates and practicing crop rotation.
• Spraying fungicides such as carbendazim, copper-based fungicides, propiconazole, chlorothalonil, mancozeb, and captan at the tillering and flowering stages.
• Planting resistant or tolerant rice hybrids identified through screening.
• Biocontrol agents such as Bacillus subtilis and plant extracts like garlic and turmeric have shown inhibitory effects on the pathogen.

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